39th Int. Conf. on Infrared, Millimeter, and THz Waves
September 14-19, 2014
The University of Arizona, Tucson, AZ
M5 - Poster Session 1
Monday, September 15, 2014 5:30 pm to 7:00 pm
Room: Ballroom South
Chairperson: Jitao Zhang
Broadband "Focus-Free" Terahertz Imaging Using Axicons
Presenter: Martin Koch

We report the use of axicons to achieve broadband "focus-free" imaging in transmission and reflection at terahertz wavelengths. We demonstrate how the use of a broadband terahertz source improves the resolution of the imaging system, and how by using time-of-flight data the axial position and dimension of objects within the large depth of field of the axicon (160 mm) could be determined.

Author(s):
Stefan Busch - Philipps-Universit‰t Marburg
Graham E. Town - Department of Engineering, Macquarie University.
Martin Koch - Philipps-Universit‰t Marburg
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Phase Retrieval And Image Reconstruction With Echoed Amplitude In Terahertz Band
Presenter: Chao Li

Phase retrieval and image reconstruction for THz incoherent imaging was investigated with experimental results. The proposed approach has potential applications in non- destructive detection with low system cost and complexity.

Author(s):
Chao Li - Institute of Electronics, Chinese Academy of Sciences
Guangyou Fang - Institute of Electronics, Chinese Academy of Sciences
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Enhancing Terahertz Image Quality By Finite Impulse Response Digital Filter
Presenter: Lei Hou

Terahertz (THz) pulse imaging can provide not only the image, but also the constituent of the detected object. However, various noises from THz source, detector and other parts will decrease the image quality. In this paper, a THz image of a metal hoop was obtained by pulse THz waves, and the finite impulse response digital filter was used to remove the low frequency noise caused by the unstability of THz source and the image quality was improved.

Author(s):
Lei Hou - Xi'an University of Technology
Xiao Lou - Xi'an University of Technology
Zhijin Yan - Xi'an University of Technology
Hong Liu - Xi'an University of Technology
Wei Shi - Xi'an University of Technology
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Telecentric F-theta Lens For High-Speed Terahertz Reflection Three-Dimensional Imaging
Presenter: Ji Sang Yahng

High-speed terahertz reflection tomography is demonstrated using electronically controlled optical sampling and beam steering. A telecentric f-theta lens is fabricated and used for beam steering. A volume of 100 °ø 100 °ø 7.8 mm3 can be scanned within 40 s, yielding 200 °ø 200 °ø 725 voxels.

Author(s):
Kyong Hwan Jin - Korea Advanced Institute of Science and Technology
Ji Sang Yahng - Korea Research Institute of Standards and Science
Choon-Su Park - Korea Research Institute of Standards and Science
Ho-Soon Yang - Korea Research Institute of Standards and Science
Chi Yup Kim - Korea Research Institute of Standards and Science
Jong Chul Ye - Korea Advanced Institute of Science and Technology
Dae-Su Yee - Korea Research Institute of Standards and Science
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Emissivity Measurement Of High-Tc Superconductive Materials Using Terahertz Passive Imaging System With Background-Limited Sensitivity
Presenter: Norihisa Hiromoto

We have carried out a terahertz (THz) passive measurement of high-Tc superconductive materials down to liquid nitrogen temperature at 1.5-2.5 THz using a 4 K-cryocooled stressed Ge:Ga photoconductive detector. Using the calibration line, which gives the relation between THz signal emitted from sample, emissivity and temperature, we have derived the temperature-dependent THz emissivity of superconductors. The result shows that THz emissivities of superconductive materials steeply change around each superconductive transition temperature. We also demonstrated the THz passive imaging of superconductive wires and successfully obtained THz passive images before and after superconductive transition.

Author(s):
Makoto Aoki - Shizuoka Univ.
Norihisa Hiromoto - Shizuoka Univ.
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A Millimeter Wave/Terahertz 3D Scanner For Wall Painting Investigation
Presenter: Emilio Giovenale

The advantages in utilizing the peculiar features of the THz radiation for the nondestructive diagnostics of artworks has been recently demonstrated. Due the the capability of the THz radiation of penetrating dielectric materials, a typical application is related to the search for hidden paintings or drawings covered by a superimposed layer. At the ENEA center of Frascati a THz imaging system and a THz Free Electron Laser have been utilized to demonstrate the possibility of detecting features of paintings hidden under a layer of gesso. Moreover the phase capabilities of the device make it possible to distinguish the different pigments of the painting, thus realizing a real THz image of the sample. A portable THz imaging system for the study of wall paintings is currently under construction in the framework of the THz-ARTE project. The device design and operating principle will be presented together with preliminary results on test samples.

Author(s):
Emilio Giovenale - ENEA
Andrea Doria - ENEA
Gian Piero Gallerano - ENEA
Marcello Picollo - CNR-IFAC
Kaori Fukunaga - NICT
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Design And Characterization Of Cross Bow Tie Antenna Array For Focal Plane Array In Terahertz Imaging
Presenter: xiaodong Chen

A novel broadband Terahertz antenna design covering 100- 600 GHz is developed as imaging pixel of THz focal plane array. Proposed focal plane array consist of novel cross bow tie antenna on quartz substrate behind the quartz hyper hemispherical lens. FPA performance is studied at low and high frequencies to determine the pixel pitch and number of effective pixels. Off axis performance of FPA is studied carefully to form a densely packed FPA with uniform patterns to high resolution imaging system. Some geometric variations are also made to improve off axis pixel patterns and overcome the reflection losses from lens. Uniformity of far field patterns is achieved by proper placement of adjacent pixels.

