Technical Program

Thursday 5 September 2019

 

09:00-10:30 - Plenary Sessions - Amphi Lavoisier

Chairperson: Peter Siegel

09:00 Th-Pl-7

Quantum materials: Insights from THz and infrared nano-optics

Dmitry BASOV, Columbia University, USA

09:45 Th-Pl-8

THz Instrumentation And Analysis Techniques For Biomedical Research

Emma MACPHERSON, Warwick University, UK

10:30-11:00 - Coffee Break

11:00-12:30 Parallel sessions Th-AM

11:00-12:30 - Th-AM-1 - Imaging 1 - Amphi Lavoisier

Chairperson: Kaori Fukunaga

11:00 Th-AM-1-1
Stationary Sample Anisotropic THz Spectroscopy Using Discretely Tunable THz Sources

Timothy LaFave
1; Deepu George2; Ian McNee3; Vladimir Kozlov3; Peter Schunemann4; Andreas Markelz1
1University at Buffalo, SUNY, United States; 2University at Buffalo,United States; 3Microtech Instruments, United States; 4BAE Systems, United States

We demonstrate anisotropic THz spectroscopy of sucrose using newly developed compact discretely tunable THz sources for turn-key spectroscopic systems

11:30 Th-AM-1-2
Terahertz Homodyne Imaging For Inspection Of Low Absorbing Objects
Domas Jokubauskis; Linas Minkevičius; Dalius Seliuta; Irmantas Kasalynas; Gintaras Valusis
Center for Physical Sciences and Technology, Lithuania

Terahertz (THz) imaging of low absorbing objects is evaluated both in direct and homodyne set-ups at 0.3 THz and 0.6 THz at room temperature. Dynamic range increase by more than two order of magnitude in homodyne detection scheme is shown. Phase shift in homodyne approach is realized with no moving optical elements by using paper sheets. It is shown that the homodyne detection scheme is a very promising for identification of objects exhibiting low absorption of THz radiation, for instance, paper tissue, nitrile and low-density polyethylene concealed in textile.

11:45 Th-AM-1-3
Optically Initiated Spatial Modulation Of THz Radiation At Far-field Distances Using A Compressed Sensing Protocol

Sven Augustin1; Peter Jung2; Sven Frohmann3; Heinz-Wilhelm Huebers1
1HU Berlin, Germany; 2TU Berlin, Germany; 3DLR Berlin, Germany

We present the first results of an optical modulation approach for 0.35 terahertz radiation imaging applied at stand-off distances using a Compressed Sensing protocol. Despite the common believe, optical modulation approaches are applicable for imaging at stand-off distances and we discuss the achieved edge fidelity, the overall image quality as well as limiting factors for our specific approach.

12:00 Th-AM-1-4
Terahertz Imaging By THz→IR Conversion

Arthur Salmon; Patrick Bouchon; Sylvain Rommeluère; Riad Haidar
ONERA, France

A low-cost THz→IR converter based on a printed metasurface is fabricated. The converter is a thin membrane which absorbs the terahertz radiation at a single frequency using a grating of antennas, and converts it into thermal IR radiation. Here, we demonstrate THz imaging at 96 GHz using an IR camera equipped with the converter. The membrane can be upgraded to convert simultaneously multiple frequencies thus giving a possible path for terahertz multispectral imaging using an IR camera

12:15 Th-AM-1-5
Carbon-based Terahertz Zone Plates

Rusne Ivaskeviciute; Linas Minkevicius; Andzej Urbanovic; Lukas Laurinavicius; Rasa Pauliukaite; Gintaras Valusis
Center for Physical Sciences and Technology, Lithuania

It is demonstrated that graphite and graphite composites can be used as a core material to fabricate carbon-based terahertz zone plates. Experimental results confirm that it can be an optimal route in designing on-chip spectrometers for THz frequency range.

11:00-12:30 - Th-AM-2 - Photomixers - Petit Amphi

Chairperson: Guillermo Carpintero

11:00 Th-AM-2-1
Continuous-Wave Electro-Optic Terahertz Dual-Comb Operating From 0.096 To 0.496 THz Using ErAs:In(Al)GaAs Photoconductors
Anuar Fernandez Olvera1; Andres Betancur2; Cristina de Dios2; Sascha Preu1; Pablo Acedo2
1TU Darmstadt, Germany; 2UC3M, Spain

An absolute-frequency terahertz (THz) dual-comb system was implemented using only standard telecom components, such as continuous-wave (CW) single mode lasers, optical modulators, and erbium-doped fiber amplifiers (EDFAs) for driving a pair of ErAs:In(Al)GaAs photoconductors. The dual-comb center frequency was tuned between 0.09596 and 0.49596 THz while the mode spacing was kept at 0.5 GHz, although any other lower frequency was also possible.

11:30 Th-AM-2-2
A Broadband Millimeter-wave Photomixing Emitter Array Employing UTC-PD And Planar Antenna

Muhsin Ali1; Andrzej Jankowski2; Robinson C. Guzmán1; Frédéric van Dijk2; Luis E. García-Muñoz1; Guillermo Carpintero1
1Universidad Carlos III de Madrid, Spain; 2III-V Lab, Campus de Polytechnique, France

In this paper we present a novel scalable photonics-based emitter array, integrating high speed uni-travelling carrier photodiodes and high gain planar antennas in 50 — 120 GHz frequency range. The proposed emitter provides a record 3-dB bandwidth of 45 GHz, covering three waveguide bands (V, E and F). In addition, a combined radiated power of 230 µW is achieved. The presented approach enables realization of photonics-based millimeter and terahertz wave beamsteering.

11:45 Th-AM-2-3
LT-GaAs-based Photomixers With >2mW Peak Output Power Up To 320 GHz
Fuanki Bavedila; Etienne Okada; Jean-François Lampin; Guillaume Ducournau; Emilien Peytavit
IEMN CNRS/Université de Lille, France

It is shown in this communication that a LT-GaAs photomixer based on an optically resonant cavity is able to generate peak output powers above 2 mW up to 320 GHz when it is driven by optical pulses of 5 ns width at a repetition rate of 10 MHz.

12:00 Th-AM-2-4
Wideband Radiation Pattern Simulation And Measurement Of A Photodiode-Based Continuous-Wave THz Emitter
Kevin Kolpatzeck1; Xuan Liu1; Simon Nellen2; Benedikt Friederich1; Dilyan Damyanov1; Lars Haering1; Thorsten Schultze1; Bjoern Globisch2; Jan C. Balzer1; Andreas Czylwik1
1Universität Duisburg-Essen, Germany; 2Fraunhofer Heinrich Hertz Institute, Germany

In this paper, the radiation characteristics of a PIN photodiode-based terahertz emitter are simulated using the finite-difference time-domain (FDTD) method. The simulation results are validated by measurements from 100 to 400 GHz. Azimuth and elevation radiation patterns are compared and investigated in terms of beamwidth and sidelobes.

12:15 Th-AM-2-5
Beam Profile Investigation Of An Optoelectronic Continuous-Wave Terahertz Emitter
Jess Smith1; Simon Nellen2; Sebastian Lauck2; Björn Globisch2; Mira Naftaly1
1National Physical Laboratory, United Kingdom; 2Heinrich Hertz Institute, Germany

The beam profile of an optoelectronic continuous-wave terahertz emitter is investigated in the frequency range up to 200 GHz. The radiation pattern is measured by a calibrated pyroelectric power detector. As these frequencies are promising for terahertz communications, knowledge and predictability of radiation pattern are required for link budged estimation. This abstract could contribute to the potential planned Special Session on THz Communication for beyond 5G.

11:00-12:30 - Th-AM-3 - Instrum. Astro 1 - Room 151

Chairperson: Alain Maestrini

11:00 Th-AM-3-1
A Space Mission To Probe The Trail Of Water

Paul Goldsmith; Youngmin Seo
Jet Propulsion Laboratory, California Institute of Technology, United States

We present a concept for a submillimeter spectroscopic mission to probe the trail of water from the interstellar medium to habitable planets. Water is an essential ingredient for life as we know it, and understanding how water is transported to planets in forming planetary systems is a fundamental question that we need to answer in order to understand how ocean worlds evolve throughout the universe.

11:30 Th-AM-3-2
First Light Results From A Novel Cryogenic Fabry-Perot Interferometer
David Naylor1; Ian Veenendaal1; Trevor Fulton1; Brad Gom1; Adam Christiansen1; WIllem Jellema2; Carolien Feenstra2; Martin Eggens3; Peter Ade4
1University of Lethbridge, Canada; 2Kapteyn Astronomical Institute, University of Groningen, Netherlands; 3SRON, Netherlands Institute for Space Research, Netherlands; 4Cardiff University, United Kingdom

The sensitivity of state-of-the-art superconducting far-infrared detectors is such that astronomical observations at these wavelengths are limited by photon noise from the astronomical source unless a method of restricting the spectral bandpass is employed. One such method is to use a high resolution Fabry-Perot interferometer (FPI) in conjunction with a lower resolution, post-dispersing system, such as a grating spectrometer. The resonant wavelength of an FPI is typically tuned by changing the spacing or medium between the parallel reflecting plates of the etalon. We previously reported on a novel design in which the wavelength is tuned by scanning the angle of incidence, which simplifies the cryo-mechanical design, actuation and metrology. Here we present first light results from the realized instrument.

11:45 Th-AM-3-3
Quasi-Optical System For The ASTE Telescope With 1:3 Bandwidth At Sub-mm Wave
Shahab Oddin Dabironezare1; Giorgio Carluccio1; Alejandro Pascual Laguna1; Sebastian Hähnle2; Jochem Baselmans2; Nuria Llombart1
1Technical University of Delft, Netherlands; 2Netherlands Institute for Space Research, SRON, Netherlands

DESHIMA is a spectrometer for astronomical applications targeting sources at sub-mm wavelengths from 240GHz to 720GHz that will operate in the ASTE telescope in Atacama Desert, Chile. In this work, a quasi-optical system based on a hyper-hemispherical leaky lens antenna and a series of Dragonian reflectors is presented as the coupling chain for the EM radiation captured by the telescope into the detector. The design procedure is based on a field matching technique in reception. The achieved average illumination efficiency over the band is approximately 70%. The directivity patterns in the sky are also estimated. The side lobe, and cross-polarization levels, over the whole frequency band, are below -16dB, and -18dB, respectively. The measurement of the system is on-going, and will be presented at the conference.

12:00 Th-AM-3-4
Recent Progress In The Development Of French THz Schottky Diodes For Astrophysics, Planetology And Atmospheric Study

Lina Gatilova1; Alain Maestrini1; Jeanne Treuttel1; Thibaut Vacelet1; Yong Jin2; Antonella Cavanna2; Laurent Couraud2; Alexandre Féret1; Gregory Gay1; Sylvain Caroopen1; Jérôme Valentin1; Sabrina Mignoni1; Jean-Michel Krieg1; Christophe Goldstein3
1LERMA - Observatoire de Paris, France; 2C2N-CNRS, France; 3CNES, France

During the last 10 years the LERMA-Observatoire de Paris in close collaboration with C2N has made a great progress in the development of the French technology of THz electronic components based on Schottky diodes. By bringing together the unique knowledge and skills of both laboratories, we have developed the submillimeter devices at 300GHz, 600GHz and 1.2 THz, with state-of-the-art performances. These devices are selected today for the SWI instrument of the JUICE satellite, ESA's first class L mission. The progress made over the last years and our future work on the device miniaturization and increasing working frequency will be discussed in this presentation.

12:15 Th-AM-3-5
Far- And Mid-IR Heterodyne Detectors Based On MgB2

Boris Karasik1; Daniel Cunnane1; Jonathan Kawamura1; Darren Hayton1; Narendra Acharya2; Wenura Withanage2; Xiaoxing Xi2
1Jet Propulsion Laboratory / California Institute of Technology, United States; 2Temple University, United States

This will be an overview of our work on the development of hot-electron bolometers (HEB) and Josephson junctions (JJ) using thin films of high-TC MgB2 superconductor for applications as heterodyne detectors in the far-IR and mid-IR spectral ranges. Besides the high operating temperature (15-20 K), the MgB2 material provides a large intermediate frequency (IF) bandwidth ~ 6-7 GHz for HEB mixers and record high operating frequency ~ 2 THz for JJ mixers.

11:00-12:30 - Th-AM-4 - Cameras - Room 101

Chairperson: Ken Wood

11:00 Th-AM-4-1
Multi-view Terahertz Imagers With Flexible Carbon Nanotube Film Arrays

Kou Li1; Ryoichi Yuasa1; Ryogo Utaki1; Meiling Sun1; Yu Tokumoto1; Daichi Suzuki2; Yukio Kawano1
1Tokyo Institute of Technology, Japan; 2RIKEN, Japan

To realize terahertz (THz) imaging applications regardless the shape and size of inspection objects, we previously developed flexible THz imaging device based on macroscopically bendable carbon nanotube (CNT) films which show high absorption ratio in the broadband frequency region. Here we report on novel type multi-view THz imaging methods which enabled us to visualize both the outer / inner surface condition of cylindrical / columnar industrial products including electrical lines and gas pipes by a usage of the newly designed CNT film flexible THz imaging devices. Furthermore, device coupling with self-driving robots was performed toward the realization of IoT THz inspection device modules.

11:30 Th-AM-4-2
Resolution Limits In Lens-integrated CMOS THz Cameras Employing Super-Resolution Imaging

Robin Zatta1; Ritesh Jain2; Janusz Grzyb1; Ullrich Pfeiffer1
1Institute for high frequency & communication technology, Germany; 2Bergische Universität Wuppertal, Germany

In this paper, we discuss the design choices of CMOS THz cameras for achieving maximum angular resolution and high sensitivity over a large bandwidth. In an active THz imaging set-up, the spatial resolution becomes a function of the object magnification, determined by the focal length of the collimating optic and the camera's angular resolution. The THz camera investigated experimentally here, under-samples its field-of-view for incident frequencies above 0.578 THz due to its 80um pixel pitch coupled with narrow pixel beams. With the help of super-resolution imaging, the camera reaches a measured angular resolution of 1.92 degrees at 0.652 THz. At 0.822 THz, where the camera exhibits optimum NEP, the presented super-resolution model predicts an estimated angular resolution of 1.65 degrees.

11:45 Th-AM-4-3
A CMOS Multispectral Imager With Terahertz And Visible Pixels

Matteo Perenzoni; Moustafa Khatib
FBK, Italy

In this paper a CMOS image sensor featuring pixels with both THz and visible (VIS) sensing capabilities is presented. The THz-VIS imager includes, in the same focal plane array, 10x10 THz pixels with embedded analog-to-digital conversion and 50x50 VIS active pixels for simultaneous imaging. First images are captured in the THz and in the VIS range.

12:00 Th-AM-4-4
Far-Infrared Room-Temperature Focal Plane Modules For Polar Radiant Energy In The Far InfraRed Experiment

Giacomo Mariani; Matthew Kenyon; Byeong Eom; Brian Drouin; Mary White
NASA Jet Propulsion Laboratory, United States

This work presents focal plane modules for Polar Radiant Energy in the Far InfraRed Experiment, a passive remote-sensing instrument aimed to determine errors in the estimated outgoing longwave radiation in the Earth's polar regions to reduce uncertainties in surface emissivity, mass balance, and ice flux. The focal plane arrays are micromachined at JPL and integrated into sub-assembly modules to be mounted on the optical telescope of the instrument.

12:15 Th-AM-4-5
RIGI Camera For Real Time Ultrasensitive Terahertz Imaging
Gunther Steinfeld; Corinne Brodeur; Mostafa Shalaby; Gustavo Santiso
Swiss Terahertz LLC, Switzerland

we introduce the RIGI camera platform as a real time high sensitivity terahertz imager with a pixel size of 15 µm and NEP of 1.5 pW/ Hz0.5

11:00-12:30 - Th-AM-5 - Metamaterials 5 - Room 162

Chairperson: Jun Wang

11:00 Th-AM-5-1
Thermally Switchable Terahertz Metasurface Devices
Yan Zhang; Xinke Wang
Capital Normal University, China

Two kinds of active metasurface modulators for dynamically controlling the wavefront of terahertz radiation are designed and fabricated. The modulators are made of vanadium dioxide film. When the environment temperature is higher than the phase transition temperature of vanadium dioxide, the modulators can transfer the x-polarization terahertz wave into y-polarization with desired phase and amplitude modulation, thus the wavefront of the terahertz wave can be modulated. Experiment results demonstrate the validity of the proposed approach.

11:30 Th-AM-5-2
Sensitive terahertz phase modulation via a co-planar HEMT-switched LC-dipole resonant metasuraface under low 2DEG carrier concentrations

Feng Lan1; Pinaki Mazumder2; Luyang Wang1; Hongxin Zeng1; Ziqiang Yang1; Tianyang Song1; Jing Yin1; Ziqi Zhang1; Zongjun Shi1
1University of Electronic Science and Technology of China, China; 2University of Michigan, United States

A terahertz digital phase modulator based on an ultrafast electrically controlled HEMT-embedded metasurface is theoretically and experimentally demonstrated here.Different from traditional delay-line phase shifter,the proposed phase modulator combined the active HEMT 2DEGs with the resonant structure,demonstrating higher reflective efficiency and 2Ãfââ?s¬full coverage phase shift under low electron densities around 1015/m2.The preliminary measurement results show a Ãfââ?s¬ phase difference occurs at 0.358 THz with a -8.5 dB attenuation on average,which is in good accordance with the simulation.

11:45 Th-AM-5-3
Tunable Terahertz Planar Lens Based On The Dynamic Meta-surface

Ting Chen1; Wei Kou1; Yaxin Zhang1; Qiwu Shi2; Ziqiang Yang1; Shixiong Liang3
1Terahertz Science Cooperative Innovation Center, China; 2SiChuan University, China; 3National Key Laboratory of Application Specific Integrated Circuit, Hebei Semiconductor Research Ins, China

We present a terahertz tunable planar lens based on the dynamic meta-surface. The simulation results show that the focus switch of a flat lens can be realized by the phase transition characteristics of VO2, which provide a potential application in the system of THz imaging.

12:00 Th-AM-5-4
Broadband Terahertz Modulator Based On The Graded Gaps

Xiaoqing Guo1; Yaxin Zhang1; Shixiong Liang2
1University of Electronic Science and Technology of China, China; 2Hebei Semiconductor Research Institute, China

In conclusion, combining graded gaps microstructure with the HEMT diode yielded a THz broadband amplitude modulator that is modulated from 0.64 to 0.74 THz to a depth greater than 80%.

12:15 Th-AM-5-5
Extremely Low Threshold Optical Switching And Modulation Of Ion-irradiated High-Tc Superconductor Metamaterial

Jerome Lesueur1; Yogesh Srivastava2; François Couëdo3; Prakash Pitchappa2; Cheryl Feuillet-Palma3; Nicolas Bergeal3; Ranjan Singh2
1ESPCI Paris PSL CNRS, France; 2SPMS - Nanyang Technological University, Singapore; 3LPEM - ESPCI Paris, France

Incorporating superconductors in terahertz metamaterials potentially provide unprecedented control over resonance features which has huge implications in the real-world technologies. In this work, we reveal an extremely sensitive Fano resonant High-Tc superconductor metamaterial fabricated using ion irradiation (II) technique which shows all-optical, ultrafast, switching and modulation of the sharp Fano resonances at extremely low optical pump fluences. The ultrasensitive nature of this metamaterial system is attributed to the presence of a dielectric material (non-superconducting YBCO) in the split gaps which thus results in the large field confinement in the subwavelength resonant structure.

11:00-12:30 - Th-AM-6 - Electronic SC Devices 2 - Room 269

Chairperson: Dmitry Turchinovich

11:00 Th-AM-6-1
40-GHz-Bandwidth Heterodyne Detection Of Terahertz-Waves By Waveguide-Input Fermi-Level Managed Barrier Diode Module

Hiroshi Ito1; Tadao Ishibashi2
1Kitasato University, Japan; 2NTT Electronics Techno Corporation, Japan

A waveguide-input Fermi-level managed barrier diode module was developed for broadband heterodyne detection. The fabricated module exhibited an intermediate frequency (IF) bandwidth of about 40 GHz and linear dependence of IF output power against input signal power. The minimum noise-equivalent power obtained was as low as 7e-18 W/Hz at around 300 GHz for a very low local oscillator power of about 3e-5 W

11:30 Th-AM-6-2
Numerical Study On Oscillation And Domain Formation In Series-Connected Resonant Tunneling Diodes

Hiroaki Yasuda1; Norihiko Sekine1; Iwao Hosako1; Tomoki Hiraoka2; Yuta Inose2; Takashi Arikawa2; Koichiro Takana2
1National Institute of Information and Communications Technology, Japan; 2Kyoto University, Japan

We performed simulations for oscillation of series-connected RTDs to realize higher output power. We found factors which determine whether oscillation or domain formation occurs. The variation of the fabricated RTD areas should be within a few percent to realize the oscillation.

11:45 Th-AM-6-3
Terahertz Emission From An Asymmetric Dual-Grating-Gate InGaAs High-Electron-Mobility Transistor Stimulated By Plasmonic Boom Instability

Tomotaka Hosotani; Takayuki Watanabe; Akira Satou; Taiichi Otsuji
Tohoku University, Japan

Asymmetric dual-grating-gate InGaAs high-electron-mobility transistors (ADGG-HEMTs) are studied as plasmonic terahertz (THz) emitters. We experimentally observed THz emission from a fabricated device at 110K. The spectra showed a broadband resonant emission under low d.c. channel currents reflecting radiation decay of thermally excited plasmons. With increasing the current and longitudinal electric field the emission was enhanced in a narrower spectral range suggesting promotion of plasmonic instability. Its threshold behavior suggests the occurrence of plasmonic-boom-type instability.

12:00 Th-AM-6-4
Realizing Asymmetric Boundary Conditions For Plasmonic THz Wave Generation In HEMTs

Bilal Barut1; Gregory R. Aizin2; Erik Einarsson3; Josep M. Jornet3; Takeyoshi Sugaya4; Jonathan P. Bird3
1Department of Physics, University at Buffalo, United States; 2Department of Physical Sciences, Kingsborough Community College, United States; 3Department of Electrical Engineering, University at Buffalo, United States; 4National Institute of Advanced Industrial Science and Technology (AIST), Japan

Devices utilizing plasma wave generation are promising candidates for the realization of compact solid-state sources, capable of operating efficiently at THz frequencies. In 1993, Dyakonov and Shur predicted the possibility of a plasma wave instability arising in HEMTs when a DC current is passed through their gated conducting channel. If the boundary conditions at the opposite ends of the channel are highly asymmetric, the amplitude of spontaneously excited plasma wave may increase exponentially. While significant experimental effort has focused on implementing plasmonic THz devices, the power radiated into free space has proven to be too weak for practical use due to the difficulty in creating asymmetric channel boundaries. In this work, we show that etching a constriction near the gated region of a HEMT can produce the high impedance required on the drain side of the channel, thus yielding the requisite asymmetry needed to trigger plasma wave amplification.

12:15 Th-AM-6-5
A New Approach To Achieve Gunn Effect For GaN Based THz Sources With High Power
Ahid S. Hajo1; Oktay Yilmazoglu1; Boraq Samodi1; Armin Dadgar2; Franko Küppers1; Thomas Kussorow1
1Technische Universität Darmstadt, Germany; 2Otto-von-Guericke-Universität Magdeburg, Germany

For the first time, Gunn effect is showed using a side- contact (SC) technology. Our THz Gunn source is based on 2 ÃZ¼m thick gallium nitride (GaN) with stable operation up to 22 V due to better heat sink and side contact technology. A diode current of about 1 A was achieved for high output power.

12:30-13:00 Award Ceremony - Amphi Lavoisier

13:00-14:00 - Lunch

14:00-16:00 Parallel sessions Th-PM1

14:00-16:00 - Th-PM1-1 - Imaging 2 - Amphi Lavoisier

Chairperson: Ginatras Valusis

14:00 Th-PM1-1-1
Terahertz Spatial Light Modulator Based On An Electrostatically Tunable Array Of Large Micromirrors

Jan Kappa1; Dominik Sokoluk1; Steffen Klingel2; Corey Shemelya1; Egbert Oesterschulze2; Marco Rahm1
1Technische Universität Kaiserslautern Department of Electrical and Computer Engineering, Germany; 2Technische Universität Kaiserslautern Department of Experimental Physics, Physics and Technology, Germany

We present a new type of terahertz spatial light modulator (THz-SLM) based on an array of large micromirrors. The electrostatically tunable micromirrors spatially modulate terahertz waves in a frequency range from 0.97 THz to 2.28 THz with a peak modulation contrast of 87% at 1.38 THz. The array consists of 768 micromirrors with each having a length of 220 Ã,µm and a width of 100 Ã,µm. The mirrors are grouped into 24 pixels. By application of a bias voltage, the pixels can be individually switched between a reflecting and scattering state, which allows spatial modulation of terahertz radiation.

14:30 Th-PM1-1-2
Towards Real-time THz Imaging With Single-pixel Detectors

Rayko Stantchev; Thierry Blu; Emma Pickwell-MacPherson
The department of Electronic Engineering, The Chinese University of Hong Kong, Hong Kong

For commercial acceptance, THz technology needs cheaper, more robust and quicker imaging modalities that do not sacrifice the time-resolving capabilities of THz-TDS systems. Single-pixel detectors with spatial light modulation imaging techniques offer a path to rapid, cheap and no-moving parts imaging systems. Here, by imaging in this modality, where we use a photoconductive antenna and a THz spatial modulator based on tailoring a semiconductor's Drude plasma frequency by spatial photoexcitation, we optimize this process by considering the modulation geometry. Finally, by considering the system's temporal response in post-processing, we show that one can reach a mask modulation rate of 20kHz, only limited by the digital micromirror (DMD) switch speeds.

14:45 Th-PM1-1-3
THz Multi-Layer Imaging Via Nonlinear Inverse Scattering

Arindam Bose1; Ajinkya Kadu2; Hassan Mansour3; Pu (Perry) Wang3; Petros Boufounos3; Philip Orlik3; Mojtaba Soltanalian1
1University of Illinois at Chicago; 2Utrecht University, Netherlands; 3MERL, United States

In this paper, to mitigate the nonlinear shadow effects in Terahertz time-domain spectroscopy (THz-TDS) multilayer imaging, we utilize a one-dimensional (1D) nonlinear model to capture the interaction between the dielectric permittivity profile and the THz wavefield and recover the multi-layer structure by solving a 1D nonlinear inverse scattering via an iterative and sequential optimization over frequency. Numerical results confirm the effectiveness of the proposed method.

15:00 Th-PM1-1-4
Handheld Telecentric THz-TDS Scanner Using Custom F-? Optics For Imaging Applications In Clinical Settings And Non-destructive Testing

Hassan Arbab; Zachery Harris; Arjun Virk
Stony Brook University, United States

We present a handheld THz-TDS scanner for use in clinical settings and non-destructive testing applications. The ASOPS scanner is based on a gimbaled galvanoscanner and custom-designed f-θ lenses to achieve telecentric imaging in a 3D-printed housing. We present imaging results from Bohler star calibration targets for determination of spatial resolution. We will also present non-destructive testing of airplane wing samples. Finally, the application of this scanner in clinical diagnosis of skin burns will be presented.

15:15 Th-PM1-1-5
Terahertz Subwavelength Resolution Imaging By Sampling Spatial Spectrum

Tie-Jun Huang; Li-Zheng Yin; Feng-Yuan Han; Jiang-Yu Liu; Yunhua Tan; Pu-Kun Liu
Peking University, China

In this work, an alternative method is proposed to realize terahertz far-field super-resolution imaging. Due the unique dispersive properties of the spoof surface plasmon (SSP), the spatial spectrum of the targets can be extracted and conserved by the adjacent SSP structure through a frequency canning operation. With the assist of a broadband coupler, the sampled information can be sent and retrieved in the far-filed. Then, the image with subwavelength resolution is constructed by inverse Fourier Transform. Although the resolution of 0.1ÃfŽÃ,» is verified, the resolution can be further enhanced by optimizing the SSP structure. This work may find applications in non-destructive testing and biomedical imaging.

15:30 Th-PM1-1-6
How To Spare The Phase Modulator In Fast-sweeping Coherent Cw THz Systems

Lars Liebermeister; Simon Nellen; Robert B. Kohlhaas; Steffen Breuer; Martin Schell; Bjoern Globisch
Fraunhofer Heinrich Hertz Institut, Germany

A new scheme for rapid coherent cw THz spectroscopy is presented achieving full phase information without active phase modulation. Through photomixing, the beating of two lasers drives the generation of the THz field. Due to the interferometric character of this technique, fast sweeping of one laser combined with a static delay-path results in continuous phase and amplitude modulation of the signal. A quadrature lock-in amplifier running at this modulation frequency detects amplitude and phase while reducing noise. This scheme allows for fully phase sensitive spectroscopy without the need of a phase modulator or an amplitude modulator.

15:45 Th-PM1-1-7
Location Of Objects Beyond The Horizon Line By Terahertz Surface Plasmons

Vasily Gerasimov1; Alexey Nikitin2; Alexey Lemzyakov1; Boris Knyazev1
1Budker Institute of nuclear physics SB RAS, Russian Federation; 2Scientific and Technological Center for Unique Instrumentation of RAS, Russian Federation

We report on the first experiments on the over-the-horizon location of objects on the conducting surface by means of terahertz (THz) surface plasmon polaritons (SPPs) generated by free-electron laser radiation with the wavelength λ=130 µm. The gold surface, guiding the SPPs, consisted of two flat faces 35 mm long each joined by a rounded edge with a radius of 10 mm. The intensity of SPPs reflected by the metal object placed on the surface at 3.5 cm beyond the horizon line depended on the height of the object in accordance with the distribution of the SPP field over the surface (a few mm or fractions of a mm). The distance, orientation, coordinates and height of an object beyond the horizon line can be determined using the THz SPP locator.

14:00-16:00 - Th-PM1-2 - Solid State 5 - Petit Amphi

Chairperson: Andrea Markelz

14:00 Th-PM1-2-1
Near-field THz Detection Of Phonon-polariton Modes In Thin Flakes Of Topological Insulator Materials: Bi2Se3 And Bi(Te1-x Sex)3

Eva Arianna Aurelia Pogna; Luca Salemi; Katia Garrasi; Leonardo Viti; Maria Caterina Giordano; Miriam Serena Vitiello
NEST, CNR-Nano, Italy

We report the study of phonon polaritons modes in thin crystalline flakes of Bi2Se3 and Bi2(Te1-x Sex)3 as a function of the flake thickness by means of two near-field THz techniques: phase resolved self-detection and THz time domain spectroscopy (TDS-SNOM). Background-free near-field imaging with nanoscale spatial resolution is demonstrated.

14:30 Th-PM1-2-2
Direct Comparison Between Multi-Dimensional Terahertz Vibrational Spectroscopies

Brittany E. Knighton; Megan F. Nielson; R. Tanner Hardy; Aldair Alejandro; Lauren M. Rawlings; Jeremy A. Johnson
Brigham Young University, United States

Multidimensional terahertz (THz) spectroscopy is a powerful tool for understanding nonlinear excitation, coherent energy flow, and coupling between collective degrees of freedom on ultrafast time scales. With extreme vibrational excitation using high-field THz light, 2D THz spectroscopy can reveal how anharmonic mode coupling results in coherent energy transfer and ascertain the excitation pathways behind nonlinear sample responses. We directly compare 2D THz-THz transmission measurements to 2D THz-THz-Raman measurements and explore evidence of anharmonic coupling between phonon modes in β-barium borate.

14:45 Th-PM1-2-3
Deriving Elastic Parameters From Lattice Vibrations In Copper (II) Acetylacetonate
Sara Dampf; Timothy Korter
Syracuse University, United States

Terahertz frequency vibrations exhibit characteristics that can be related to mechanical elastic parameters and yield insight into bulk physical properties. Through a combination of experimental low-frequency spectroscopy and solid-state density functional theory, specific vibrations can be used to determine elastic moduli. Applying this technique to a small metal-organic system, copper (II) acetylacetonate, provides new understanding of its unusual elastic behavior.

15:00 Th-PM1-2-4
Quantitative Analysis Of Minium And Vermilion Mixtures Using Low-Frequency
Vibrational Spectroscopy
Elyse Kleist; Timothy Korter
Syracuse University, United States

The non-invasive and non-destructive nature of low-frequency vibrational spectroscopy makes it an invaluable method for investigating historical pigments and artifacts. The terahertz and low-frequency Raman spectra of two pigments, minium and vermilion are presented here, along with quantum mechanical simulations of their structures and lattice vibrations. An analysis of pigment mixtures is also presented, along with the estimated limits of detection and quantitation for the specific experimental systems.

15:15 Th-PM1-2-5
Quantum And Classical Contributions To Spontaneous Scattering By Terahertz Phonon Polaritons At Cryogenic Temperatures
Tatiana Novikova; Kirill Kuznetsov; Galiya Kitaeva; Andrey Leontyev
Lomonosov Moscow State University, Faculty of Physics, Russian Federation

We consider using spontaneous light scattering by terahertz-frequency phonon polaritons as a source of quantum-correlated pairs of optical and terahertz photons. Frequency-angular distributions of the optical Stokes and anti-Stokes signal photons are measured in the wide range of the nonlinear crystal temperatures, 4 K - 300 K, and analyzed using the nonlinear Kirchhoff law. It is shown that cryogenic cooling enables to suppress contributions from thermal field fluctuations and to detect pure contributions from the quantum zero vacuum field fluctuations.

15:30 Th-PM1-2-6
Terahertz Vibrational Motions Dictate And Drive The Properties Of Advanced Materials

Michael Ruggiero
The University of Vermont, United States
Low-frequency (terahertz) vibrational motions often involve large amplitude displacements of entire molecules in the condensed phase. These vibrational pathways are critical to understanding and describing advanced material properties, including mechanical response, charge carrier dynamics, phase-transformation phenomena, and chemical stability, to name a few. In this work, the broad and pervasive nature of specific terahertz motions in such phenomena will be explored, and recent advances in using terahertz radiation to manipulate materials will be highlighted.

14:00-16:00 - Th-PM1-3 - THz Waveguides 1 - Room 151

Chairperson: Daniel Mittleman

14:00 Th-PM1-3-1
Evolution From Air-Cladded To Effective-Medium-Cladded Dielectric Waveguides

Weijie Gao1; Xiongbin Yu2; Masayuki Fujita2; Tadao Nagatsuma2; Christophe Fumeaux1; Withawat Withayachumnankul1
1Terahertz Engineering Laboratory, School of Electrical and Electronic Engineering, The University of, Australia; 2Graduate School of Engineering Science, Osaka University, Japan

Integrated guiding structures with low loss, low dispersion and broad bandwidth are demanded in high-performance terahertz systems. In this work, an effective-medium-cladded waveguide fabricated on a single high-resistivity silicon wafer is proposed for terahertz operation. The effective medium is realized by regularly perforating a silicon slab with a period in the subwavelength region. The simulated average attenuation coefficient is around 0.05 dB/cm over the operation frequency range from 220 GHz to 330 GHz for the E_11^x mode.

14:30 Th-PM1-3-2
Integrated Luneburg And Maxwell Fisheye Lenses For The Terahertz Range

Daniel Headland1; Withawat Withayachumnankul2; Masayuki Fujita1; Tadao Nagatsuma1
1Osaka University, Japan; 2The University of Adelaide, Australia

Micro-scale silicon photonic crystal waveguides show promise to realize efficient terahertz photonic circuits. Monolithically-integrated gradient-index optics expand the functionality of terahertz photonic crystal waveguide-based systems. We present two devices that leverage such micro-photonic integrated optics; a Luneburg lens-based multi-beam antenna and a Maxwell fisheye lens-based slab-mode beam launcher.

14:45 Th-PM1-3-3
Leaky Wave Antenna At 300 GHz In Silicon Micromachined Waveguide Technology

Dragos Dancila1; Bernhard Beuerle2; Umer Shah2; Joachim Oberhammer2; Anders Rydberg1
1Division of Solid-State Electronics, Uppsala University, Angstrom laboratoriet, Sweden; 2Division of Micro and Nanosystems, KTH School of Electrical Engineering and Computer, Sweden

A leaky wave antenna composed of eight slots in a gold metallised silicon micromachined waveguide was designed, fabricated and measured at 300 GHz. The measured results are in good agreement with the simulations.

15:00 Th-PM1-3-4
Spectroscopic Characterization Of 3D Printed THz Rectangular Polymer Waveguides

Xuan Liu; Kevin Kolpatzeck; Benedikt Friederich; Dilyan Damyanov; Lars Haering; Thorsten Schultze; Jan C. Balzer; Andreas Czylwik
Universität Duisburg-Essen, Germany

In this paper, rectangular polymer waveguides for single-mode operation at 140 GHz are designed, simulated, and fabricated by 3D printing technology. The propagating mode is characterized by determining the attenuation constant and the effective refractive index of the waveguide using THz frequencydomain spectroscopy. Moreover, the change of the mode pattern with frequency is observed by performing transversal scans of the far-field radiation pattern at the output of the waveguide.

15:15 Th-PM1-3-5
Fabrication Of Devices And Antennas For Millimeter-Wave And Terahertz Systems
Joseph Choonsup lee1; Maria Alonso-delPino1; Cecile Jung1; Imran Mehdi1; Goutam Chattopadhyay1; David Gonzalez-Ovejero2
1NASA JPL, United States; 2French National Centre for Scientific Research,CNRS, France

We have demonstrated corrugated horn antennas at 560 GHz fabricated with a deep reactive ion etching (DRIE) process on silicon. The measurement of two of the (2Ãfâ?"2) 560 GHz array antenna has shown that the return loss and directivity are 13 dB and 22 dB, respectively. All of the measured antennas had below -25 dB of the cross-polarization and symmetrical beam patterns. The silicon microfabrication technique enables us to build hundreds of horn antennas at once, allowing construction of multi-pixel heterodyne imagers and spectrometers at submillimeter wavelengths.

15:30 Th-PM1-3-6
Anomalous Blue-shift Of Terahertz Whispering-gallery Modes

Dominik Vogt1; Angus Jones1; Harald Schwefel2; Rainer Leonhardt1
1University of Auckland, New Zealand; 2University of Otago,New Zealand

We report on the first demonstration of an anomalous blue-shift of whispering-gallery modes (WGMs) using metallic substrates. The results allow for frequency tuning of WGMs essential for numerous applications, and establish novel insights into the anomalous blue-shift of WGM cavity systems.

15:45 Th-PM1-3-7
Micro Helical Antenna Made From Biological Algae Spirulina

Takashi Notake1; Tomokazu Iyoda2; Kaori Kamata3; Chiko Otani1; Hiroaki Minamide1
1RIKEN, Japan; 2Doshisha University, Japan; 3National Medical Defense College, Japan

Micro helical antennas whose resonance correspond to THz frequency region can be fabricated from biological algae spirulina via electroless metal coating. Radiation characteristics of the micro helical antenna are investigated by using THz near-field microscope. Both normal and end-fire mode radiations with different frequency characteristics can be successfully observed in real time.

14:00-16:00 - Th-PM1-4 - Nano-quantum Devices 2 - Room 101

Chairperson: Carlo Sirtori

14:00 Th-PM1-4-1
Magneto-transport Of 2DEGs Ultrastrongly Coupled To Vacuum Fields

Felice Appugliese1; Gian Lorenzo Paravicini-Bagliani1; Johan Andberger1; Nicola Bartolo2; Mattias Beck1; Thomas Ihn3; Klaus Ensslin3; Cristiano Ciuti2; Giacomo Scalari4; Jerome Faist4
1Institute for Quantum Electronics ETH Zurich, Switzerland; 2Laboratoire Matériaux et Phénomènes Quantiques, Université Paris Diderot, France; 3Laboratory for Solid State Physics ETH Zurich, Laboratory for Solid State Physics ETH Zurich, Switzerland; 4Institute for Quantum Electronics, Switzerland

In systems with strong light matter coupling, hybrid excitations, called polaritons, arise. We investigate the role of the electronic component of polaritons in the magneto-transport of a coupled light-matter system. We show that the coupling to a Terahertz (THz) resonator, even without external illumination, modifies the linear direct current resistivity. We also study the different contribution to the coupled system of localized and delocalized states, by looking at the magneto-transport under weak illumination.

14:30 Th-PM1-4-2
Plasmonic Nonlinearity In GaAs/In0.20Ga0.80As Core/shell Nanowires

Rakesh Rana; Leila Balaghi; Ivan Fotev; Harald Schneider; Manfred Helm; Emmanouil Dimakis; Alexej Pashkin
Helmholtz-Zentrum Dresden-Rossendorf, Germany

We have investigated the plasmonic response of GaAs/In0.20Ga0.80As core/shell nanowires driven resonantly by strong THz fields with the amplitude of few MV/cm. The plasmon mode exhibits a systematic redshift with the suppression of the spectral weight with the increase of the driving THz field. Interestingly, the scaling of the plasmon parameters does not follow the usual quadratic behavior, indicating an inhomogeneous intervalley electron scattering across the nanowire.

14:45 Th-PM1-4-3
An Ultrafast Semiconducting Nanowire THz Polarization Modulator

Djamshid Damry1; Sarwat Howe2; Jessica Boland3; Hannah Joyce4; Michael Johnston5
1University of Oxford, United Kingdom; 2University of Cambridge Enterprise, United Kingdom; 3University of Manchester, Photon Science Institute, United Kingdom; 4University of Cambridge, United Kingdom; 5University of Oxford, Clarendon Laboratory, Department of Physics, United Kingdom

In this work, we will demonstrate a novel ultrafast THz modulator based on GaAs semiconductor nanowires at very high THz bandwidth. The modulator devices were fabricated using a highly flexible and cheap substrate -- parylene-c. Through the use of multiple layers of this substrate, we show that for higher layers, a higher modulation depth is achieved without affecting the bandwidth over which the devices can operate. A terahertz air-plasma setup was built which allowed us to assess the devices over a broad range bandwidth of 0.1 THz -- 40 THz.

15:00 Th-PM1-4-4
Enhanced Performance Of InAsP Nanowires With Ultra-thin Passivation Layer

Stephanie Adeyemo1; Srabani Kar1; Yunyan Zhang2; Huiyun Liu2; Hannah Joyce1
1Electrical Engineering Division, Department of Engineering, University of Cambridge, United Kingdom; 2Department of Electronic and Electrical Engineering, University College London, United Kingdom

Surface passivation with a higher band gap shell has been shown to successfully reduce the density of surface states at the surface of nanowires. The effect of ultra-thin InP passivation layers of thicknesses ~3-5 nm coated on InAsP nanowires is investigated and compared to bare InAsP nanowires. The ultra-thin passivation exhibited an improvement in carrier lifetime and mobility by approximately a factor of 3. Surface recombination velocity was decreased by at least a factor of 3.

15:15 Th-PM1-4-5
THz Absorption In Graphene Quantum Dots

Sylvain Massabeau1; Juliette Mangeney1; Elisa Riccardi1; Michaël Rosticher1; Claire Berger2; Walter de Heer2; Sukhdeep Dhillon1; Robson Ferreira1
1Ecole Normale Supérieure, France; 2Georgia Institute of Technology, United States

We study the optical response of multilayer graphene quantum dots at THz frequencies. We fabricate 73 nm-diameter graphene quantum dots in an array of ~1mm2 size. We demonstrate optical absorbance of these graphene quantum dots from 0.5 to 5.7 THz and study the absorption dependence with the temperature from 4K to 300 K.

15:30 Th-PM1-4-6
Preparation Of The Quantum Correlated Optical-Terahertz Biphotons

Kirill Kuznetsov; Andrey Leontyev; Tatiana Novikova; Arthur Gayasarov; Vitaly Sultanov; Alexander Rudyak; Galiya Kitaeva
Lomonosov Moscow State University, Faculty of Physics, Russian Federation

We study the conditions necessary for generating non-classical optical-terahertz biphotons by means of spontaneous parametric down-conversion. Using a hot electron bolometer we demonstrate detection of the THz-frequency idler waves generated under parametric up- and down-conversion with a record low gain. Complete disappearance of the classical contribution has been observed at low temperatures. A second-order biphoton correlation function is analyzed.

15:45 Th-PM1-4-7
Pump - Probe THz Spectroscopy Study Of Electronic Properties Of Semiconductor Nanowires
Ivan Fotev; Leila Balaghi; Si Shan; Rene Huebner; Johannes Schmidt; Harald Schneider; Manfred Helm; Emmanouil Dimakis; Alexej Pashkin
Helmholtz-Zentrum Dresden-Rossendorf, Germany

THz radiation is a perfect tool for probing electrical properties of semiconductor nanostructures in a contactless way. When applied to semiconductor nanowires, THz probe pulses can drive the oscillations of photoexcited electrons and holes in the form of localized surface plasmon. We used optical pump -THz probe spectroscopy to study plasmonic response of charge carriers in GaAs/InxGa1-xAs core/shell nanowires. The carrier lifetimes are about 80-100 ps, depending on the shell composition and the photoexcitation level, while the extracted mobilities reach 3700 cm2/Vs at room temperature.

14:00-16:00 - Th-PM1-5 - Metamarials 6 - Room 162

Chairperson: Jaime Gomez-Rivas

14:00 Th-PM1-5-1

Optically Tunable All-Dielectric Broadband Terahertz Metamaterial Perfect Absorber
Xiaoguang Zhao1; Yue Wang1; Jacob Schalch2; Guangwu Duan1; Kevin Cremin2; Jingdi Zhang2; Chunxu Chen1; Richard Averitt2; Xin Zhang1
1Boston University, United States; 2University of California, San Diego, United States

We report a single-layer H-shaped all-silicon array to demonstrate tunable ultra-broadband terahertz wave absorption. Experiment and simulation reveal near unity absorption at the frequency of 1 THz, with a bandwidth of ÃfÆ'Ã?â?TÃfâ?sÃ,¢ÃfÆ'<Ãf¢ââ?s¬Ã, ÃfÆ'ââ,¬Å¡Ãfâ?sÃ,¼913 GHz for ÃfÆ'Ã?â?TÃfâ?sÃ,¢ÃfÆ'Ã,¢Ãf¢ââ,¬Å¡Ã,¬Ãfâ?sÃ,°ÃfÆ'ââ,¬Å¡Ãfâ?sÃ,Â¥90% absorbance. The absorption is optically tunable, exhibiting a resonance frequency blueshift by 420 GHz, while the peak absorbance remains over 99%. The dynamic response upon optical excitation depends upon the penetration depth of the pump beam in silicon, as demonstrated in simulations that take into account the depth dependence of the carrier concentration in the all-silicon metamaterial perfect absorber. The results unveil the tuning mechanisms in optically tunable all-silicon metamaterials and metasurfaces, guiding the development of functional all-dielectric functional terahertz devices, such as switches and modulators.

14:30 Th-PM1-5-2
Terahertz Broadband Independent Electrically Tuned Phase-shifter Based On Metamaterial With Mutual-coupling Magnetic Resonance
Tianyang Song1; Hongxin Zeng1; Feng Lan1; Ziqiang Yang1; Yaxin Zhang1; Zongjun Shi1; Luyang Wang1; Pinaki Mazumder2
1Terahertz Research Centre, University of Electronic Science and Technology of China, China; 2Department of Electrical Engineering and Computer Science, University of Michigan, United States

In this paper, a broadband terahertz phase-shifter based on metamaterial that can be independent electrically tuned for three-dimensional (3D) beam control is designed by integrating High Electron Mobility Transistor (HEMT) into a well-designed multi-layer structure unit. The variation of carrier density in the HEMT results in a transition of the resonant mode in the multilayer resonant structure. The change of magnetic enhancement and magnetic neutralization provide a phase shift of 180Ã,°Ã,±15Ã,° with a 20% bandwidth in 0.35-0.42 THz. This work facilitated the implementation of 3D terahertz beam control by digitally coding metasurfaces.

14:45 Th-PM1-5-3
Optical Reconfigurable Terahertz Devices Using Phase Change Materials

Maxime Pinaud1; Georges Humbert1; Sebastian Engelbrecht2; Lionel Merlat2; Bernd Fischer2; Aurelian Crunteanu1
1Xlim research institut, France; 2ISL, French-German Research Institute of Saint-Louis, France

Phase change materials (PCMs) have the ability to change their electrical and optical properties under electrical or optical excitations over a large frequency spectrum. These properties are attractive for developing future reconfigurable Terahertz (THz) devices. We report the demonstration of a THz device entirely fabricated with PCMs which can largely modify the transmission and polarization state of an incident THz wave using reversible phase changes in a GeTe material (insulating to metallic phase transition using optical excitations). Furthermore, we investigate the possibility to optically imprint grating-type GeTe crystalline structures within an amorphous GeTe film for further demonstrating reconfigurable THz devices.

15:00 Th-PM1-5-4
Demonstration Of Ultrafast THz Absorption Modulation In A Graphene-Based Thin Absorber

Anastasios Koulouklidis1; Anna Tasolamprou1; Christina Daskalaki1; Charalampos Mavidis1; George Kenanakis1; George Deligeorgis1; Zacharias Viskadourakis1; Polina Kuzhir2; Maria Kafesaki3; Eleftherios Economou4; Costas Soukoulis5; Stelios Tzortzakis3
1Institute of Electronic Structure and Laser (IESL)/ Foundation for Research and Technology-Hellas, Greece; 2Institute for Nuclear Problems/Belarusian State University, Belarus; 3Department of Materials Science and Technology/University of Crete, Greece; 4Department of Physics/University of Crete, Greece; 5Ames Laboratory and Department of Physics and Astronomy/Iowa State University, United States

We present the experimental and theoretical study of an ultrafast, optically tunable graphene-based thin film absorption modulator for operation in the THz regime. An ultrafast near-IR pulse induces the generation of hot carriers in the graphene sheet, consequently, reducing its conductivity with a decay time of 2.79 ps. As a result, a modulation of 40% in the THz absorption at 2.17 THz is observed in the structure.

15:15 Th-PM1-5-5
THz-induced Insulator-to-Metal Transition In Stacked VO2 Nano-slits

Bong Joo Kang1; Gregory Gaumann1; Nagla Numan2; Zoltan Ollmann1; Yannik Waeber1; Salvatore Bagiante3; Lorenzo Valzania4; Peter Zolliker4; Nicolas Émond5; Mohamed Chaker5; Erwin Hack4; Malik Maaza2; Thomas Feurer1
1University of Bern, Switzerland; 2University of South Africa, South Africa; 3Paul Scherrer Institute, Switzerland; 4Swiss Federal Laboratories Materials Science and Technology, Switzerland; 5Institut National de la Recherche Scientifique, Canada

We study the nonlinear, field dependent properties of stacked nano-slit array structures. Specifically, by measuring the field dependent THz transmission, we are able to resolve the insulator-to-metal transition of VO2 embedded in nano-slits. 2D simulations support the experimental data and allow for the calibration of the enhanced THz fields in the nano-slit volume.

15:30 Th-PM1-5-6
Electrically Tunable Graphene Metasurface For Multiband Superabsorption And Terahertz Sensing

MD SAIFUL ISLAM; Jakeya Sultana; Alex Dinovitser; Brian W.-H Ng; Derek Abbott
The University of Adelaide, Australia

We propose a plasmon induced graphene metasurface for terahertz absorption and sensing. The modelling and numerical analysis are carried out using CST microwave studio whereas a genetic algorithm (GA) is used to optimize the parameters. The metasurface is tunable by means of changing the graphene applied gate voltage. By tuning and exploiting its properties we demonstrate pa multiband absorption within the frequency of 0.1--2.25 THz with a graphene chemical potential (µc) of 0.2 eV. Further results show that, the superabsorber can be used as a sensor having maximum perfect absorption of 99.7%. The metasurface is polarization insensitive and can perform well for wide incident angles for both transverse electric and transverse magnetic field.

15:45 Th-PM1-5-7
Switching Of Optical Properties Of Ge2Sb2Te5 Phase Change Material In Terahertz Frequency Region

Kotaro Makino1; Kosaku Kato2; Yuta Saito1; Paul Fons1; Alexander Kolobov1; Junji Tominaga1; Takashi Nakano1; Makoto Nakajima2
1National Institute of Advanced Industrial Science and Technology (AIST), Japan; 2Osaka University, Japan

A reversible insulator-to-metal transition in phase change materials is expected to be used for a variety of optoelectronic devicess including terahertz (THz) applications. Here, we report on the phase-dependent changes in the optical properties of the thin films of Ge2Sb2Te5 (GST) phase change material. THz time domain spectroscopy (THz-TDS) measurement was carried out in amorphous and crystalline samples obtained by annealing at different temperatures and the optical properties of the GST films in the THz frequency range were characterized. It was found that the amorphous GST film is almost transparent for THz wave because of absence of free carrier. On the other hand, the crystalline GST films were found to absorb THz wave depending on the annealing temperature. The index of refraction was found to enhance with increasing annealing temperature. These properties are promising for THz wave devices such as programable amplitude modulator and plasmonic devices.

14:00-16:00 - Th-PM1-6 - Spintronics - Room 269

Chairperson: Jerzy Lusakowski

14:00 Th-PM1-6-1

Enhanced Spintronic Terahertz Emission In W/CoFeB Heterostructures Through Annealing Effect
Yang Gao1; Yanbin He1; Chandan Pandey2; Tianxiao Nie2; Chun Wang3; Deyin Kong1; Bo Wang3; Lianggong Wen2; Cunjun Ruan1; Jungang Miao1; Li Wang3; Yutong Li3; Weisheng Zhao2; Xiaojun Wu1
1School of Electronic and Information Engineering, Beihang University, China; 2Fert Beijing Institute, BDBC, and School of Microelectronics, China; 3Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, China

Three times enhancement of terahertz emission in W(2.2 nm)/CoFeB(2.0 nm) heterostructures through annealing are experimentally demonstrated. The possible mechanisms are qualitatively discussed and further verified in experiments.

14:30 Th-PM1-6-2
Role Of Magnetic Field In THz Emission From A Spintronic Source

Adam Shorrock1; Morgan Hibberd1; Thomas Thomson2; Paul Nutter2; Darren Graham1
1School of Physics and Astronomy & Photon Science Institute, The University of Manchester, United Kingdom; 2School of Computer Science, The University of Manchester, United Kingdom

We study the magnetic-field dependence of terahertz emission from a CoFeB/Pt bilayer spintronic emitter in order to ascertain the role of the magnetic structure on the emission process, determining that the THz emission closely follows conventional magnetic hysteresis loops.

14:45 Th-PM1-6-3
Impact Of Pump Wavelength On Terahertz Emission Of A Cavity-Enhanced Spintronic Trilayer

Rosamund Herapath1; Sam Hornett2; Tom Seifert3; Gerhard Jakob4; Mathias Klaui4; Jacopo Bertolotti2; Tobias Kampfrath3; Euan Hendry2
1University of Exeter, United Kingdom; 2University of Exeter, Department of Physics, United Kingdom; 3Fritz Haber Institute of the Max Planck Society, Germany; 4University of Mainz, Germany

Recent studies have shown that some spintronic THz emitters have high efficiencies for their nanoscale thicknesses. We investigate the pump-wavelength dependence of the THz generation from a novel spintronic THz emitter. We also add a weak cavity of dielectric overlayers, which reduces the transmission of the pump-wavelength and enhances the THz emission by a factor of four in intensity at a target wavelength.

15:00 Th-PM1-6-4
Effect Of DC Electric Field On The Emitted THz Signal For Antenna-Coupled Spintronics Emitters

Uttam Nandi1; Mohammed Abdel Aziz1; Samridh Jaiswal2; Gerhard Jakob2; Oliver Gückstock3; Reza Rouzegar3; Tom Seifert3; Mathias Kläui2; Tobias Kampfrath3; Sascha Preu1
1TU Darmstadt, Germany; 2Institute of Physics, Johannes Gutenberg University, Germany; 3Department of Physics, Freie Universität Berlin, Germany

Spintronics Sources are bias free THz sources with very high bandwidth and operates in the presence of an external magnetic field. We have deposited antenna structures on top of the spintronics material which facilitates us to apply an additional external electric field to these devices. The effect of applying simultaneous magnetic and electric fields on the emitted THz signal have been studied and presented in this paper.

15:15 Th-PM1-6-5
Emission Properties Of Structured Spintronic Terahertz Emitters

Christopher Rathje1; Rieke von Seggern1; Nina Meyer2; Christian Denker2; Markus Münzenberg2; Sascha Schäfer1
1University of Oldenburg, Germany; 2University of Greifswald, Germany

The inverse spin Hall effect offers a promising approach for the generation of intense broadband terahertz radiation from optically driven ultrathin magnetic samples. Here, we present our approach for tailoring the spatial and spectral emission properties of such spintronic thin film systems, utilizing terahertz resonator designs.

15:30 Th-PM1-6-6
Spintronic THz Generation Using A Silicon-based Fe/Pt Bilayer As The Radiation Source

Valynn Katrine Mag-usara1; Garik Torosyan2; Miezel Talara1; Jessica Afalla1; Joselito Muldera3; Hideaki Kitahara1; Laura Scheuer4; Dominik Sokoluk5; Evangelos Th. Papaioannou4; Marco Rahm5; René Beigang4; Masahiko Tani1
1Research Center for Development of Far-infrared Region, University of Fukui, Japan; 2Photonic Center Kaiserslautern, Germany; 3De La Salle University, Philippines; 4Department of Physics, Research Center OPTIMAS, Technische Universität Kaiserslautern, Germany; 5Department of Electrical and Computer Engineering, Research Center OPTIMAS, Technische Universität K, Germany

A spintronic bilayer structure of 2-nm Fe and 3-nm Pt was fabricated by molecular beam epitaxy on a Silicon substrate. We demonstrate that this Fe/Pt on Si heterostructure is an efficient and convenient alternative terahertz emitter particularly for systems which are driven by femtosecond fiber lasers with 1550-nm output wavelength.

15:45 Th-PM1-6-7
Photonic Structure Enhanced Spintronic Terahertz Emitter

Zheng Feng1; Dacheng Wang1; Haifeng Ding2; Jianwang Cai3; Wei Tan1
1Microsystem & Terahertz Research Center, CAEP, China; 2Nanjing University, China; 3Institute of Physics, Chinese Academy of Sciences, China

We demonstrate high performance spintronic terahertz emitters enabled by photonic structures. Metal-dielectric photonic crystal structures are employed to overcome the intrinsic limitation on laser absorption in individual ultrathin active layers. As the induced transient charge currents in each period are in phase, the magnitude of THz emissions are significantly enhanced with the increased laser absorption.

16:00-16:30 - Coffee Break

16:30-18:15 Parallel sessions Th-PM2

16:30-18:15 - Th-PM2-1 - Imaging 3 - Amphi Lavoisier

Chairperson: Matteo Perenzoni

16:30 Th-PM2-1-1
Imaging Of Thick Objects Using Silicon Bessel Zone Plates At 0.6 THz
Linas Minkevicius; Domas Jokubauskis; Irmantas Kasalynas; Sergejus Orlovas; Antanas Urbas; Gintaras Valusis
Center for Physical Sciences and Technol, Lithuania

Terahertz imaging of thick objects using the silicon-based Bessel zone plates for 0.6 THz range are presented. Bessel spatial profiles and focal depth characteristics are investigated both theoretically and experimentally and compared with the multilevel phase Fresnel lenses. Negligible influence of object position between the Bessel zone plates for imaging resolution is highlighted.

17:00 Th-PM2-1-2
High Resolution Lensless THz Imaging With An Ultrafast TDS System

Dilyan Damyanov1; Benedikt Friederich1; Kevin Kolpatzeck1; Xuan Liu1; Milad Yahyapour2; Nico Vieweg2; Anselm Deninger2; Thorsten Schultze1; Ingolf Willms1; Jan Balzer1
1University Duisburg-Essen/Chair of Communication Systems, Germany; 2TOPTICA Photonics AG, Germany

In this paper, we employ an ultrafast THz timedomain spectroscopy (TDS) system for computationally efficient imaging using a Kirchhoff migration algorithm. The imaging method makes use of uncollimated, unfocused terahertz beams, and eliminates the need for any opto-mechanical elements. Moreover, this method compensates for the low signal-to-noise ratio obtained with an uncollimated THz beam. We use a THz TDS system based on electronically controlled optical sampling (ECOPS), which achieves a measurement rate of 1600 traces per second. We validate the performance of the method with three different objects and show that object dimensions below 400 µm can be clearly resolved.

17:15 Th-PM2-1-3
Multi-Level Diffractive Lenses For Real-Time Long-Wave IR Imaging

Sourangsu Banerji; Monjurul Meen; Apratim Majumder; Fernando Guevara-Vasquez; Rajesh Menon; Berardi Sensale-Rodriguez
University of Utah, United States

Recently the field of metalenses has experienced an upsurge as evidenced by the growing number of publications in the area with each passing year. In-turn diffractive lenses have been used as thin-lenses since the late 19th century. Here, we show that multi-level diffractive lenses (MDLs), when appropriately designed, can perform comparably to metalenses. Furthermore, MDLs can be designed and fabricated with larger constituent features, making them accessible to low-cost, large area / volume manufacturing, which is generally challenging for metalenses in particular at IR and visible wavelengths. Based on this approach, we demonstrate computationally designed MDLs in real-time still and video imaging in the long-wave infrared regime (8 - 12 um).

17:30 Th-PM2-1-4
Terahertz Deep Learning Computed Tomography
Yi-Chun Hung1; Shang-Hua Yang2
1National Tsing-Hua University, Taiwan; 2Department of Electrical Engineering, National Tsing Hua University, Taiwan

We present a supervised terahertz deep learning computed tomography (THz DL-CT) system, which offers superior image quality compared with conventional THz CT method evaluated by 3D printed models. To the best of our knowledge, this is the first demonstration of a THz DL-CT system capable of visualizing hidden objects with multi-material systems. By utilizing THz DL-CT system, the benefit and study result from the field of deep learning can be taken to address the problem of low resolution in THz imaging.

17:45 Th-PM2-1-5
Sub-millimeter Spatial Resolution Terahertz Computed Tomography System Based On Differential Pulse Delay Method

Bo-Yi Wu; Shang-Hua Yang
National Tsing-Hua University, Taiwan

We present a terahertz time-domain spectroscopy 3D imaging algorithm, which offers superior image quality compared with conventional computed tomography method. This algorithm utilizes both amplitude and time information of terahertz pulses to enhance image spatial resolution. Moreover, the image quality of the proposed algorithm outperformed computed tomography with much fewer number of projections.

18:00 Th-PM2-1-6
Characterizing Depth Resolution And Range Of A Swept-source THz OCT

Yu Tokizane; Yoshikiyo Moriguchi; Hiroaki Minamide
RIKEN, Japan

An injection seeded terahertz (THz) parametric generator (is-TPG) is a high power and widely tunable THz-wave source which is promising instrument for a swept-source THz coherence tomography. In this paper, the depth resolution and the depth range are characterized using a narrow-linewidth is-TPG. The resolution of 0.2 mm is obtained in measurement and the range of 15 mm is calculated.

16:30-18:30 - Th-PM2-2 - Solid State 6 - Petit Amphi

Chairperson: Masahiko Tani

16:30 Th-PM2-2-1
Coherent Coupled-mode Phonon Emission In A Photoexcited Charge-density-wave System

Mark D. Thomson1; Fanqi Meng1; Kaneez Rabia1; Sander van Smaalen2; Hartmut G. Roskos1
1Goethe University Frankfurt, Germany; 2University of Bayreuth, Germany

Photoexcitation of the quasi-one-dimensional charge-density-wave (CDW) system, blue bronze (K0.3MoO3), with near-infrared femtosecond pulses, results in both a low-frequency, broadband THz surface emission from the photo-Dember effect, and a narrow-band emission from a TO phonon doublet centered at 1.5 THz below ~100 K in the CDW state. The polarization dependence of the phonon emission leads us to propose a surface-field/quadrupole excitation mechanism, distinct from the typical mechanisms for phonon emission in other materials. A coupled-oscillator model with a transient suppression of the mode coupling can reproduce the detailed temporal and spectral characteristics of the emission.

16:45 Th-PM2-2-2
Relaxation Times Of Arsenic Excited Donor States In Germanium

Roman Zhukavin1; Konstantin Kovalevsky1; Yulia Choporova2; Vasily Gerasimov2; Veniamin Tsyplenkov1; Boris Knyazev2; Sergey Pavlov3; Nikolay Abrosimov4; Heinz-Wilhelm Hübers3; Valery Shastin1
1Institute for Physics of Microstructures, Russian Federation; 2Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences, Russian Federation; 3Institute of Optical Sensor Systems, German Aerospace Center (DLR), Germany; 4Leibniz-Institut für Kristallzüchtung, Germany

Experimental investigations of the relaxation times in germanium doped by shallow arsenic donors at low temperatures have been performed with use of pump-probe technique. The dedicated setup utilizes terahertz radiation from the NovoFEL free electron laser. Relaxation times of several excited states have been measured. The values of measured lifetimes fall into nanosecond range. Experimental results are compared with theoretical calculations which take into account acoustic phonon assisted relaxation.

17:00 Th-PM2-2-3
Terahertz Spectroscopy On Myoglobin: Boson Peak And Fracton

Tatsuya Mori1; Leona Motoji1; Yasuhiro Fujii2; Suguru Kitani3; Akitoshi Koreeda2; Kentaro Shiraki1; Yohei Yamamoto1; Seiji Kojima1
1University of Tsukuba, Japan; 2Ritsumeikan University,Japan; 3Tokyo Institute of Technology, Japan

Terahertz time-domain spectroscopy has been applied to protein myoglobin dried sample. The boson peak (BP) which is a universal excitation of disordered system has been detected around 0.5 THz. While, fracton will be a universal excitation in the self-similar structure, and it has been observed above the BP frequency. How the fracton appear in the infrared spectrum is explained using the fracton model and the linear response theory for amorphous materials.

17:15 Th-PM2-2-4
Longitudinal Optical Phonon Resonating Dipole Radiation From Metal- Semiconductor Composite Structures And Quantum Interference
Yoshihiro Ishitani; Keisuke Ebisawa; Daichi Tanaka; Nozomi Aihara; Bei Ma; Ken Morita
Chiba University, Japan

Selective thermal emission at 8.5 THz with a line width of 0.4 THz at 628 K is obtained by heating Au-GaAs mesa-type line and space structures. This emission demonstrates a characteristic polar radiation distribution of electric dipoles and a wavelength independent of the structure size or the direction of emission; thus, it is ascribed to thermally generated electric dipoles resonating with the longitudinal (LO) phonon energy. We have also observed two peaks for two LO modes in alloy semiconductors. These features are different from the radiation properties of interface phonon polaritons or electronic systems such as intersubband transitions of quantum wells. Further, quantum interference of two LO modes and a continuum electronic intervalence band transition based on Fano effect is observed for p-GaInP and optically excited (at the Γ pint) indirect transition type u-AlGaAs. These phenomena reveal the feasibility of emission based on electromagnetically induced transparency at LO phonon modes.

17:30 Th-PM2-2-5
Towards A General Rule Guiding THz Mode Assignment In Molecular Crystals

FENG ZHANG1; Hong-Wei Wang2; Keisuke Tominaga1; Michitoshi Hayashi2; Tetsuo Sasaki3
1Molecular Photoscience Research Center, Kobe University, Japan; 2Center for Condensed Matter Sciences, National Taiwan University, Taiwan; 3Research Institute of Electronics, Shizuoka University, Japan

On the basis of the quantitaive analyses of a set of prototype molecular crystals, we have verified a correlation relationship between the nature of THz modes and molecular conformational flexibility around the potential minimum. A more flexible backbone tends to lead to a more extensive distribution of intramolecular vibrations in the THz frequency region, and vice versa.

17:45 Th-PM2-2-6
THz Surface Phonon Polariton Generation In GaP Photonic Waveguide

Alejandro Lorenzo-Ruiz; Yoan Léger; Charles Cornet; Alexandre Beck
Institut FOTON / INSA Rennes, France

Generation of THz wave using surface phonon polariton and difference frequency generation in GaP stripe is investigated. Here, we present our preliminary results and show that mixing a TE and a TM mid-IR modes propagating along a [100] crystal axis is more efficient than the usual optical configuration along a [110] axis under transverse pump modes.

18:00 Th-PM2-2-7
Simulation And Assignment Of The Terahertz Spectra Of Enalapril Maleate Cocrystal Polymorphs

Margaret Davis1; Mizuki Mohara2; Kei Shimura2; Timothy Korter1
1Syracuse University, Department of Chemistry, United States; 2Hitachi High-Technologies Corp., Japan

Identification of crystalline drug polymorphs using terahertz spectroscopy is a powerful approach for the non-destructive and non-invasive characterization of solid pharmaceuticals. However, a complete understanding of the terahertz spectra of molecular solids is challenging to obtain due to the complex vibrational motions found at low frequencies. Unambiguous assignments of the observed spectral features can be achieved through fully quantum mechanical simulations of crystal structures and lattice vibrations. The terahertz spectrum of enalapril maleate is presented here to demonstrate that even large pharmaceuticals can be successfully modeled using rigorous solid-state density functional theory, including cocrystalline solids comprised of multiple distinct species

16:30-18:15 - Th-PM2-3 - THz Waveguides 2 - Room 151

Chairperson: Shriganesh Prabhu

16:30 Th-PM2-3-1

Silicon Gradient Refractive Index Lens For Millimeter Wave Radiometers
Pekka Pursula; Antti Lamminen; Rami Mannila; Kirsi Tappura; Jaakko Saarilahti
VTT Technical Research Centre of Finland, Finland

We propose a radiometer receiver array based on a silicon microlens array and MMIC detectors at 200 - 250 GHz. The paper describes the array concept and details microlens development. Planar Gradient Refractive Index (GRIN) lenses have been chosen for the array. Fabrication process based on DRIE etching of silicon has been developed, and lenses designed. The first measurement results of the lens are presented.

17:00 Th-PM2-3-2
THz Cavity Based On Confined Tamm Modes

Simon Messelot1; José Palomo1; Clémentine Symonds2; Joël Bellessa2; Jérôme Tignon1; Sukhdeep Dhillon1; Juliette Mangeney1
1ENS Paris, France; 2Université Claude Bernard Lyon 1, France

Resonators with high quality factor and small mode volume are very attractive for many applications in the THz frequency range. Here, we develop a novel THz cavity based on the Tamm modes that combines a distributed Bragg Reflector (DBR) and a metallic mirror. We demonstrate a quality factor higher than 80 at 0.91THz and good confinement properties. We show that the use of a metallic mirror enables the exploration of original properties such as frequency tuning, over 30%, using sub-lambda periodic gold strip mirror.

17:15 Th-PM2-3-3
Single Zone Fresnel Dielectric Plate Antenna
Arsen Hakhoumian1; Armen Sargsyan2
1Institute of Radiophysics and Electronics NAS RA, Armenia; 2Yerevan State University, Armenia

It is shown that simple dielectric disk with proper chosen refractive index, radius and thickness operate as lens and can increase for more than 10 dB directivity of the antenna couple detectors placed at the focal plane.

17:30 Th-PM2-3-4
Radiation Pattern Measurements Of A Silicon-lens Horn Antenna

Kevin Froberger; Cybelle Belem Goncalves; Guillaume Ducounau; Jean-Francois Lampin
Institute of Electronics Microelectronics and Nanotechnology CNRS UMR 8520, France

We present the measurements realized on a pyramidal shape piece of silicon designed in order to be metalized to become a silicon lens TEM horn antenna (Si-lens HA). The antenna was designed for the emission of terahertz radiation up to several hundreds of GHz. Simulations of the radiation of the silicon shape are also presented.

17:45 Th-PM2-3-5
A Broadband Polarization-rotating Antipodal Vivaldi Antenna For Improved Far-field Properties Of Terahertz Quantum Cascade Lasers
Urban Senica; Elena Mavrona; Tudor Olariu; Andres Forrer; Mattias Beck; Jérôme Faist; Giacomo Scalari
ETH Zurich, Switzerland

Double metal waveguide based terahertz quantum cascade lasers have excellent properties in terms of compactness, large bandwidth and low waveguide dispersion. However, as they confine the optical mode to subwavelength dimensions, their far-field is highly divergent. Our antipodal Vivaldi antenna is designed to produce a single-lobed far-field pattern with a beam width of less than 20°, spanning over two octaves in frequency (1.5-4.5 THz). Far-field measurements agree well with numerical simulations.

18:00 Th-PM2-3-6
Terahertz Helical Antenna Based On Celery Stalks

Carlito Ponseca1; Arunas Krotkus2
1Linkoping University, Sweden; 2Center for Physical Sciences and Technology, Lithuania

We decorate cellulose-based helices retrieved from the plant celery with a conductive poly(4-(2,3-dihydrothieno [3,4-b]-[1,4]dioxin-2-yl-methoxy)-1-butanesulfonate (PEDOT-S). A broad resonance peaked at 1 THz was obtained, consistent with electromagnetic models. As helical antennas, it was shown that both axial and normal modes are present, which are correlated to the orientation and antenna electrical lengths of the coated helices. This work opens the possibility of designing tunable terahertz antennas through simple control of their dimensions and orientation.

16:30-18:15 - Th-PM2-4 - Instrum. Biology 2 - Room 101

Chairperson: Axel Zeitler

16:30 Th-PM2-4-1
Terahertz-Conductivity In Biological Nanowire-Networks

Jens Neu; Sophia M. Yi; Yangqi Gu; Patrick O'Brien; Vishok Srikanth; Dennis Vu; Charles A. Schmuttenmaer; Nikhil S. Malvankar
Yale University, United States

I will present our ongoing research exploring the origin of conductivity in bacterially grown nanowires. These nanowires have a diameter of 2-4 nm and are several micrometer long, and exhibit THz and DC conductivity. Temperature resolved measurements revealed a metal-like behavior, the first time such a behavior was detected in any biological material. Furthermore, I will present preliminary results on photoconductivity in this material system.

17:00 Th-PM2-4-2
Identifying Endogenous Biomarker In Renal Fibrosis By Terahertz Spectroscopy

Yan Peng1; Jieli Huang2; Jie Luo1; Chen Yu2; Yiming Zhu1
1University of Shanghai for Science and Technology, China; 2Department of Nephrology, Tongji Hospital, China

Renal fibrosis is an important pathological change of chronic renal disease, here we demonstrate that the terahertz spectroscopy can be used to identify the endogenous biomarker in renal fibrosis, which have three absorption peaks at 0.64THz, 1.02THz, 1.82THz. Substantially based on the tests of the UUO rat models and real human renal fibrosis tissues, we quantify the different stages. These results show that terahertz spectroscopy exhibits much higher sensitivity than other biomedical methods, and has great potential of the early diagnosis and accurate stage evaluations of human renal fibrosis in clinic.

17:15 Th-PM2-4-3
Comparison Between Effective Medium Theory Models For Biological Tissues In The THz Range
Goretti Guadalupe Hernandez Cardoso; Enrique Castro Camus
Centro de Investigaciones en Optica, A. C., Mexico

In this work, we present the comparison of three effective medium theory models for obtaining the dielectric function of biological tissue in the terahertz range

17:30 Th-PM2-4-3
Controlled Hydration In Epidermal Ridges Probed By THz Time-Domain Spectroscopy

Seoung-Mok Yum1; In-Keun Baek2; Dongpyo Hong1; Seontae Kim1; Kihoon Eom1; Jeongmin Jang1; Seonmyeong Kim1; Matlabjon Sattorov1; Min-Geol Lee3; Sungwan Kim1; Michael Adams4; Gun-Sik Park1
1Seoul National University, Republic of Korea; 2Mechatronics R&D Center, Samsung Electronic Co.,Ltd., Republic of Korea; 3Yonsei University, Republic of Korea; 4University of Birmingham, United Kingdom

Fingerprints are common to humans, primates, and koalas but how their role in grip activities is poorly understood. Here, we reveal that the fingerprints control the hydration level of the fingertip, as required for precision gripping, by ultimately maximizing the friction. Electromagnetic waves with frequencies in the megahertz, terahertz, infrared, and visible ranges were used to identify the hydrodynamics in fingerprints, which lead to the steady-state hydration condition in 'dry' and 'wet' conditions. The results suggest that the fingerprint structure functions as a moisture channel for facilitating precision grip.

17:45 Th-PM2-4-5
Optical Properties Of Active Pharmaceutical Ingredients in Terahertz Region

Yusuf Samet Aytekin1; Mustafa Kokturk2; Adam Zaczek3; Timothy M. Korter3; Edwin J. Heilweil4; Okan Esenturk1
1Middle East Technical University, Turkey; 2Nobel İlaç Sanayi, Turkey; 3Department of Chemistry, Syracuse University, Turkey; 4Engineering Physics Division, National Institute of Standards and Technology, United States

In this study Terahertz (THz) spectra of several commonly used active pharmaceutical ingredients are reported. Results showed that all the API's had unique bands associated with the structures allowing to analyse both qualitatively and quantitatively. The liq. nitrogen temperature and solid state and gas phase theoretical analysis of meloxicam have also been carried out. In addition, the transparency of the drug packaging materials like plastic blisters, cartons were checked to see the technique's ability for in situ nondestructive penetrating analysis

18:00 Th-PM2-4-6
Probing Living Cells Permeabilization Dynamics By Terahertz Attenuated Total Reflectance

Guilhem Gallot1; Xiujun Zheng1; Marianne Grognot1; Antoine Azan2; Tomas Garcia-Sanchez2; Lucie Deschamps2; Lluis Mir2
1Ecole polytechnique, France; 2Institut Gustave Roussy, VAT, Université Paris-Sud, France

We present terahertz Attenuated Total Reflectance (ATR) dynamics measurements of cytoplasm leakage in live epithelial cells, after permeabilization by detergent or electropermeabilization, and analytical models for the transport of non-permeant molecules through the cytosol membrane

16:30-18:15 - Th-PM2-5 - FEL 2 - Room 162

Chairperson: In Hyung Baek

16:30 Th-PM2-5-1

Infrared And THz At The National Synchrotron Light Source II
G Lawrence Carr
Brookhaven National Laboratory, United States

The first NSLS-II beamline for infrared and THz spectroscopy recently began operations. The design incorporates features for reaching from the near-UV (~40,000 cm-1) to millimeter waves (~2 cm-1). The high brilliance synchrotron source will be used for a variety of spectroscopic techniques including microspectroscopy, magnetospectroscopy, ellipsometry and materials under extreme pressures and temperatures. Interestingly, the intrinsically short electron bunches (~15 ps rms) results in stable coherent radiation to be observed down to 5 GHz during normal operations.

17:00 Th-PM2-5-2
Coherency And Monochromaticity Of The Terahertz NovoFEL
Vitaly Kubarev; Yaroslav Getmanov; Oleg Shevchenko
Budker Institute of Nuclear Physics, Russian Federation

The coherency and monochromaticity of the terahertz Novosibirsk free-electron laser (NovoFEL) were measured by a special novel method using an ultra-long resonance waveguide vacuum Fabry-Perot interferometer. The coherency length and time were not less than 7 km and 25 µs, respectively. The monochromaticity of the comb spectral structure of the NovoFEL radiation at a wavelength of 164 µm was not worse than 2.2E-8. We are going to use the NovoFEL radiation for high-resolution comb spectroscopy and creation of a high-power ultra-monochromatic tunable terahertz source.

17:30 Th-PM2-5-3
Electron-doped SiGe Quantum Well Terahertz Emitters Pumped By FEL Pulses

Chiara Ciano1; Michele Montanari1; Luca Persichetti1; Luciana Di Gaspare1; Michele Virgilio2; Luigi Bagolini2; Giovanni Capellini3; Marvin Zoellner3; Oliver Skibitzki3; David Stark4; Giacomo Scalari4; Jérôme Faist4; Douglas Paul5; Kirsty Rew5; Thomas Grange6; Stefan Birner6; Alexej Pashkin7; Manfred Helm7; Leonetta Baldassarre8; Michele Ortolani8; Monica De Seta1
1University of Roma Tre, Italy; 2Università di Pisa, Italy; 3IHP-Innovations for High Performance Microelectronics, Germany; 4ETH Zurich - Institute for Quantum Electronics, Switzerland; 5School of Engineering - University of Glasgow, United Kingdom; 6Nextnano GmbH, Germany; 7Helmholtz-Zentrum Dresden-Rossendorf, Germany; 8Sapienza università di Roma, Italy

We explore saturable absorption and terahertz photoluminescence in a set of n-doped Ge/SiGe asymmetric coupled quantum wells, designed as three-level systems (i.e. quantum fountain). We generate a non-equilibrium population by optical pumping using picosecond pulses from a free-electron laser and characterize this effect by measuring absorption as a function of the pump intensity.

17:45 Th-PM2-5-4
Spatio-temporal Analysis Of Terahertz Electric Field Of Coherent Transition Radiation

Koichi Kan1; Masao Gohdo2; Jinfeng Yang2; Yoichi Yoshida2
1The Institute of Scientific and Industrial Research (ISIR), Japan; 2The Institute of Scientific and Industrial Research (ISIR), Osaka University, Japan

The Institute of Scientific and Industrial Research (ISIR), Osaka University, 8-1 Mihogaoka, Japan
Generation of femtosecond electron bunches has been investigated for a light source based on electron bunches and improvement of time resolution in time-resolved measurements. In this study, spatio-temporal analysis of terahertz (THz) electric field of coherent transition radiation (CTR) was conducted using a photoconductive antenna (PCA) with radial microstructures. The PCA was moved for spatial resolution of CTR measurement. An optical delay for a femtosecond laser enabled temporal resolution.

18:00 Th-PM2-5-5
Terahertz Coherent Synchrotron Radiation: Ultrafast Characterization And Control At Synchrotron SOLEIL

Clément Evain1; Christophe Szwaj1; Serge Bielawski1; Eléonore Roussel1; Jean Rodriguez1; Marc Le Parquier1; Marie-Agnès Tordeux2; Fernand Ribeiro2; Marie Labat2; Nicolas Hubert2; Jean-Blaise Brubach2; Laurent Manceron2; Pascale Roy2
1Univ. Lille, CNRS, UMR 8523 - PhLAM - Physique des Lasers, Atomes et Molécules, France; 2Synchrotron SOLEIL, France

We present resent results on the characterization and control of the coherent terahertz pulses emitted by synchrotron radiation facilities. We first show novel ultrafast single-shot measurements techniques now allow these sources to be fully characterized in a pulse-by-pulse basis [1]. Then we present a novel feedback method tat enables the dynamics of these sources to be fully controlled [2]. This opens the way to novel sources of stable THz radiation, and to high repetition-rate spectroscopic applications.

16:30-18:15 - Th-PM2-6 - Near-field 2 - Room 269

Chairperson: Oleg Mitrofanov

16:30 Th-PM2-6-1

Difference Mid-IR Nanospectroscopy On Individual Patches Of Purple Membranes: The Proton Pump Activity Of Bacteriorhodopsin at The Nanoscale
Valeria Giliberti1; Raffaella Polito2; Eglof Ritter3; Matthias Broser3; Peter Hegemann3; Ljiljana Puskar4; Ulrich Schade4; Laura Zanetti-Polzi5; Isabella Daidone5; Stefano Corni6; Francesco Rusconi7; Paolo Biagioni7; Leonetta Baldassarre2; Michele Ortolani2
1Instituto Italiano di Tecnologia - Center for Life NanoScience, Italy; 2Department of Physics, Sapienza University of Rome, Italy; 3Humboldt-Universität zu Berlin, Institut für Biologie, Germany; 4Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Germany; 5Department of Physical and Chemical Sciences, University of L'Aquila, Italy; 6Department of Chemical Sciences, University of Padova, Italy; 7Dipartimento di Fisica, Politecnico di Milano, Italy

Conformational changes of the light-sensitive membrane receptor and proton pump bacteriorhodopsin is investigated by tip-enhanced mid-infrared nanospectroscopy on individual cell membrane patches of less than 500 nm2 area, with a dramatic increase of sensitivity (in terms of number of probed molecules) compared with standard mid-IR spectroscopy.

17:00 Th-PM2-6-2
Characterization Of Thin Film Materials Using Near Field THz Imaging.
Fatemeh Amirkhan1; Ryoichi Sakata2; Kenji Takiguchi2; Takashi Arikawa2; Tsuneyuki Ozaki3; Koichiro Tanaka2; François Blanchard1
1École de technologie supérieure (ETS), Département of Electrical Engineering, Canada; 2Kyoto University, Department of Physics, Japan; 3Insitut national de la recherche scientifique, Énergie Matériaux Télécommunications (INRS-EMT), Canada

We demonstrate a new technique for characterizing thin film electro- and/or magneto-optic materials. This method is based on resolving the electric and/or magnetic field distributions in the near-field region of a split ring resonator (SRR) designed for the terahertz (THz) frequency range. Our simulations are supported experimentally by THz near-field imaging of SRRs directly patterned in contact with a thin-film lithium niobate crystal as a sensor. Furthermore, we analytically present the effect of the various polarization of applied electric field and calculate the sensitivity of the sensor through different probe beam polarizations.

17:15 Th-PM2-6-3
Probe-Sample Interaction In Aperture-type THz Near-Field Microscopy Of Complementary Resonators

Lucy Hale1; Janine Keller2; Tom Siday1; Rodolfo Hermans1; Johannes Haase3; John Reno4; Igal Brener4; Giacomo Scalari2; Jérôme Faist2; Oleg Mitrofanov5
1University College London, United Kingdom; 2Eidgenössische Technische Hochschule Zürich (ETH), Institute of Quantum Electronics, Switzerland; 3Paul Scherrer Institute, Switzerland; 4Sandia National Laboratories, Center for Integrated Nanotechnologies, United States; 5University College London, United Kingdom

Subwavelength complementary metallic resonators operating in the terahertz (THz) regime are investigated with aperture near-field microscopy and spectroscopy. In contrast to far-field methods, the spectra of individual isolated resonators can be retrieved. We find that we can experimentally gain spectral information without modifying the spectral properties of the resonator with the aperture-type near-field probe by operating it at a separation distance greater than 10 µm.

17:30 Th-PM2-6-4
Non-invasive Local (photo)conductivity Measurements Of Metallic And semiconductor Nanowires In The Near-field

Niels van Hoof1; Stan ter Huurne1; Matteo Parente2; Andrea Baldi2; Jaime Gomez Rivas1
1Eindhoven University of Technology, Netherlands; 2Dutch Institute For Fundamental Energy Research, Netherlands

Here, we show a THz near-field technique capable of measuring the characteristics of (semi)-conductive samples with a spatial resolution of a few tens of microns. This resolution will enable local (photo)conductivity measurements of active photonic devices such as solar cells and LEDs. In this work, we investigate ensembles of nanowires and asses their conductive properties. These nanowires can be produced in alloys and crystallographic orientations that are not achievable in nature, and with this technique we are able investigate the inhomogeneities of these type of systems.

17:45 Th-PM2-6-5
Efficiency Enhancement Of Scattering Near-Field Probes

Tom Siday; Oleg Mitrofanov
University College London, Electronic and Electrical Engineering, United Kingdom

THz near-field microscopy. We fabricate the probes by placing an indium 'antenna' directly on the tine of a quartz tuning fork (QTF), which we use as an atomic force microscope (AFM) probe in tapping mode. THz time-domain spectroscopy (TDS) of the THz field scattered from the probe shows that the scattering efficiency of the indium antenna exhibits resonant enhancement determined by the antenna length. These resonant scattering probes can enable THz near-field imaging applications where THz contrast is weak, such as 2D materials or biological systems.

18:00 Th-PM2-6-6
THz Near-field Inspection Of Metamaterials For Bio-sensing Applications Featuring Single-resonator Read-out Capability

Simon Sawallich1; Alexander Michalski1; Bartos Chmielak2; Ulrich Plachetka2; Michael Nagel1; Max C. Lemme3
1Protemics GmbH, Germany; 2AMO GmbH, Germany; 3RWTH Aachen University, Chair of Electronic Devices, Germany

We present contact-free Terahertz (THz) near-field measurements with microscopic resolution at meta-surfaces built from bow-tie resonators with broad spectral response and localized THz field enhancement. We will demonstrate single resonator read-out on wafer-scale measurement areas and the application as functionalized bio-sensor.

18:15-19:30 - Poster session - Th-Po4 - Room 8

Th-Po4-1
Comparison Of Mathematical Models For The Calculation Of Optical Properties Of Composite Medium In The Terahertz Regime

Ravshanjon Nazarov; Mikhail Khodzitskiy; Tianmiao Zhang
ITMO University, Russian Federation

Composite mediums are being used broadly nowadays. To design a desired composite medium, its theoretical properties should be calculated beforehand so its behavior can be expected. To find out the proper calculation methods in the terahertz regime, several mathematical models were used to calculate the theoretical optical properties of different composite materials. These properties were compared with the experiment data which were obtained from terahertz time-domain spectroscopy or from the reference papers. The result shows that to choose reliable mathematical model, the shape and size of each component need to be taken into account.

Th-Po4-2
Ferromagnetic Resonance In 3D-printing Hexagonal Ferrite BaFe12O19 Composite At The EHF Frequency Range

Alexander Badin; Grigorii Kuleshov; Victor Zhuravlev; Grigorii Dunaevskii; Kseniya Simonova; Kirill Dorozhkin; Dmitriy Bodazhkov
National Research Tomsk state University, Russian Federation

Today materials with desired electrophysical properties for 3D-printing by fused deposition modeling (FDM) are improved, their scope of application is expanding. The composite filaments based on inclusions of modified carbon, ferrites, metals and polymers [1-3] are being developed. Of particular interest is the creation of composites for 3D-printers based on acrylonitrile butadiene styrene (ABS) with inclusions of hexagonal M-type ferrite BaFe12O19 (ABS/BaFe12O19), which has a region of natural ferromagnetic resonance (NFMR) in the EHF range [4]. Thus, this composite filament can be used for the manufacture of frequencyselective absorbing coatings of any geometry by the additive layer-by-layer. Results of research of electromagnetic response of 3D-printing hexagonal ferrite BaFe12O19 composite at frequency range 34-250 GHz at room temperature are presented. Region of natural ferromagnetic resonance near 46.5 GHz was found. The possibility of creating a 3D-printing frequency selective shielding's based on the developed material is shown.

Th-Po4-3
Evaluation Of Ga2O3 Surface Potential Using Laser THz Emission Microscopy

Jian Hao1; Gong Chen1; Tatsuhiko Nishimura2; Hidetoshi Nakanishi2; Hironaru Murakami1; Masayoshi Tonouchi1; Iwao Kawayama1
1Osaka University, Osaka University, Japan; 2SCREEN Holdings, Japan

We have measured terahertz emissions form (010) and (-201) surfaces of ?-Ga2O3 that is recently attracting significant attention as a candidate for next generation power electronics. The surfaces of Ga2O3 were systematically investigated using laser THz emission microscopy and the results showed clear dependences of THz waveforms on carrier concentrations and surface orientations.

Th-Po4-4
Extrinsic Absorption In Spark Plasma Sintered Zr0.8Sn0.2TiO4 Ceramics Investigated By Terahertz Time-Domain Spectroscopy

Liviu Nedelcu; Mihail Burdusel; Mihai-Alexandru Grigoroscuta; Cezar Dragos Geambasu; Marian Gabriel Banciu; Petre Badica
National Institute of Materials Physics, Romania

Solid-state reaction synthesized Zr0.8Sn0.2TiO3 powders have been compacted by spark plasma sintering. In order to reduce the oxygen vacancies, the sintered samples were annealed ex-situ in air. Single-phase ceramics with different amount of oxygen vacancies and, consequently, different extrinsic absorption were investigated by terahertz time-domain spectroscopy. The results showed that the terahertz spectroscopy is a suitable technique for improving the properties of the spark plasma sintered materials.

Th-Po4-5
Comparison Of THz Spectroscopy Measurements Of Carbon Nanotubes Embedded In Polymer Matrices

Miguel Ángel Báez1; Raquel Llorens2; Borja Vidal1
1Universidad Politécnica de Valencia, Spain; 2AIMPLAS, Spain

Terahertz spectroscopy is used to obtain the optical parameters of polypropilene samples with different concentrations of multi walled carbon nanotubes. Results are put in context with previous works utilizing other kinds of polymer matrixes and an noticeable discrepancy in the behavior of attenuation with increasing loading content is found.

Th-Po4-6
A THz View On Magnetization Dynamics: Opportunities From The THz Userfacility TELBE

Nilesh Awari1; Zhe Wang1; J-C J-C Deinert11; Min Chen1; Bert Green1; I Ilyakov1; S Germansky1; T V A G de Oliveira1; A Deac1; M. Gensch2; S Kovalev1
1Helmholtz-Zentrum Dresden Rossendorf, Helmholtz-Zentrum Dresden Rossendorf, Bautzner Landstrasse, Germany; 2Technische Universität Berlin, Germany, Technische Universität Berlin, Germany, Berlin, Germany

In this contribution, we discuss the opportunities arising from the spectrally dense, narrow band, tunable, high repetition rate THz source; TELBE; which recently started user operation. The user facility includes an end station for transient Faraday/MOKE and THz emission spectroscopy and is also equipped with a superconducting split-coil cryo-magnet. Thereby the dynamics of selectively driven resonances in the frequency range between 0.1 and 1.2 THz can be followed with a femtosecond sub THz-cycle time resolution at temperatures between 3 and 300 K and in magnetic fields up to 10T.

Th-Po4-7
THz To Inspect Graphene And Thin Film Materials

Álvaro Cordón1; Luis Miranda1; Cristian Martínez1; Andrea Inés1; David Etayo1; Montserrat Fernández1; Pablo Rodríguez1; Elena Taboada1; Albert Redó-Sánchez1; Mónica Castrillo1; Miguel Laso2; Israel Arnedo1,2
1Das-Nano, Spain; 2Universitad Publica de Navarra, Spain

Th-Po4-8
Heteroepitaxy Of NLO Materials For Frequency Conversion Devices In The MWIR And LWIR With Applications In Defense And Security

Vladimir Tassev; Shivashankar Vangala
Air Force Research Laboratory, United States

While many materials used for frequency conversion in the midwave and longwave infrared (MWIR and LWIR) have achieved their fundamental limits, we propose heteroepitaxy as a solution. In this work a series of materials such as GaAs, GaP, ZnSe, GaSe, GaN and some of their ternaries have been grown with high surface and crystalline quality on non-native substrates and on non-native orientation-patterned templates using hydride vapor phase epitaxy. The grown thick device quality quasi-phase matching structures have been used for development of high power, compact, broadly tunable frequency conversion laser sources for the MWIR and LWIR with various applications in defense and security, including IR countermeasures, laser radar, high speed IR communications, remote sensing of chemical and biological agents, etc.

Th-Po4-9
Whispering-Gallery Resonators For Highly Integrated Plasmonic THz Circuits

Andreas Klein; Polina Stefanova; Michael Cooke; Claudio Balocco; Andrew Gallant
Durham University, United Kingdom

Whispering-gallery resonators based on spoof plasmonic rings are presented. The resonators exhibit exceptionally high quality factors for THz metasurfaces exceeding Q=65. As the resonator is coupled to two waveguides, it can serve as narrowband band-stop and band-pass filter in an integrated plasmonic circuit. The complicated mode structure shows frequency comb-like behaviour.

Th-Po4-10
High-Q THz Fano Metamaterial Interacting With Vacuum Electron

Dongpyo Hong1; Seontae Kim1; Matlabjon Sattorov2; Muhammad Mohsin Hossain1; Sun-Hong Min3; Gun-Sik Park1
1Seoul National University, Republic of Korea; 2Seoul-Teracom, Inc., Republic of Korea; 3Korea Institute of Radiological and Medical Sciences, Republic of Korea

By manipulating Fano resonance in metallic metamaterial, trapping and releasing of electromagnetic wave can be controlled. Simply, by varying the size of structural asymmetry to the proposed metallic slit structure, Q factor of trapped mode in metallic metamaterial can be tailored. We show that optimizing the electromagnetic property of Fano metamaterial can maximizes the interaction between convection electron and trapped mode, which gives significantly high efficiency of Cerenkov radiation larger than one from the ordinary Cerenkov and Smith-Purcell effects by order of two. We also observed inversion of the spectral asymmetry and the phase shift of high-Q trapped modes in subwavelength slits by manipulating the direction of the structural asymmetry of unit cell paving the way for full control of Fano resonances This finding is thought to be useful for many other potential applications other than Cerenkov lasing such as sensing and optical switching.

Th-Po4-11
THz Dielectric Photonic Crystal With Double Lattice

Mikhail Khodzitsky; Dainiel Gomon; Petr Demchenko
ITMO University, Russian Federation

nowadays there is a strong necessity of cheap and compact THz components for various THz applications. Photonic crystals (PC) are perspective candidate for this role. In this work we show ability to manipulate broadening of PC band gap by superposition of two different PC lattices.

Th-Po4-12
A Terahertz Metalattice: Single-layered Sub-wavelength Fibers

Shaghik Atakaramians1; Qigejian Wang2; Andrew Dempster2; Shahraam Afshar V.3
1UNSW Sydney, School of Electrical Engineering & Telecommunications, Australia; 2UNSW Sydney, School of EE&T, Australia; 3UniSA, School of Engineering,, Australia

We demonstrate a single layer of terahertz sub-wavelength fibers can act as an electromagnetic mirror due to the excitation of Mie-resonances and the lattice coupling. This opens up new avenues in developing simple terahertz metadevices for beam manipulation.

Th-Po4-13
Defect Mode For Periodic Structures With Broadband CPW-to-MS Transitions Fabricated With COC Polymer Substrate And On-wafer Measurements Up To 500GHz

Tahsin Akalin1; Abdallah Chahadih2; Ibrahim Türer3; Abbas Ghaddar2
1Lille University, France; 2Lebanese University, Faculty of Science, section V, Lebanon; 3Airbus Defence and Space, Germany

We present a broadband CPW-to-microstrip transition. The substrate is a 10µm-thin film of low loss COC polymer deposited by spin-coating on a locally metalized Silicon-wafer for the ground plane. In the microstrip section, we have fabricated a sinusoidally periodic pattern filter as a reference. In a second structure, we have included a defect in the middle of the filter. We have characterized both structures with on-wafer measurements up to 500GHz. The defect mode is clearly observed in the bandap with a nice peak at 290GHz.

Th-Po4-14
Terahertz Radiation Confinement Using Metallic Resonators

Théo Hannotte; Mélanie Lavancier; Sergey Mitryukovskiy; Jean-François Lampin; Romain Peretti
IEMN CNRS/Université de Lille, France

We designed, fabricated and characterized a microresonator in the terahertz range to increase light matter interaction using near-field optics. The goal of our device is to confine a THz electric field in a volume smaller than the diffraction limit. We aim at field confinement on a length scale of a few tens of nanometers

Th-Po4-15
Dynamic Controlling Of The Surface Magnetic Field Based On The VO2 Spiral Meta-surface

Xiaolin Hao1; Yaxin Zhang1; Qiwu Shi2; Shixiong Liang3
1University of Electronic Science and Technology of China, China; 2Si Chuan University, China; 3Hebei Semiconductor Research Institute, China

In this paper, we present a structure of meta-surface based on VO2 in terahertz band, which can use the laser to control the state of VO2, realizing the large change of surface magnetic field. As a phase change material, VO2 can be converted into the metallic state and the insulated state. This meta-surface can achieve the enhancement of surface magnetic field of up to 124.48 times in the metallic state of VO2 compared with the incident field. The surface magnetic field of meta-surface is achieved dynamic control and the ratio of magnetic flux density is 79 times in two states at 0.238 THz.

Th-Po4-16
Terahertz Smith-Purcell Effect In Photonic Crystals

Xiaoqiuyan Zhang; Min Hu; zhenhua wu; sen gong; tao zhao; diwei liu; renbin zhong; shenggang liu
University of Electronic Science and Technology of China, China

Free electrons passing along the surface of the grating produce a stimulated emission referred to as the Smith-Purcell (SP) effect. Here we firstly reveal theoretically evidence of the inverse Smith-Purcell effect (ISP) around 300GHz by loading the specially designed photonic crystals (PCs) with negative refractive on a slits structure. It could provide a new idea for coherent Smith-Purcell radiation source. Now we are working on the confirmatory experiment of the ISP around 20GHz. The proposal of ISP is of great significance for obtaining power enhanced, coherent and tunable terahertz radiation.

Th-Po4-17
Wire-grid Terahertz Metamaterial With Refractive Index Less Than Unity

Egor Litvinov; Petr Demchenko; Elizaveta Sheklanova; Mikhail Khodzitsky
ITMO University, Russian Federation

The research showed the possibility of designing materials with refractive index less than unity for terahertz frequency range using wire grid polarizer with specific geometric parameters. Specific refractive index can be obtained by simply rotating angle of polarization of the incident beam. It was shown also that this material can be simply made from metallized PET substrate using laser ablation.

Th-Po4-18
Terahertz Metamaterials Based On Free-standing Complementary Split Ring Resonators For Sensing Applications

Fatima Taleb1; Ibraheem Al-Naib2; Martin Koch1
1Philipps University Marburg, Germany; 2Imam Abdulrahman Bin Faisal University, Saudi Arabia

A highly sensitive metamaterial device has been designed based on free-standing complementary split ring resonators at terahertz (THz) frequencies. A thin-film overlayer deposited on the surface of the metal causes a red-shift in the resonant frequency of the THz transmission response. The results show the potential of such a device due to a high level of THz-overlayer analyte interaction that leads to a high-level sensitivity even with quite thin samples

Th-Po4-19
Electric Dipole-free Meta-cylinders

Mahdi Safari1; Ali Momeni2; Ali Abdolali2; Nazir P. Kherani1
1Department of Electrical and Computer Engineering, University of Toronto, Canada; 2Department of Electrical Engineering, Iran University of Science and Technology, Iran

Th-Po4-20
Fano Line Shapes Created In Metamaterials By Integrating Different Modes Of The Same Symmetry In Composite Structures

Rongyang Xu; Andreas Wieck; Nathan Jukam
Ruhr-University Bochum, Germany

Fano resonances are produced by integrating an electric split ring resonator (eSRR) and an I shaped resonator (ISR) into a composite metasurface. By adjusting the length of the ISR the degree of asymmetry in the line shape can be controlled and even made to be symmetric. Metasurfaces of the composite structures are fabricated, and their transmission is measured with terahertz time-domain spectroscopy. The measurements show good agreement with finite difference time domain (FDTD) simulations.

Th-Po4-21
Electromagnetic Responses And Coupling Effect In Asymmetric Terahertz Metamaterials

Qingli Zhou; Zhenwei Zhang; Jian Zuo; Chenyu Li; Zhou Yang; Lan Shi; Cunlin Zhang
Capital Normal University, Physics Dept., China

We experimentally and numerically demonstrate resonant behaviors of terahertz metamaterials can be tuned significantly by their asymmetry. In the asymmetric U-shaped structure, when terahertz electric-field is perpendicular to bottom bar, an interesting phenomenon comes up with three dips, which differs from the split-ring resonator which only has one dip in the transmission spectrum. By altering the position of the intermediate wire added in the asymmetric U-shaped structure, we could achieve and modulate resonant behaviors of the asymmetric samples, showing strong dependence on the polarization of the terahertz E-field. For the asymmetrically-cut double-ring structures, the mutual coupling between four arcs results in multi-resonance dips, especially a low-frequency Fano-like resonance accompanied with a sharp peak. Our asymmetric structures could offer potential applications in terahertz frequency selectors and bio-sensors.

Th-Po4-22
Terahertz Dielectric Constant Of Cell Wall Composition For Different Types Of Microorganisms

Sung-Ho Cha; Seung-Won Jun; Sae Ana Yoon; Yeong-Hwan Ahn
Ajou University, Republic of Korea

We investigated the THz dielectric constant of a wide range of microbial species in conjunction with their cell wall compositions. In general, the dielectric constant of the molds was lower than that of bacteria, whereas the yeasts exhibited particularly high dielectric constants, which were higher than that of water. The measurement on the dielectric constants of peptidoglycan and polysaccharides such as chitin, α-glucan, and β-glucans revealed that cell wall composition is the main cause of the observed differences in dielectric constants for different types of microorganisms.

Th-Po4-23
Metamaterials Sensor Based On Multiband Terahertz Absorber

Lihua Ma; Zijian Cui; Dongying Zhu; Lisha Yue; Lei Hou; Yue Wang
XI'an University of Technology, China

Metamaterials-based terahertz (THz) sensor becomes increasingly important with the growing development of THz functional devices. We experimentally demonstrate a metamaterials-based multiband absorber at f = 0.58, 0.92, and 1.58 THz. Utilizing the perfect absorption of an improved electric split resonant array, we were able to detect varying concentrations of the pesticides by reflection terahertz time-domain spectroscopy. The lowest detectable concentration that could be monitored was 0.1 mg/L. This sensing strategy based on metamaterials absorbers offers great potential to maintain the performance of reflection sensor even in nonlaboratory environments because of its sensitivity.

Th-Po4-24
Polarization Controlled Discrete Frequency-tunable Terahertz Absorber
Zijian Cui; Dongying Zhu; Lisha Yue; Cheng Ma; Yue Wang
XI'an University of Technology, China

A tunable absorber for the terahertz region is proposed which controlled by turning the polarization angle of incident excitation. Experiment and simulation results prove that the frequency corresponding to the absorption peak depends strongly on the angle of polarization.

Th-Po4-25
Multi-layered Graphene Based Optically Tunable Terahertz Absorber

Alexander Grebenchukov1; Anton Zaitsev1; Mikhail Novoselov1; Evgeniya Kovalska2; Anna Baldycheva2; Mikhail Khodzitsky1
1ITMO University, Russian Federation; 2University of Exeter, United Kingdom

We present a broadband tunable terahertz (THz) absorber, which consist of cross-shaped multi-layered graphene resonators. The proposed absorber possesses almost perfect absorption over the range 0.4-0.8 THz and can be easily fabricated. Dynamical tuning of absorption band is achieved by external optical pumping of modest intensity. This multi-layered graphene based absorber has high potential for various THz applications

Th-Po4-26
Active Control Of Terahertz Waves By VO2 Metamaterial

Caihong Zhang; Gaochao Zhou; Jingbo Wu; Biaobing Jin; Jian Chen; Peiheng Wu
Research Institute of Superconductor Electronics, Nanjing University, China

In this paper, we studied the mode switch and active control of THz waves from VO2 based THz metamaterials.

Th-Po4-27
Terahertz Near-field Metasurfaces And Superfocusing

Feng-Yuan Han; Li-Zheng Yin; Pu-Kun Liu
Peking University, China

In this work, a near-field metasurface is designed to overcome diffraction limit and superfocus terahertz waves by elaborately arranging the proposed unit cells with super small electric sizes. The full width at half-maximum beam width reaches up to 0.067λ0 (free-space wavelength) at a distance of 0.073λ0 at 0.437 THz. The near-field metasurface is beneficial for subwavelength resolution imaging, photolithography, non-contact sensing, and other applications in the near field.

Th-Po4-28
High-Speed THz Imaging For Production Line Monitoring

Lucy Downes; Andrew MacKellar; Charles Adams; Kevin Weatherill
Durham University, United Kingdom

We present a novel high-speed THz imaging technique and demonstrate its application in food production line monitoring. This new technique uses laser excited atoms to perform THz-to-optical conversion with the resulting light captured on an optical camera. Dried foodstuffs are imaged within their packaging and defects or contaminants identified. The presented system enables images to be taken at kHz rates, giving it the potential for use in high-volume production environments.

Th-Po4-29
A Suspended Silicon Terahertz Platform With Low Loss Waveguide And High Q Photonic Crystal Cavities

Elias Akiki1; Mattias Verstuyft2; Guillaume Ducournau1; Benjamin Walter3; Estelle Mairiaux3; Marc Faucher1; Jean-François Lampin1; Bart Kuyken2; Mathias Vanwolleghem1
1IEMN, CNRS UMR 8520, France; 2Ghent University-imec, Belgium; 3Vmicro SAS, France

A high Q optical resonator with a Q of 2700 and low loss terahertz Silicon waveguides with a loss below 0.8 dB/cm are fabricated and measured. Such a platform could form the basis for a low power photoacoustic terahertz gas sensor presented in our previous work.

Th-Po4-30
THz Thickness Characterization Of Polycarbonate Sheets Including Dispersion

Min Zhai; David Citrin; Alexandre Locquet
Georgia tech Lorraine, France

Terahertz (THz) time-domain spectroscopy (THz-TDS) has been attracted numerous attention due to its ability to investigate at depth in a nondestructive fashion many nonconductive materials. In this project, THz-TDS as well as advanced signal processing have been applied to characterize the thickness of polycarbonate sheets. We successfully characterize sheet thickness as well as obtain a quantitative measure of dispersion, i.e., the frequency-dependent refractive index.

Th-Po4-31
Iterative Tree Algorithm For The Assessment Of Optical Path Contributions Within Stratified Structures

Quentin Cassar; Adrien Chopard; Frédéric Fauquet; Jean-Paul Guillet; Mingming Pan; Jean-Baptiste Perraud; Patrick Mounaix
Laboratoire IMS / Université de Bordeaux / CNRS UMR 5218, France

The knowledge of the main optical paths contributing to the signal within stratified structures is unknown and non-intuitive. However, it would deepen THz-probing possibilities and improve property extraction processes. In this work, an iterative algorithm implements a connected propagation tree where each node denotes a subsequent pulse subdivision inside a layered material. Each propagating pulse is individually monitored and its carried proportion of the incident power remains at any time accessible. The main optical routes contributing to the signal recorded from an aeronautic stack are identified. A parametric transfer function is derived, reducing by 98.2% the number of calculations to recover the experimental signal shape

Th-Po4-32
Application Of Hydrogen-bonded Liquid Crystal Device To THz Phase Sensing

Ryota Ito; Michinori Honma; Toshiaki Nose
Akita Prefectural University, Japan

We investigated a phase shifting interferometry which was based on four-step phase-shifting algorithm by using liquid crystal (LC) phase shifter in THz region. In this study, we introduce a hydrogen-bonded LC, which shows almost no dichroism at 2.5 THz. The phase shifting interferometry is investigated by using an optically pumped gas laser system which can generate continuous wave (CW) THz waves. Since hydrogen-bonded LC shows almost no dichroism at 2.5 THz, we successfully demonstrated precise measurement of the birefringence of X-cut crystalline quartz. We believe that introducing the hydrogen-bonded LC phase shifter into the THz phase sensing is promising method.

Th-Po4-33
Two Channel Terahertz Communication Based On Spatial Mode Multiplexing

Yulia Choporova1; Boris Knyazev1; Vladimir Pavelyev2; Natalia Osintseva1; Konstantin Tukmakov2
1Budker institute of nuclear physics, Russian Federation; 2Samara University, Russian Federation

Mode spatial multiplexing has been shown for Gauss-Hermite and vortex beams in the THz spectral range. Transformation of a Gaussian TEM00 input beam of Novosibirsk Free Electron Laser was realized by silicon diffractive optical elements. Superposition of vortices with different topological charges has been examined A correlation filter was applied for mode analysis.

Th-Po4-34
High Resolution Image Processing Technique For The Detection Of Metal Entrapments Based On A THz Camera

Benedikt Friederich; Dilyan Damyanov; Jessica Kohl; Kevin Kolpatzeck; Xuan Liu; Thorsten Schultze; Andreas Czylwik; Jan Balzer; Ingolf Willms
University of Duisburg-Essen, Germany

In this paper, we introduce a promising high resolution multistage approach for THz cameras for the detection and curvature extraction of metal fragments. The capability of this technique is demonstrated by detecting a 4 mm ÃfÆ'Ã?â?TÃf¢ââ?s¬" 7 mm large metal fragment placed on a plank of beechwood.

Th-Po4-35
Investigating Liquid Water Distribution In Nafion Polymer Electrolyte Membrane With Terahertz Imaging

Decio Alves de Lima; Rosa Letizia; Riccardo Degl'Innocenti; Richard Dawson; Hungyen Lin
Lancaster University, United Kingdom

Nafion® polymeric membranes are the most common electrolyte material for proton exchange membrane fuel cells (PEMFC), requiring adequate hydration in order to reach high proton conductivity. The relatively high attenuation of terahertz (THz) radiation of liquid water enables a contrast to be observed for inspecting water build-up in Nafion® membranes. This paper investigates the feasibility of a compact THz system using a THz camera for liquid water imaging and quantification in a Nafion® polymeric membrane

Th-Po4-36
Terahertz Polarimetric Sensing For Linear Encoder Based On A Resonant-Tunneling-Diode And CFRP Polarizing Plates

Genki Yamashita1; Wataru Tsujita1; Hiroyuki Tsutada1; Rui Ma2; Pu Wang2; Philip Orlik2; Safumi Suzuki3; Adrian Dobroiu3; Masahiro Asada3
1Mitsubishi Electric Corporation, Japan; 2Mitsubishi Electric Research Laboratories, United States; 3Tokyo Institute of Technology, Japan

We report the first experimental results on the linear encoder based on a resonant-tunneling-diode (RTD) and a periodic linear array of carbon fiber reinforced plastic (CFRP) plates as a scale. By using polarization dependent reflection signal, we were able to detect the incremental position.

Th-Po4-37
Beyond Fusion: The Application Of Fusion-Based Microwave Technology To Other Industries

James Anderson; John Doane; Howard Grunloh; Michael Brookman
General Atomics, United States

Technology developed in the pursuit of fusion energy has had an impact in many other industries. The requirements being met by advanced microwave and millimeter wave components for fusion applications can open up whole new areas in emerging industries. For plasma heating, microwave components such as waveguide, switches, and polarizers, are being built which can withstand megawatts of sustained power at frequencies up to 170 GHz. In microwave-based diagnostics for fusion systems, enormous frequency bandwidths such as 35-170 GHz are possible for transmission lines at very high propagation efficiency (< 1% loss over 100 m). The techniques and materials being developed for these systems are transferrable to other microwave-based applications.

Th-Po4-38
Difficulties Of Subsurface Liquid Front Tracking In Porous Media With Terahertz Pulsed Imaging

Mohammed Al-Sharabi1; Theona Mudley1; Daniel Markl2; Prince Bawuah1; Anssi-Pekka Karttunen3; Cathy Ridgway4; Patrick Gane5; Jarkko Ketolainen3; Kai-Erik Peiponen6; Thomas Rades7; Axel Zeitler1
1University of Cambridge, Department of Chemical Engineering, and Biotechnology, United Kingdom; 2University of Strathclyde, Institute of Pharmacy, and Biomedical Sciences, United Kingdom; 3University of Eastern Finland, School of Pharmacy, Finland; 4Omya International AG, Switzerland; 5Aalto University, Department of Bioproducts and Biosystems, Finland; 6University of Eastern Finland, Institute of Photonics, Finland; 7University of Copenhagen, Department of Pharmacy, Denmark

Terahertz pulsed imaging (TPI) coupled with a customised flow cell has previously been used successfully to study liquid transport in porous media, such as powder compacts. In some samples, the tracking of the liquid front remains challenging when the refractive indices of liquid and sample are similar and hence little contrast is observed. In this work, we found that even when the relative difference between the refractive indices of liquid and sample is high, it can still be challenging to track the reflection peak of water in some samples while it works fine in others. It is hypothesised that this is due to the formation of a water gradient in these samples due to their specific microstructure and we explore methods to overcome this limitation.

Th-Po4-39
Hexagonal Polygon Mirror Based Terahertz Imaging System by Using Telecentric F-θ Lens

Mugeon Kim; Eui Su Lee; Dong Woo Park; IL-Min Lee; Kyung Hyun Park
Electronics and Telecommunications Research Institute, Electronics and
Telecommunications Research Institute, Republic of Korea

In this paper, we propose a high-speed terahertz(THz) imaging system by using a hexagonal polygon mirror. The system consists of a single emitter, detector, a hexagonal polygon mirror for scanning, and a telecentric f-θ lens for imaging. The THz wave from the emitter is two-dimensionally steered by a polygon mirror and irradiated to the object through a telecentric f-θ lens. The irradiated THz wave is reflected by the object and then returns to the detector in the same path as the optical path illuminated by the telecentric f-θ lens. In this process, when the THz wave goes out of the lens, the clock mirror extracts the clock signal for the image alignment processing.

Th-Po4-40
Influence Of Bandwidth And Dynamic Range On Thickness Determination Using Terahertz Time-domain Spectroscopy

Lukas Liebelt
1; Stefan Weber2; Jens Klier2; Tobias Pfeiffer2; Daniel Molter2; Frank Ellrich1; Georg von Freymann2
1University of Applied Sciences,, Germany; 2Fraunhofer ITWM, Germany

Terahertz time-domain spectroscopy (TDS) is a very attractive technique in the field of nondestructive layer-thickness determination. The characteristics of the generated terahertz pulses -- bandwidth and dynamic range -- have direct influence on the thickness-determination performance. The resulting effects are investigated in this contribution

Th-Po4-41
Terahertz Near-field Inspection For High-resolution Conductivity And Mobility Mapping Of Large-area Graphene

Alexander Michalski; Simon Sawallich; Michael Nagel
Protemics GmbH, Germany

We present contact-free Terahertz (THz) near-field measurements suitable for inspection of large-area graphene. From THz transmission measurements, charge carrier properties in graphene are deduced. By using high-resolution near-field detectors conductivity variations on a 10um scale can be observed. Full spectral analysis enables the calculation of carrier mobilities, reaching up to 5000 cm^2/Vs for the samples under test.

Th-Po4-42
Identification Of Random Internal Structuring THz Tags Using Images Correlation And SIWPD Analysis

Florent Bonnefoy1; Cornel Ioana2; Maxime Bernier1; Nicolas Barbot3; Romain Siragusa3; Etienne Perret3; Philippe Martinez4; Frédéric Garet1
1University of Savoie Mont Blanc, Laboratory IMEP-LAHC, France; 2University Grenoble Alpes, GIPSALAB laboratory, France; 3University of Grenoble Alpes, LCIS, France; 4Centre Technique du Papier, France

In this work, we propose a THz tag structure based on a stack of different dielectric layers made of PE and PE-TiO2 mixture, in which we voluntary randomly deposit metallic flakes. Due to the randomness of the flake distribution (position and size), such a structure exhibits a potential unique THz signature that could be used to address identification using targeted statistical analysis via the 2D correlation coefficient and a SIWPD analysis. The signature is obtained by making a 2D THz image of a given area of the structure.

Th-Po4-43
Study On The Terahertz Vortex Imaging Based On Spiral Phase Plates

Hui Liu1; Kun Yan1; Shiyou Wu2; Chao Li2; Chao Chang2; Guangyou Fang2
1University of Chinese Academy of Sciences, China; 2Institute of Electronics, Chinese Academy of Sciences, China

A novel terahertz (THz) imaging method based on vortex wave is presented. First, the analytical expression of field distribution of the THz vortex beam generated by spiral phase plate (SPP) is derived, and the propagation characteristics of vortex beams with different topological charges are analyzed. Subsequently, the THz vortex imaging model is established, and fast Fourier transform (FFT) is used to reconstruct the target's azimuthal image. Simulation results demonstrate that vortex beam has the prospect for acquiring the azimuthal information of target. The work can also promote the development of the novel THz imaging technology.

Th-Po4-44
Quasi-Optical Dielectric Lens Design For D-Band Passive Millimeter-Wave Imager
Yan YOU1; ZiRan Zhao2; Xuming Ma1
1Nuctech Company Limited, P.R. China; 2Department of Engineering Physics, Tsinghua University, P.R. China

The main characteristics of passive millimeter wave imaging imaging system, including the field of view (FOV), the spatial resolution (SR) and the thermal sensitivity are mainly decided by the quasi-optical lens. The angle scanning ability of the lens decides the FOV of the system, and the beam spot size formed by lens decides the SR of the system, and the efficiency of the lens affects greatly the thermal sensitivity of the system. To achieve the low aberration loss, many authors have demonstrated their usage of aspheric lens. However, the high-order terms of the aspheric surface always leads to fabrication difficulty. In this paper, we demonstrate that there is no need to use aspheric surfaces to obtain a diffraction-limited beam. The surfaces of the lens is optimized by Zemax software. Diffraction limited beam with a beam spot of 3 dB width about 15 mm and a FOV of 884mm.

Th-Po4-45
Portable Terahertz Radar For Rapid Long-range Detecting Concealed Carried Threat

Ziru Sang1; Yujiao Zhao2
1Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, China; 2the University of Hong Kong, Hong Kong

Rapidly discriminating potential threat in crowd scenarios from a long distance at an early stage is significant to avoid damage to public. Utilizing depolarization effect of different targets, a portable 0.14THz radar prototype is developed to detect the concealed body-worn weapons. This paper illustrates the schematic of system and proposes a fast algorithm to verify the performance. The prototype used a linear frequency modulated continuous wave (FMCW) waveform with a sweep range from 134.4GHz to 138.4GHz and the sweep pulse width of 100us. The signal is transmitted by one horizontal antenna and received by two antennas one of which is horizontal polarization and the other is vertical. The experiments results show that the developed prototype can detect metal gun and improvised explosive devices successfully. The performance can be further improved by tuning detection parameters and increasing antenna aperture.

Th-Po4-46
Investigation Of Terahertz Characterization Of Nitrocellulose

Mohamed LAZOUL; Noureddine MAAMAR; Boufateh BEZZIOU
Ecole Militaire Polytechnique, Algeria

The aim behind this work is to achieve a terahertz characterization of a highly flammable and explosive materials such as nitrocellulose that can be easily synthesized and implemented in improvised explosive device. It is highly desirable to detect and accurately identify them, especially when they are mixed or concealed by other ordinary and harmless products. Many of these materials, especially the organic ones, exhibit unique fingerprints in the THz range due to inter- or intra-molecular vibrations of the whole molecules. From the recorded fingerprints, detection through THz imaging or identification of the chemicals is possible. Terahertz time-domain spectroscopy measurements in transmission and reflection modes are carried-out to fully identify the material ever when concealed by other materials.

Th-Po4-47
Practical Guidelines For Continuous Wave Terahertz Spectroscopy — Perspectives And Challenges In Stand-off Detection

Pawel Cielecki; Mathias Hedegaard Kristensen; Esben Skovsen
Aalborg University, Denmark

In this paper, we discuss practical aspects of continuous wave frequency-domain terahertz spectroscopy measurements. We highlight benefits of using various detection schemes and system configurations. The presented paper constitutes a guideline to continuous wave terahertz spectroscopy with a special emphasis on stand-off measurements.

Th-Po4-48
Terahertz 3D Water Distribution In Plant Leaves

Abhishek K Singh
1; Arely Viridiana Perez-Lopez2; June Kilpatrick Simpson-Williamson2; Enrique Castro-Camus1
1Centro de Investigaciones en Optica, Mexico; 2Cinvestav Unidad Irapuato, Mexico

The estimation of hydration level in plant tissues is a fundamental parameter for plant scientists. The Terahertz spectroscopy provides a non-destructive methods to estimate the water content in plant tissues with good precision in contrast to the conventional method involving comparison of the fresh and dry weight of leaves. Recently, terahertz spectroscopy was employed to estimate the hydration level of plant leaves. However, most of the previous measurements were concerned about water level and drought stress behavior via measurements at specific chosen point only. Yet, a few two dimensional images have been reported. Here we present a 3D distribution of water in Agave victoria reginae leaves employing terahertz time-domain imaging spectroscopy.

Th-Po4-49
Physical Properties Of Human Jawbone, Spongy Bone, Collagen And Cerabone® Bone Transplantation Material In Range Of 0.2 To 2.5 THz

Anahit Nikoghosyan1; Jingling Shen2; He Ting2
1Yerevan State University, Armenia; 2Capital Normal University, China

The physical properties of human jawbone, spongy bone, collagen and the human bone substitute CeraboneÃfÆ'Ã?â?TÃf¢ââ?s¬Ã.¡ÃfÆ'ââ,¬Å¡Ãfâ?sÃ,® have been investigated using terahertz (THz) time-domain spectroscopy (TDS). The refractive indices n(?) and linear absorption coefficients ?(?) of bone tissue and transplantation material have been determined within the range of the spectrum between 0.2 THz and 2.5 THz. The obtained results allow us to determine the proximity of the physical properties of the CeraboneÃfÆ'Ã?â?TÃf¢ââ?s¬Ã.¡ÃfÆ'ââ,¬Å¡Ãfâ?sÃ,® bone transplantation material with the natural bone matrix.

Th-Po4-50
Collective Hydration Dynamics In Binary Mixtures: A THz Time Domain Spectroscopic Study

Debasish Das Mahanta; Animesh Patra; Nirnay Samanta; Rajib Mitra
S. N. Bose National Centre for Basic Sciences, India

We have studied the structure and dynamics of water in its binary mixture with two amphiphilic molecules 1,2-dimethoxy ethane (DME) and dimethyl sulfoxide (DMSO) by THz time domain spectroscopy (TTDS) (0.3-1.6 THz region). In both the cases a non-ideal behavior of the mixture is found owing to the formation of water clusters. The cooperative dynamics of water obtained from Debye relaxation of TTDS data reveals a non-monotonous behavior as a function of water concentration (Xw).

Th-Po4-51
Non-invasive And Non-destructive Approach Based Infrared Thermography To Estimate Thermal Properties In Vivo

Fernando Malheiros
1; Alisson Figueiredo2; Luis Henrique Ignacio3; Neumar Malheiros4; Henrique Fernandes5
1Minas Gerais State University, Brazil; 2Federal University of Ouro Preto, Brazil; 3Goiano Federal Institute, Brazil; 4Federal University of Lavras, Brazil; 5Federal University of Uberlandia, Brazil

Estimation of thermal properties in vivo tissue is important to predict and control biological procedures, since they are dependent of temperature behavior. However, in vivo estimation of human thermal properties in a non-invasive and non-damage manner is a challenging task. In this paper, we propose an approach to estimate thermal properties in vivo. The approach is non-invasive and non-damage since it uses only external measurements. Considering the experimental results, the non-invasive procedure using heat flux and temperature variation is a feasible tool to estimate thermal properties in in vivo.

Th-Po4-52
Effect Of Confinement On Collective Dynamics Of Nanoconfined Water In DMPC Multilamellar Vesicle

Jeongmin Jang; Kihoon Eom; Sunmyeong Kim; Gun-Sik Park
Seoul National University, Republic of Korea

In this work, when PEG-induced reduction was made in interlamellar spacing of DMPC-MLV, the collective reorientational dynamics of the water beyond the hydration layer was observed to be accelerated regardless of the interlamellar spacing compared with that of bulk water. With PEG-induced narrower spacing, however, the acceleration becomes slower and converges with a characteristic distance.

Th-Po4-53
In Vivo Terahertz Imaging For Scar Treatment Evaluation

Jiarui Wang1; Qiushuo Sun1; Rayko I. Stantchev1; Emma Pickwell- MacPherson2
1The department of Electronic Engineering, The Chinese University of Hong Kong, China; 2Department of Physics, The University of Warwick, United Kingdom

We use THz imaging to measure and quantify the effects of applying silicone gel sheeting on skin. We show how THz measurements can detect subtle hydration changes caused by the silicone gel sheeting, indicating that THz imaging is a promising method to quantitatively assess skin treatment strategies.

Th-Po4-54
Terahertz Spectroscopic Identification Of Different Species Of Herbal Medicine Fritillaria

Jun Zhou1; Lin Zhou1; Yanshun Zheng1; Zheng Zhu1; Xinmei Xu2; Guihua Jiang2
1University of Electronic Science and Technology of China, China; 2Chengdu University of Traditional Chinese Medicine, China

In this work, herbal medicine samples of different species of Fritillaria were measured by terahertz time-domain spectroscopy and analyzed by the projection method and the LargeVis algorithm. The results show that the experiment method combined with the advanced algorithm used in this paper can get a better visualization compared to principal component analysis. This technology can be used to qualitatively identify similar herbal medicines.

Th-Po4-55
Highly Sensitive Terahertz Imaging Method For Paraffin Embedded Cancer Samples

Kai Liu1; Qiushuo Sun1; Xuequan Chen1; Arturo Hernandez-Serrano2; Emma Pickwell-MacPherson2
1the Chinese University of Hong Kong, Hong Kong; 2Department of Physics, University of Warwick, United Kingdom

Differentiating thin film cancer tissue from normal tissue with terahertz (THz) light has been investigated for decades, primarily with breast cancer samples. However research is seldom done on thin film oral cancer tissue, and this typically has low contrast compared with normal tissue in ordinary THz geometries. In this paper, we demonstrate how a window-sample-water sandwich structure can significantly enhance the contrast in reflection geometry terahertz time domain spectroscopy. Our method is highly sensitive compared to traditional THz transmission or reflection imaging. We image paraffin-embedded oral cancer tissues to show how the proposed method increases the sensitivity for solid low-absorptive thin film cancer samples by over a factor of 5.

Th-Po4-56
Study Of Protein Water Interactions In GroEL Molecular Chaperonins Using Terahertz Spectroscopy

Nirmala Devi1; Anwar Sadat2; Shaumik Ray1; Kausik Chakraborty2; Koyeli Mapa3; Bala Pesala1
1CSIR-Central Electronics Engineering Research Institute, India; 2CSIR-Institute of Genomics and Integrative Biology, India; 3School of Natural Sciences, Shiv Nadar University, India

THz spectroscopy is an attractive technique to study the interaction of proteins in water as it is highly sensitive to water mediated interactions. GroEL, a barrel shaped chaperonin known for assisting protein folding, is studied using THz-TDS technique for varying concentrations. Results show significant decrease in absorption with increasing concentrations demonstrating the formation of more bound water due to the presence of GroEL complex.

Th-Po4-57
Reconstructed THz Phase Image Of The Two-component Numerical Model Of Breast Cancer Tissue

Olga Smolyanskaya1; Maksim Kulya1; Quentin Cassar2; Olga Kravtsenuk1; Patrick Mounaix2; Jean-Paul Gullet2; Kirill Zaytsev3; Nickolay Petrov1
1ITMO University, Russian Federation; 2Bordeaux University, France; 3Bauman Moscow State Technical University, Russian Federation

The angular spectrum method can be applied for the analysis of light diffraction on thin films. In model we have used the Debye coefficients instead of complex dielectric permittivity that making our calculations more rapid. In this work, we have conducted a simulation of the image reconstruction of histological slides, consisting of normal and cancer tissue.

Th-Po4-57
Reconstructed THz Phase Image Of The Two-component Numerical Model Of Breast Cancer Tissue
Olga Smolyanskaya1; Maksim Kulya1; Quentin Cassar2; Olga Kravtsenuk1; Patrick
Mounaix2; Jean-Paul Gullet2; Kirill Zaytsev3; Nickolay Petrov1
1ITMO University, Russian Federation; 2Bordeaux University, France; 3Bauman Moscow State
Technical University, Russian Federation

Th-Po4-58
Signal Denoising Algorithm For Terahertz Imaging And Spectroscopy

Xuequan Chen; Emma Pickwell-MacPherson
The Chinese University of Hong Kong, China

One important downfall of terahertz time-domain spectroscopy is the slow data acquisition rate by the point-by-point sampling. In many cases requiring a fast measurement such as raster-scan imaging, the signal-to-noise ratio is usually bad due to the very short integration time. We propose a denoising algorithm that efficiently reduces the noise from the system and/or water-vapour absorptions. Experimental results demonstrate a significantly improved accuracy and reduced standard deviation.

Th-Po4-59
Angular Distortion Removal Of THz Anisotropic Dichroism Microscope

Yanting Deng; Katherine Niessen; Andrea Markelz
State University of New York-Buffalo, United States

We have developed a stationary sample THz anisotropic dichroism microscope as a powerful tool for material characterization. The key innovation is the use of an iso-response curve defined by the terahertz and detection light polarizations. Here we show that following a continuous iso-response curve introduces angular distortion in the spectrum, and this distortion can be eliminated by using a discontinuous iso-response angle pairs avoiding large gradient regions. Employing this additional constraint on the relative polarizations provides a convenient technique for rapid anisotropic terahertz spectroscopy.

Th-Po4-60
Collective Oscillations Of Proteins Proven By Terahertz Spectroscopy In Aqueous Medium

Yoann Meriguet1; Mathias Lechelon2; Matteo Gori2; Ilaria Nardecchia2; Frederic Teppe3; Anastasiia Kudashova1; Dominique Coquillat3; Luca Varani1; Marco Pettini2; Jeremie Torres1
1Institut d'Electronique et des Systèmes (IES), France; 2Centre de Physique Théorique (CPT), France; 3Laboratoire Charles Coulomb (L2C), France

Understanding the forces that enable protein interactions is a major scientific challenge. Indeed, Brownian diffusion alone, which is usually considered as the main engine of protein dynamics, does not explain the rapidity and efficiency of the biomolecular reactions at works in cells. In this work we will present the first observation of the collective oscillations of a model protein driven out-of-equilibrium by means of optical excitation in aqueous medium using terahertz spectroscopy.

Th-Po4-61
IR And THz Imaging Of Paraffin Embedded Cancer Tissues

Yury Kistenev1; Alexey Borisov1; Viktor Nikolaev1; Denis Vrazhnov2; Anastasya Knyazkova1
1Tomsk State University, Russian Federation; 2Institute of Strength Physics and Materials Science of Siberian Branch of the RAS, Russian Federation

A gold standard of cancer diagnosis is expert evaluation of biopsy histological sections. The accuracy of classification depends on experimental data dimension, that can be increased using spectral information of the samples. An approach of computer-aided paraffin embedded cancer tissue samples analysis, using IR and THz imaging technique and machine learning, is discussed.

Th-Po4-62
First Experiments On Ion Bean Formation At GISMO Facility

Alexander Sidorov; Sergey Golubev; Ivan Izotov; Roman Lapin; Sergey Razin; Roman Shaposhnikov; Vadim Skalyga; Sergey Vybin; Alexey Bokhanov; Mikhail Kazakov; Sergey Shlepnev; Mikhail Glyavin; Alexander Tsvetkov; Mikhail Morozkin; Mikhail Proyavin; Ivan Plotnikov
Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS), Russian Federation

The present article demonstrates the recent results of investigations devoted to development of a new generation of a high-current ion sources and its application in a scheme of a neutron generator capable to generate neutron fluxes that surpass the state-of-the-art devices by an order of magnitude. The recent results at GISMO experimental facility on light and heavy ion beams production will be reported. Measurements results of an ion beam current, its emittance and charge state distribution will be presented.

Th-Po4-63
Electromagnetic Reflectance Measurements Of Human Palms In Sub-THz Frequency Band

Anna Kochnev1; Alexander Puzenko1; Paul Ben Ishai2; Yuri Feldman1
1The Hebrew University of Jerusalem, Israel; 2Ariel University, Israel

Electromagnetic (EM) reflectance measurements of human palms were made for 21 subjects in the frequency range of 426-432 GHz. This range is expected to lie in the vicinity of the axial mode of the coiled sweat ducts, which were triggered by varying levels of stress. The EM measurements were correlated to known indicators of stress and high levels of correlation were observed during mental stress. A paired Student's t-test also showed an intrinsic difference between the rest and mental stress sections. The observations are intriguing and require further inquiry.

Th-Po4-64
Terahertz Study Of Wood Structure As Impacted By Grapevine Trunk Diseases

Dominique Coquillat1; Yoann Meriguet2; Nina Dyakonova1; Christophe Consejo1; Petre Buzatu1; Jeremie Torres3; Luca Varani3; Julie Perry4; Romain Fernandez5; Samuel Merigeaud6; Jean-Luc Verdeil7; Maïda Cardoso1; Christophe Goze-Bac1; Anne-Sophie Spilmont8; Philippe Larignon9; Jean-Pierre Peros10; Loïc Le Cunff8; Cedric Moisy5
1Laboratoire Charles Coulomb (L2C), University of Montpellier, France; 2Laboratoire Charles Coulomb (L2C) , Institut d'Electronique et des Systèmes (IES), University of Montpellier, France; 3Institut d'Electronique et des Systèmes (IES), University of Montpellier, France; 4Comité Interprofessionnel du Vin Champagne, France; 5IFV - Pole Matériel Végétal, UMT Géno-Vigne, France; 6Tridilogy, France; 7CIRAD, UMR AGAP, Plateforme PHIV, France; 8IFV, Pôle Matériel Végétal, UMT Géno-Vigne, France; 9IFV, Pôle Rhône-Méditerranée, France; 10INRA, UMR AGAP, DAAV, UMT Géno-Vigne, France

This study has successfully demonstrated the use of THz time-domain imaging to identify the grapevine wood tissues degraded by the fungi responsible for grapevine trunk diseases.

Th-Po4-65
Sub-surface Analysis Of Ancient Human Remains Using A Robotic-based THz System

Eva-Maria Stuebling1; Arno Rehn1; Tabea Siebrecht1; Yannick Bauckhage2; Lena Oehrstroem3; Patrick Eppenberger3; Jan C. Balzer4; Frank Ruehli3; Martin Koch1
1Philipps-Universitaet Marburg, Germany; 2University Aaalen, Germany; 3University of Zurich, Switzerland; 4Universitaet Duisburg-Essen, Germany

We used THz time-domain imaging with a robotic-based THz system for a tomographic reconstruction of the sub-surface structure of an artificially mummified ancient Egyptian human left hand. A comparison between the THz tomography data and a conventional CT and a micro-CT scan reveals, that the depth resolution of the THz images exceeds the resolution of a conventional CT scan and is comparable with a micro-CT scan. Using such a robotic-based THz system promises new insights into the sub-surface structure of human remains.

Th-Po4-66
Is There A Water Content Threshold For Cluster Formation In Glycerol?

Johanna Kölbel; Axel Zeitler
University of Cambridge, Department of Chemical Engineering and Biotech., United Kingdom

The stability of freeze-dried formulations due to residual water is a topic of significant interest. Glycerol, a cryoprotectant that is widely used in freeze drying, is mixed with water in different concentrations and measured with terahertz time-domain spectroscopy over a wide range of temperatures. Here, the question of whether there is a threshold for water clustering or a gradual change in the relative amount of unclustered water upon increased water content is addressed. When plotting the absorption coefficient versus temperature, four distinct temperature regions are identified that are characteristic with the three relaxation regimes of disordered organic molecular materials with temperature. The onset temperature of molecular mobility can be extracted from the terahertz experimental data. Rather than a gradual change we find evidence from this data for a distinct threshold at a water concentration of 5 wt.%.

Th-Po4-67
Short-time Fourier Transform With Adaptive Window Sizing For THz-TDS

Jun Song1; Sebastian Engelbrecht2; bernd fischer2; Hungyen Lin3
1Nanjing Forestry University, China; 2French-German Research Institute of Saint-Louis, France; 3Department of Engineering, Lancaster University, United Kingdom

An adaptive windowing short-time Fourier transform algorithm is proposed where the width of short-time window is adaptively adjusted based on the frequencies of interest. The algorithm is then applied to lactose measurements acquired using THz-TDS and compared against the standard fixed window STFT spectrogram where improved contrast can be observed.

Th-Po4-68
Spectroscopic Characterization At THz Frequencies Of Glucose-based Biomaterials: Paramylon, Paramylon-ester And Cellulose
Junlan Zhong1; Tatsuya Mori2; Midori Yamashiro3; Takanari Kashiwagi2; Teruhiko Tanaka2; Hidehisa Kawashima2; Junko Ito4; Masashi Kijima2; Masatoshi Iji3; Makoto M. Watanabe2; Kazuo Kadowaki2
1Graduate School of Life and Environment Sciences, University of Tsukuba, Japan; 2University of Tsukuba, Japan; 3System Platform Research Laboratories NEC Corporation, Japan; 4ABES Center, University of Tsukuba, Japan

In this study, the THz absorption of paramylon, paramylon ester and cellulose were measured and analyzed. The spectra of cellulose and paramylon showed great difference with each other which may be caused by their different chain structures. By comparing the spectra of the paramylon and paramylon ester, we speculate that the broader absorption widths and the shifts in frequency of paramylon-ester are attributed to results of the long chain molecular interaction and the degree of disorder of the vibration modes. This result demonstrates that the THz spectroscopy is very useful for identifying the degree of disorder in polymeric materials. Further detailed study is needed to elucidate microscopic origin of the differences in THz absorption features in glucose-based biomaterials.

Th-Po4-69
Rapid Classification Of Bi-heterocyclic Compounds by Using THz-TDS With Combined Double-loop Learning SVM And KNN

Maciej Nowak1; Rafal Zdunek2; Kacper Nowak2; Marcin Jaroszewski1; Edward Plinski2; Piotr Swiatek1; Malgorzata Strzelecka1; Stanislawa Plinska1; Wieslaw Malinka1
1Wroclaw Medical University, Poland; 2Wroclaw University of Science and Technology, Poland

The presented concept of recognizing bi-heterocyclic compounds based on THz spectra allows us to clearly determine whether the tested sample is a known or maybe it is a new synthesized one. In addition to the use in medical chemistry, the method can also be used to fight counterfeit medicines and control the quality of medicines on the production line.

Th-Po4-70
Terahertz Response From Oligonucleotides Deposited On Silicon Nanostructures

Maksim Fomin1; Andrew Chernev2; Leonid Klyachkin2; Anna Malyarenko2; Nikolay Bagraev2
1Peter the Great St.Petersburg Polytechnic University (SPbPU), Russian Federation; 2Ioffe Institute, Russian Federation

It was shown that oligonucleotides can be identified by studying the change in the conductance and transverse potential difference of a SNS under conditions of their application on the SNS edge-channel region. From the value of the oscillation period of the longitudinal conductivity and the transverse potential difference ladder at Hall contacts, the magnitude of the frequency response of the DNA oligonucleotide deposited on the surface of a silicon nanosandwich is determined. The development of this technique can be used to determine various characteristics of DNA oligonucleotides, in particular, to identify their dielectric, magnetic and optical properties, that is important when the THz radiation sources are applied to for various purposes of personalized medicine, as well as for developing express diagnostics of DNA oligonucleotides

Th-Po4-71
Terahertz Imaging Of Moisturizer Interaction With The Skin In-vitro

Mariana Alfaro1; Daniela Ramos-Soto1; Abhishek Singh2; Edgar Saucedo-Casas1; Enrique Castro-Camus2
1Universidad Autonoma de Aguascalientes, Mexico; 2Centro de Investigaciones en Optica, Mexico

We use terahertz spectroscopic imaging to visualize skin-hydration processes of moisturizing agents (lanolin and glycerin) over stratum corneum in-vitro. The occlusive nature of lanolin as well as the hyper-osmotic hydration mechanism of glycerin were observed. Our THz results demonstrate that THz imaging is a potential tool for real time visualization of skin care products and their interaction with skin.

Th-Po4-72
How To Make Water Transparent For THz Radiation?

Maxim Nazarov1; Maria Konnikova2; Olga Cherkasova3; Alexander Shkurinov4
1Kurchatov institute, Ploshchad' Akademika Kurchatova, Russian Federation; 2Department of Physics and International Laser Center, Lomonosov Moscow State University, State University, Russian Federation; 3Institute of Laser Physics SB RAS, Russian Federation; 4Department of Physics and International Laser Center, Lomonosov Moscow State University, ILIT RAS - Branch of the FSRC «Crystallography an, Russian Federation

In a simple experiment we demonstrate that the transmission of a 100 ÃfÆ'Ã.½Ãfâ?sÃ,¼m water layer in the THz range can be increased by an order of magnitude. For that purpose it is necessary to bind all water, for example with a large amount of glucose. It is not possible in a liquid state, but can be realized in wet powders. This way we can extract bound water spectra without being constrained by free water dominating absorption.

Th-Po4-73
Differences And Similarities Between Millimetre Wave And Thermal Heating Effect On Action Potential Triggering In Leech Interneuron

Sergii Romanenko1; Peter Siegel2; Livia Hool1; Alan Harvey1; Vincent Wallace1
1Univ. of Western Australia, Australia; 2California Institute of Technology, United States

MMW radiation can be used to focally deposit energy into biological tissue, which converts in it into thermal energy due to high absorption properties, specifically of water. As a result, it can affect the functionality of some biological tissues. Neuronal tissue is one of the most susceptible types due to its high sensitivity to environmental changes, such as electric field and temperature. Here we investigate the effect of MMW mediated heating and conventional thermal heating on action potential voltage initiation in spontaneously active interneuron of leech. The results demonstrate that MMW radiation has a different effect to thermal heating but only at initial stages of sample heating.

Th-Po4-74
Utilisation Of MMW Radiation To Facilitate Apoptosis In Triple Negative Breast Cancer Cell Lines Via TRPV1 Receptor Sensitization

Anabel Sorolla1; Sergii Romanenko2; Peter Siegel3; Vincent Wallace2
1Harry Perkins Institute of Medical Research, Australia; 2Univ. of Western Australia, Australia; 3California Institute of Technology, United States

Triple-negative breast cancers (TNBC) are highly aggressive malignancies comprising ~15-20 % of all breast cancers. TNBCs quickly acquire drug resistance mechanisms and are inherently resistant to radiotherapy which significantly limits therapeutic options. Thus, there is a need to develop more selective and efficient therapeutic approaches to target this cancer subtype. In this study, we investigate the applicability of MMW radiation as co-factor for prolonged sensitization of TRPV1 receptor to promote the maximal channel activation with minimal tachyphylaxis to increase cancer cell death in TNBC.

Th-Po4-75
Detection Of Keratinizing Squamous Cell Carcinoma Of The Tongue Using Terahertz Reflection Imaging

Seung Jae Oh1; Young Bin Ji2; Jung Min Kim3; Young Han Lee4; Yuna Choi5; Da Hee Kim4; Yong-Min Huh6; Yoon Woo Koh7; Jin-Suck Suh6
1Yonsei University, Republic of Korea; 2Gimhae Biomedical Center, Gimhae Industry Promotion & Biomedical Foundation, Republic of Korea; 3Yonsei University, Department of Otorhinolaryngology, Severance Hospital, Republic of Korea; 4Yonsei University, Department of Radiology, Severance Hospital, Republic of Korea; 5Yonsei University, Yonsei University College of Medicine, Republic of Korea; 6Yonsei University, YUHS-KRIBB Medical Convergence Research Institute, Republic of Korea; 7Yonsei University, Yonsei University, 2Department of Otorhinolaryngology, Severance Hosp, Republic of Korea

We detected keratinizing squamous cell carcinoma (SCC) of the tongue using terahertz reflection imaging and reported unexpected characteristics that THz reflection intensity of tumor was low in normal regions

Th-Po4-76
Application Of Infrared-Free Electron Laser For Amyloidosis Therapy

Takayasu Kawasaki1; Heishun Zen2; Akinori Irizawa3; Koichi Tsukiyama1; Kazuhiro Nakamura4
1Tokyo University of Science, Japan; 2Kyoto Universiy, Japan; 3Osaka University, Japan; 4Gunma University, Japan

Infrared-free electron laser (IR-FEL) is a synchrotron-radiation based coherent laser light that is generated by an accelerated electron beam as a light source. Its oscillation wavelengths are tunable within the mid-infrared region from 5 to 10 µm, and various resonant wavelengths for stretch vibrational modes of C=O, C-O, C=C, and C-N bonds, and bending vibrational modes of N-H, C-H, and O-H bonds are contained in this region. As an application of IR-FEL to biomedical field, we show here efficient dissociation of amyloid fibrils that are cause of serious amyloidosis by using the IR-FEL tuned to amide band.

Th-Po4-77
Terahertz Spectra Study On Chemical Constituents From Amalocalyx Yunnanesis

Ting Zeng1; Sen Gong2; Jun Zhou2
1Chengdu Medical College, China; 2University of Electronic Science and Technology of China, China

In this work, we measured the absorption spectra of seven compounds isolated from Amalocalyx yunnanensis Tsiang (Apocynaceous) in the frequency range from 0.2 to 2.0 THz by terahertz time-domain spectroscopy (THz-TDS). From the observed characteristic absorption peaks, it is found that the luteolin (a), luteolin-7-O-ÃfŽÃ,²-D-glucopyranoside (b), amalogenin A (c) and amaloside B (d) show remarkable similarities and differences. This is because that (b) is a glycoside with aglycone (a), as well as (c) is the aglycone of (d). Accordingly, THz-TDS is an efficient method for identifying chemical constituents of natural products.

Th-Po4-78
Optimization Of Data Fitting Algorithm For Tissue Dielectric Properties In THz-band Using Genetic Algorithm

Xuefei Ding; Fan Yang; Xiao Yu; Mingxing Li; Bing Gao; Yuxin Fang; Xin Huang
Chongqing University, China

The non-linear least squares method (NLLS) is often used to extract the double Debye parameters. However, to solve NLLS, the traditional Gauss-Newton method depends heavily on the initial values. This paper provides a method to optimize the algorithm, using genetic algorithm (GA) to acquire suitable initial values for the Gauss-Newton method. Computer simulations show that the optimized algorithm extracts more accurate double Debye parameters and fits the data better.

Th-Po4-79
Detection Of Aflatoxin B1and B2 Using Terahertz Meta-biosensor

Rong Zhao1; Cheng Zhang1; Dongqian Xu2; Yuping Yang1
1Minzu University of China, China; 2Hebei University of Economics and Business, China

Aflatoxin B1 and B2 are toxic to humans and widespread in agricultural and food products. Thus, rapid and accurate determination of these substances is essential for the safe consumption of agricultural products and prevention of further detriment to human health. Detection via conventional methods has proven to be time-consuming and complex. Here, we present that a terahertz (THz) metamaterial (MM)-based biosensor shows promising potential for high-sensitivity, quantitative identification of aflatoxin B1 and B2 with extremely small amounts. In addition, the sensing of analyte was demonstrated as a function of content, thickness, and dielectric constant by detailed measurement and simulation.

Th-Po4-80
In Vivo THz Measurements Of Human Skin: Investigating The Dependence On Ethnicity And Arm Dominance

Xavier Barker; Emma Pickwell-MacPherson
The University of Warwick, Department of Physics, United Kingdom

The University of Warwick, The University of Warwick, Department of Physics, United Kingdom
Terahertz radiation is highly sensitive to water content, giving it the potential to be a powerful tool for discerning slight variation in skin. In this work, in vivo measurements exhibit a clear difference between Asian male and Caucasian male skin, whilst showing no statistically significant difference between right (dominant) and left volar forearms. This paper demonstrates how sensitive THz skin measurements are, and highlights the potential of applying this technology for dermatology research.

Th-Po4-81
Principle Of A Subcarrier Frequency-modulated Continuous-wave Radar In The Terahertz Band Using A Resonant-tunneling-diode Oscillator

Yusuke Shirakawa1; Adrian Dobroiu1; Safumi Suzuki1; Masahiro Asada1; Hiroshi Ito2
1Tokyo Institute of Technology, Japan; 2Kitasato University, Japan

We introduce a new principle for distance measurement using terahertz waves. The method relies on the frequency-modulated continuous-wave radar technique, in which the sawtooth frequency modulation is applied to a subcarrier of the terahertz-wave. We used a resonant-tunneling-diode oscillator as the terahertz-wave source. Our first experimental results in verifying the measurement principle are presented.

Th-Po4-82
Time Domain Circuit Representation Of Photoconductive Gaps In Antennas For Pulsed Terahertz Time Domain Systems

Arturo Fiorellini Bernardis; Paolo Sberna; Andrea Neto; Nuria Llombart
Delft University of Technology, Netherlands

Pulsed terahertz time-domain systems rely on antennas printed on photoconductive substrates (PCA), which show extremely fast conductivity transients when illuminated by femto-seconds laser pulses. This work introduces a time domain circuit representation of the PCA transmitter that accounts for time evolving voltages at the terminals of the photoconductive gap; such model is able to explain the saturation phenomena observed in measurements performed under high power laser excitations that previous models could not account for.

Th-Po4-83
Long-time Coherent Integration For Target Detection In Terahertz Radar

Hongwei Li; Chao Li; Shiyou Wu; Guangyou Fang
Institute of Electronics, Chinese Academy of Sciences, China

Coherent integration is a conventional approach to improve detection ability in radar applications, whereas its performance is decreased by migration through range cell due to the motion of target, limiting the time of integration. This problem becomes more severe in terahertz band. This paper introduces Keystone transform to terahertz radar in order to realize long-time coherent integration, aiming to get a successful detection of targets. Moreover, doppler ambiguity is resolved based on intra-pulse interference processing. A simulation is conducted to demonstrate the effective improvement for target detection using Keystone transform in terahertz radar.

Th-Po4-84
Hybrid Beamforming Architectures Of Terahertz Communications

Longfei Yan1; Chong Han1; Qing Ding2
1Shanghai Jiao Tong University, China; 2Shenzhen Institute of Terahertz Technology and Innovation, China

Hybrid beamforming technology is attractive for Terahertz (THz) communications to compensate the huge path loss, owing to the benefits of low hardware complexity and acceptable power consumption. Multiple hybrid beamforming architectures in the THz band, including the fully-connected (FC), array-of-subarray (AoSA) and dynamic array-of-subarray (DAoSA) architectures are investigated in this paper. Furthermore, the analysis and comparisons of the metrics of interest on spectral efficiency and power consumption of these three architectures are elaborated. Furthermore, multiple key open problems associated with the hybrid beamforming technology in the THz band are elaborated.

Th-Po4-85
A THz SAR Autofocus Algorithm Based On Minimum-Entropy Criterion
Shuyun Shi; Chao Li; Guangyou Fang; Xiaojuan Zhang
Institute of Electronics, Chinese Academy of Sciences, China

The minimum entropy autofocusing for terahertz SAR motion compensation is proposed. Minimum entropy is a nonparametric autofocusing algorithm, which estimates the phase errors by minimizing image entropy. It works better in sparse scenes, such as a collection of point scatterers, which is often encountered in terahertz SAR processing. In this paper, the minimum entropy and Newton method are combined to compensate the platform motion errors. The experimental results show that the minimum entropy autofocusing method commonly used in microwave SAR is also applicable to the terahertz band.

Th-Po4-86
W-Band MIMO Radar Array Optimization And Improved Back-projection Algorithm For Far-Field Imaging

Guan Yang; ZiLi Qin; YiCai Ji; GuangYou Fang
Key Laboratory of Electromagnetic Radiation and Sensing Technology, Chinese Academy of Sciences, China

In this paper, a fast back-projection (BP) algorithm based on time-delay surface correction (TSC) for two- dimensional arrays is proposed. For the range interpolation problem caused by the conventional BP algorithm, the echo data distance migration phase correction method is used to avoid range interpolation and improve the efficiency of BP algorithm while ensuring accurate target positioning. And the computational efficiency of the two methods is compared by the simulation. Then an array optimization design scheme using the Simulated Annealing (SA) algorithm and Genetic Algorithm (GA) is proposed for eliminating the grating lobes in the W-band sparse array. The feasibility of this method is verified by simulation.

Th-Po4-87
Compressed Sensing Based Super-Resolution Layer Structure Analysis For Terahertz Time-domain Spectroscopic Imaging System

Hayatomomaru Morimoto; Shouhei Kidera
The University of Electro-Communications, Japan

This paper introduces a super-resolution depth imaging method based on a compressed sensing scheme with reference signal optimization, particular for data obtained out of focus. The effectiveness of our method has been validated through the THztime-domain spectroscopic (TDS) experimental data.

Th-Po4-88
Five-Capillary Cladded Low Loss Anti-resonant Terahertz Fiber

Jakeya Sultana1; MD Saiful Islam1; Cristiano. M. B Cordeiro1; Selim Habib2; Alex Dinovitser1; Brian W.-H Ng1; Mayank Kowshik1; Heike Ebendorff-Heidepriem1; Derek Abbott1
1The University of Adelaide, Australia; 2The University of Central Florida, United States

This paper reports on progress in anti-resonant hollow core waveguide design, showing that five-capillary cladding achieves lower loss, higher bandwidth, as well improved suppression of higher order modes than fibers with a greater number of cladding capillaries for frequencies around 0.4 THz. Three candidate design model results are presented, with application to low cost and low loss THz transmission.

Th-Po4-89
Sidelobe Suppression Of Terahertz Emitters With Horn Antennas

Rabi Shrestha; Jianjun Ma; Daniel M. Mittleman
Brown University, United States

The suppression of sidelobe emission will be a critical need for terahertz wireless data links in order to avoid interference. We demonstrate a strategy for suppression of horn antenna sidelobes using affordable millimeter wave absorbers.

Th-Po4-90
A Sub-Terahertz Retrodirective Antenna Array For Satellite Tracking

Zhongbo Zhu1; Weidong Hu2; Xianqi Lin3; Xiaojun Li1
1The National Key Laboratory of Science and Technology on Space Microwave, China; 2Beijing Institute of Technology, China; 3University of Electronic Science and Technology of China, China

A sub-terahertz retrodirective antenna array is proposed. This array receives 40 GHz navigation signal and accurately retransmits 120 GHz beam in the direction of arrival wave. Simulation results indicate that proposed array with stacked sandwich structure has realized the tracking of the arrival wave. The scanning radiation pattern shows array gain is 23.87 dB at 19.9ÃfÆ'ââ,¬Å¡Ãfâ?sÃ,° when incident angle is 20ÃfÆ'ââ,¬Å¡Ãfâ?sÃ,° with a relative error of only 0.5%, which means there is a lateral error of only 8.7 meters at a transmission distance of 5 kilometers.

Th-Po4-91
THz Links Using Tube Amplifiers And Steerable Beams For Indoor Applications

Cybelle Belem1; Andre Sarker2; Henry Giddens2; Carlos Biurrun3; Carlos Del-Rio Boccio3; Cyril Luxey4; Yang Hao2; Rupa Basu5; Claudio Paoloni5; Guillaume Ducournau6
1IEMN, France; 2QMUL, E14NS, United Kingdom; 3Institute of Smart Cities, Univ Publica de Navarra, Spain; 4Polytech'Lab, Univ Nice Sophia, France; 5Univ Lancaster, United Kingdom; 6IEMN CNRS/Université de Lille, France

We present in this paper an ongoing project will is targeting the combination of several technologies to achieve high-data-rate and long-range links using a mW level source with fast modulation, waveguide coupled to drive a traveling-wave tube amplifier towards a modulated in the 210-250 GHz range. In this project we are also investigating antennas structures, high-gain for outdoor links and using lens or cassegrain design or lower gain systems with steerable capability for indoor links.

Th-Po4-92
Dichroic Filters Development For NOEMA Receivers

Anne-Laure FONTANA; Patrice SERRES; Arnaud BARBIER; Dominique BILLON; Eduard DRIESSEN
Institut de RadioAstronomie Millimetrique (IRAM), France

The NOEMA (Northern Extended Millimeter Array) Interferometer is a Radio-Astronomical Observatory composed of ten 15-m Antennas (two additional antennas are also being constructed) located on the Plateau de Bure, in the French South Alps. Each of these antennas is equipped with a cryogenic millimeter wave heterodyne quadri-band receiver, covering frequencies from 72GHz to 365GHz. The four modules covers respectively the 72-116GHz; 127-179GHz; 200-276GHz and 276-365GHz bands, and each of the four beams currently looks at a different region of the sky. A future major upgrade planned for these receivers is to combine the 72-116GHz and the 200-276GHz beams with a dichroic filter to enable these two beams to observe simultaneously the same region of the sky. For that purpose IRAM has begun to develop in house broadband low loss dichroic filters. Dichroic filters should behave as reflecting mirrors for some wavelengths, and should be transparent for other wavelengths.

Th-Po4-93
Demonstration Of Broadband Anti-reflection Coating Based On Sub-wavelength Structures On Sapphire For Mm-wave Applications

Ryota Takaku1; Tomotake Matsumura2; Haruyuki Sakurai1; Kuniaki Konishi1; Hiroaki Imada3; Shaul Hanany4; Karl Young4; Qi Wen4; Yuki Sakurai5; Nobuhiko Katayama5; Kazuhisa Mitsuda6; Noriko Yamasaki6; Kunimoto Komatsu7; Hirokazu Ishino7; Junji Yumoto1; Makoto Kuwata-Gonokami1
1The University of Tokyo, Japan; 2Kavli IPMU, Japan; 3LAL, France; 4University of Minnesota/Twin Cities, United States; 5Kavli IPMU, Japan; 6ISAS/JAXA, Japan; 7Okayama University, Japan

We developed sub-wavelength structure, broadband anti-reflection coating on C-cut sapphire using ablation with femtosecond laser. We fabricated circular samples with 34.5 mm diameter. The samples have an array of pyramids with a pitch of 0.54 mm and a height of 2.1 mm. Transmittance measurements agree with predictions based on the measured structures and give transmittance larger than 90% between 40 and 180 GHz. We discuss the implication of this demonstrated performance in relation to mm-wave measurements, and specifically in the context of astrophysical measurements of the cosmic microwave background radiation.

Th-Po4-94
Effect Of Idler Terminations On The Conversion Loss For THz Schottky Diode Harmonic Mixers

Divya Jayasankar1; Jan Stake1; Peter Sobis2
1Chalmers University Of Technology, Sweden; 2Omnisys Instruments, Sweden

Efficient and reliable frequency converters, preferably operating at room temperature, are critical components for frequency-stabilizing terahertz sources. In this work, we present the analysis of optimum configurations for Schottky diode based x4, x6, and x8 harmonic mixers operating at 2.3 THz, 3.5 THz, and 4.7 THz respectively. Detailed large-signal analysis of the two basic single-ended Z- and Y-mixers was carried out using a standard Schottky-diode model. For each case, the conversion loss was minimised by finding optimal embedding impedances at IF, RF and LO frequencies. The analysis shows that the Y-mixer has less conversion loss at a low LO pump power. However, the Z-mixer provides reduced loss with increasing harmonic index and pump power due to the associated power dissipation in idler circuits. The results provide preliminary design guidelines for room- temperature frequency converters and their use in phase-locked loop applications.

Th-Po4-95
MIM Junction Under A Source Of Light Distributed

Enrique Moreno; Ernest Michael
University of Chile, Chile

Metal-insulator-metal junctions are tunneling diodes able to operate at very high frequencies, arriving at the optical ones. The quantum tunneling is a stochastic event that depends very much on the insulator thickness. Particularly, in the mid-infrared, the insulator thickness is several orders of magnitude under the diffraction limit, and the electromagnetic field cannot penetrate into the structure. In all papers reviewed, the wave which illuminates the diode, inside the junction, is transformed in an evanescent one. The only way in which the electromagnetic radiation can be introduced into the structure is through a traveling wave of surface plasmon-polaritons. This work is focused on a procedure of light distributed, which by means of Kretschmann and Reather's prism-based configuration, allows introducing the electromagnetic field in the junction, biased the insulator all along its length. In this way, the technique presented here introduces an improvement that increases the diode responsivity considerably.

Th-Po4-96
Wideband Schottky Doubler With High Efficiency And Output Power

Jiangqiao Ding1; Alain Maestrini2; Lina Gatilova2; Shengcai Shi1
1Purple Mountain Observatory, China; 2Observatoire de Paris, France

The 300 GHz power-combined doubler with an improvement of factor of 2 in power handling ability with regards to the single chip doubler will have great potential for building more powerful sources.

Th-Po4-97
Experimental Study Of Harmonic Mixer Using Two HTS YBCO Grain Boundary Josephson Junctions In Series

Mei Yu1; Haifeng Geng1; Tao Hua1; Weiwei Xu1; Zhi Ning Chen2; Jianxin Shi3; Huabing Wang1; Jian Chen1; Peiheng Wu1
1Nanjing University, China; 2National University of Singapore, Singapore; 3Zijin College, Nanjing University of Science and Technology, China

Two high-Tc superconducting YBCO grain boundary Josephson junctions in series as a harmonic mixer is investigated, which has not been reported previously. The research shows that the mixer consisting of two series YBCO Josephson junctions has a larger harmonic number than that with only one junction in heterodyne mixing at zero-voltage bias. One of the advantages of the series-junction mixer is that the total critical current is improved without sacrificing the sensitivity of the junctions in the array that makes the mixer easier to get more microwave induced-steps required by larger harmonic number. Furthermore, the underdamped YBCO GB series-Josephson-junction mixer operated at zero-bias voltage, where the zero-order Shapiro step exists, achieves mutual phase locking of the junctions in the array, resulting in an excellent mixing performance. Thus, the series-underdamp-junction mixer with zero bias is predominant and compact in THz application due to its excellent performance and no dc bias supply.

Th-Po4-98
A Broadband Q-band Dual-Circular Polarizer For Millimeter-Wave VLBI Observations

Moon-Hee Chung
Korea Astronomy & Space Science Institute,Republic of Korea

A 33~50 GHz dual-circular polarizer combining of an OMT(Orthomode Transducer) and a 90-deg differential phase shifter has been developed for Korean VLBI Network. The OMT is based on curved double-ridge structure and the phase shifter is designed using quad-ridge waveguide. The curved double-ridge is easy to be machined and enables the OMT to become very compact. Both components are fabricated using CNC machining with low cost. The preliminary measurement results show a very broadband performance of the circular polarizer for radio astronomical observations. The bandwidth of the designed circular polarizer is around 41 %.

Th-Po4-99
A 2 X 2 Beam Divider For An Array Local Oscillator At 1.37 THz

HAOTIAN ZHU1; Jerome Valentin1; Thibaut Vacelet1; Etienne Herth2; Yan Delorme1; Martina Wiedner1
1LERMA - Observatoire de Paris, France; 2C2N, CNRS, Universités Paris-Sud, Universités Paris-Saclay, France

A 2 x 2 local oscillator beam divider for pumping a hot electron bolometer mixer array is designed at 1370 GHz. Traditional rectangular waveguide based H-plane and E-plane junctions are used to construct the feeding network. Two 400-m thick silicon wafers are used to build the feeding network, and an aluminum plate is used to build the circular horn array. Multilayer micromachining and multilayer stack assembling are the two key technologies employed in building this beam divider.

Th-Po4-100
An Integrated HEB Mixer In A Cryostat With A Cryogenic LO At 2-THz Band

Yoshihisa Irimajiri; Akira Kawakami
National Institute of Information and Communications Technology, Japan

We are developing an HEB mixer at 2-THz band for the measurement of atmospheric O-atom line at 2.06 THz. We demonstrated an integrated HEB mixer in a cryostat with a cryogenic local oscillator (LO). An alignment of the LO into an HEB mixer was made using a cryogenic rotator. We have detected a beat note using this receiver system.

Th-Po4-101
Perspectives On Spectral Resolution In Continuous-Wave Terahertz Spectroscopy At Stand-off Distances

Mathias Hedegaard Kristensen; Pawel C. Cielecki; Esben Skovsen
Aalborg University, Denmark

In this paper, we discuss practical aspects of continuous-wave frequency-domain terahertz spectroscopy measurements at stand-off distances. We highlight benefits of using various detection schemes and system configurations as well as the limitations of the spectral resolution.

Th-Po4-102
Hyperbolic Metamaterial Based Active Tunable Compact THz Source

Nalini Pareek1; Niladri Sirkar2; Anirban Bera3
1CSIR CEERI / Academy of Scientific and Innovative Research, India; 2BITS, Pilani, India; 3CSIR CEERI, India

The unavailability of a compact and tunable THz source has hampered the growth of THz science and technology and therefore has created "the THz gap" which lies between the microwave and visible range of the electromagnetic spectrum. The next generation vacuum electronic devices that can serve to fill this gap require a fusion of concepts that can overcome the limitations of the existing techniques. In this paper the interaction structure based on HMM geometry has been discussed to generate THz radiations. The proposed structure consists of periodic dielectric and graphene multilayer

Th-Po4-103
High-TC Superconducting Kinetic Inductance Detectors For Terahertz Imaging

Gabriele C. Messina1; Valentina Brosco1; Angelo Cruciani2; Lara Benfatto1; Sara Cibella3; Giorgio Pettinari3; Maria Gabriella Castellano3; Alfonso A. Tanga4; Michele Ortolani4; Leonetta Baldassarre4; Marco Vignati2; José Lorenzana1
1Institute for Complex Systems - National Research Council (ISC-CNR), Italy; 2INFN - Sezione di Roma, Italy; 3Institute for Photonics and Nanotechnologies - National Research Council (IFN-CNR), Italy; 4Physics Department, Sapienza University of Rome, Italy

Terahertz imaging techniques have demonstrated huge potential in different fields as medical diagnosis and cultural heritage, but they are limited by low signal-to-noise ratio. A possible approach to overcome this problem could consider the use of more powerful sources, but they are currently not available on the market and can lead to damage of the sample. A different path can be the improving of present detector technologies, such as arrays of microbolometers. In this regard, Kinetic Inductance Detectors based on HTCS, represent a promising alternative, offering the advantages of high sensitivity and the possibility to work at temperatures reachable with compact cryocoolers. In particular, we developed a YBCO based KID prototype, fabricated through a EBL and wet-etching based approach, which demonstrated good performances in the THz range.

Th-Po4-104
Terahertz Inspection Of The Joining Quality Of Industrial Silicon Carbide Ceramics

Maris Bauer1; Michael Döring2; Ulrich Degenhardt2; Fabian Friederich1
1Fraunhofer ITWM, Germany; 2FCT Ingenieurkeramik GmbH, Germany

We present in our contribution first investigations towards quality inspection of the joining of silicon carbide (SiC) ceramics for industrial applications. In terahertz time-domain spectroscopic transmission measurements we find significant transmission through relevant SiC and SiN samples, mainly in correlation with the sample's resistivities. Differences in resistivity at the interfaces of joined ceramics could be used for the evaluation of the quality of these joinings. A sample joined SiC component with an artificial inner structure was imaged with an all-electronic terahertz FMCW radar at 100 GHz in a reflection geometry. The recorded images clearly reveal the inner structure of the component. Based on these first findings, further studies on quality inspection of SiC joinings are being carried out.

Th-Po4-105
Towards Industrial THz Wave Electronic Gas Sensing And Spectroscopy

Ingrid Wilke; Timothy Rice; Matthew Oehlschlaeger; Muhammad Waleed Mansha; Kefei Wu; Mona Hella; Aniket Tekawade
Rensselaer Polytechnic Institute, United States

A demonstration of low-power THz wave electronics (less than 1 mW) for quantitative atmospheric gas absorption spectroscopy in the 220 -- 330 GHz frequency band is presented. Measurements are reported for acetonitrile, methanol, and ethanol, VOCs important in the atmosphere and industrial settings. Measurements are demonstrated for the strongly absorbing acetonitrile vapors, comparable in SNR to previous measurements made with THz time-domain spectroscopy methods, and for pure methanol and ethanol vapors at low pressures (5 and 10 Torr).

Th-Po4-106
Terahertz Spectroscopy Of Adhesive Material Under Various Climatic Conditions

Suma Sindhu Panchagnula1; Dipa Ghindani2; Nilanjan Mitra3; Shriganesh S Prabhu2
1IIT KHARAGPUR, India; 2Tata Institute of Fundamental Research, India; 3IIT, KHARAGPUR, India

Epoxy resin (DGEBA/TETA) is known to be hygroscopic in nature which eventually leads to mechanical performance degradation of the material. Water uptake into the resin system through hydrogen bonding of water molecules with resin can be demonstrated using Terahertz spectroscopic observations.

Th-Po4-107
Terahertz Pulsed Imaging Of Paraffin-Embedded Human Breast Cancer Tissue

Delphine Cerica1; Dinh Nguyen2; Yves Hernandez2; Jacques G. Verly1; Mohamed Boutaayamou1
1University of Liège, Belgium; 2Multitel A.S.B.L. Research and Innovation Center, Belgium

We measured the terahertz (THz) reflection impulse response of paraffin-embedded human breast cancer tissue samples using a THz time domain spectrometer. We then processed the recorded data to generate preliminary images of several maps of extracted time and frequency domain parameters.

Th-Po4-108
Sub-THz Components For High Capacity Point To Multipoint Wireless Networks

Claudio Paoloni1; Sebastian Boppel2; Viktor Krozer3; Rosa Letizia1; Ernesto Limiti4; Francois Magne5; Marc Marilier6; Antonio Ramírez7; Borja Vidal8; Trung Le9; Ralph Zimmerman9
1Lancaster University, United Kingdom; 2FHB, Germany; 3Goethe University of Frankfurt, Germany; 4University of Rome, Tor Vergata, Italy; 5WhenAB, France; 6OMMIC, France; 7Fibernova, Spain; 8Universitat Politècnica de València, Spain; 9HF Systems Engineering GmbH, Germany

The first point to multipoint wireless system at D-band, providing high capacity area sectors fed by high data rate G-band links connected to fiber access points, will be described. The high transmission power provided by novel millimeter wave traveling wave tube will allow an unprecedented range and data rate. A novel MMIC chipset including components built by GaAs and InP processes to realize a full electronics solution for the sub-THz wireless communication system will be described.

Th-Po4-109
Terahertz Direct Detection Behavior Of A Superconducting NbN Bolometer By Noise Thermometry
Hao Gao; Wei Miao; Kangmin Zhou; Shengcai Shi
Purple Mountain Observatory, Chinese Academy of Sciences, China

In this paper, we report the investigation of direct detection behavior of a superconducting niobium nitride (NbN) hot electron bolometer (HEB) based on noise thermometry. The HEB consists of a microbridge made from 5.5 nm thick NbN film and a twin slot antenna for radiation coupling. In the microbridge, hot electron system is generated after radiation pumping and it creates extra noise at RF frequencies. We measured the response of the noise at 0.5-1.8 GHz and the noise equivalent power (NEP) of the superconducting NbN HEB at different bias voltages. The measurement result shows that the superconducting NbN HEB has a noise equivalent power of 1.24x10-12 W/Hz1/2 at its optimal bias point. We also compared the noise equivalent power measured by noise thermometry at two different readout bandwidths. The measured results are found to be in good agreement with the theoretical one.

Th-Po4-110
Improvement Of Ti-based Superconducting Transition Edge Sensors With Dielectric Mirror

Pei-Zhan Li1; Wen Zhang2; Yue Geng1; Jia-Qiang Zhong2; Zheng Wang2; Wei Miao2; Yuan Ren2; Qi-Jun Yao2; Kang-Min Zhou2; Jin-Feng Wang3; Sheng-Cai Shi2
1Purple Mountain Observatory and Key Laboratory of Radio Astronomy and the University of Science and, China; 2Purple Mountain Observatory and Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, China; 3Nanjing Institute of Astronomical Optics & Technology, National Astronomical Observatories, China

We have studied the performance of Ti-based TES on 1550 nm DM. The TES device on DM shows a similar TC as that directly fabricated on quartz substrate. The detection efficiency is ~30%, which can be further improved by inte-grating anti-reflection layer.

Th-Po4-111
Peptide Self-assembling And Lys/His Exchange Features In BDS

Konstantin Motovilov1; Maxim Savinov2; Zarina Gagkaeva1; Boris Gorshunov1
1Moscow Institute of Physics and Technology, Russian Federation; 2Institute of Physics AS CR, Czech Republic

We studied broadband dielectric spectra (10^(-2)-10^(14) Hz) in a wide range of temperatures (10-300 K) and at thoroughly controlled levels of ambient humidity of two peptides built of natural amino acids: n-HFEFHFEF-c and n-FKFEFKFE-c. Preliminary results demonstrate remarkable differences between properties of these two peptide systems with respect to water sorption and consequent spectral peculiarities.

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