Author(s):
Amna Mir - Beijing university of Posts and Telecommunications
Junsheng Yu - Beijing University of Posts and Telecommunication
xiaodong Chen - Beijing university of posts and telecommunications and Queen marry university of London
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140 GHz Active Imaging Systems Based On FMCW Radar
Presenter: Sergei Kuznetsov

The first experimental results of developing an original active imaging system based on a frequency modulated continuous wave radar (FMCWR) operating at 140 GHz are presented. The short-range (1 m) and long-range (1-30 m) prototypes of 2D and 3D FMCWR imagers utilizing different raster scanning techniques with a capability of tracking the absolute object distance and velocity are discussed. The imagers' performance applicable to the tasks of security and nondestructive material quality inspection is analyzed.

Author(s):
Sergei Kuznetsov - Novosibirsk State University
Sergei Makarov - Novosibirsk State University
Valery Koshelenko - Novosibirsk State University
Mikhail Astafev - Novosibirsk State University
Andrey Arzhannikov - Novosibirsk State University
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CANCELLED: Total Variance Regularization For Millimeter-wave Holographic Imaging
Presenter: Lingbo Qiao

Millimeter-wave (MMW) holographic imaging has been demonstrated effective for security surveillance, especially for personnel surveillance. However, coherent effects, such as speckle, and the low signal-to-noise (SNR) may destroy image clarity and make it difficult for automatic target recognition. In order to improve the image quality of MMW image, an iterative reconstruction method based on total variance regularization is presented in this paper. Experiments based on a 35GHz MMW holographic imaging system have been done to verify the proposed method. The results preserve better edges and the disturbance of speckle and noise is reduced.

Author(s):
Lingbo Qiao - Tsinghua University
Yingxin Wang - Tsinghua University
Ziran Zhao - Tsinghua University
Zhiqiang Chen - Tsinghua University
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CANCELLED: System Analysis And Image Processing For Millimeter-wave Holographic Imaging
Presenter: Zheng Li

Millimeter-wave holographic imaging system can acquire 3D images and is nonionzing, which especially fits personnel imaging. Widely utilized linear antenna arrays provide high scanning speed as well as non-uniformity artifacts. In this paper, we developed a set of calibration methods and image denoising algorithms to eliminate the influences of system errors including response non-uniformity, transmission delay and background scattering. The experimental results prove that the calibration methods contribute to non-uniformity reduction. The denoising algorithm is efficient in eliminating the disturbances of artifacts related to sub-sampling.

Author(s):
Zheng Li - Department of Engineering Physics, Tsinghua University
Ziran Zhao - Department of Engineering Physics, Tsinghua University
Zongjun Shen - Nuctech Company Limited
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Traveling Wave Amplification From Multi-Beam Slow Wave Structures For High Power Millimeter And THz Wave Generation
Presenter: Young-Min Shin

In an effort to develop compact millimeter and THz wave radiation power sources, two types of traveling wave amplification concept with multi-beam have been studied using Pierce small signal analysis and particle-in-cell (PIC) simulation. Our prior work includes theoretical and numerical assessment on performance of the aluminum-nitride (AlN)-loaded multi-beam structure, indicating that the TM31-mode is amplified with 26 - 30 dB/beam at 64 - 84 GHz with three elliptical beams, simultaneously suppressing lower order modes (TM11, and TM21). The same analysis also shows that multi-staged cascading enables > 50 W of radiation power with 30 dB gain, which could be integrated on a single board substrate with multi-beam emitters by micro-fabrication. More schemes to improve device performance and to reduce physical sizes are continuously explored in advancing millimeter and sub-millimeter power radiation sources.

Author(s):
Young-Min Shin - Northern Illinois University
Andrew Palm - Northern Illinois University
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Terahertz Optical Kerr Effect Spectroscopy Of Biological Molecules
Presenter: Thomas Harwood

We have used OKE spectroscopy to detect terahertz modes of biological molecules increasing in complexity, in aqueous solution. These measurements are sensitive to conformation and solvation, which are essential in protein dynamics. Thus, terahertz-OKE spectroscopy has the potential to be applied as an invaluable tool for the analysis of biochemical reactions.

Author(s):
Thomas Harwood - University of Strathclyde
David Turton - University of Glasgow
Elizabeth Ellis - University of Strathclyde
Adrian Lapthorn - University of Glasgow
Klaas Wynne - University of Glasgow
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Research Of Dielectric Properties Of Wood At Frequencies 0.1 ˜ 0.5 THz
Presenter: Grigorii Dunaevskii

The interaction of electromagnetic radiation at 0.1 -- 0.5 THz with four wood species, such as birch (Betula pendula Roth), spruce (Picea obovata), cedar (Pinus sibirica) and pine (Pinus silvestris L.) was investigated. Samples used for measuring are smoothly polished wood plates with different thicknesses ranging from 3 mm to 8 mm. Moisture of wood was fixed after measuring and was equal 2 % and 4 %.. The measurements were performed at room temperature, which did not leave the interval 21 ˜ 23∞ C. Wood samples were prepared in longitudinal and transverse directions relative to the fibers of wood. The complex permittivity was measured by quasioptical Mach-Zahnder Interferometer with backward-wave oscillator as a radiation source. Area of anomalous dispersion is observed with a maximum of the dielectric loss at 250 GHz for a sample with transverse fiber directions of the wood. The selective absorption of electromagnetic energy in a cross section appears due to a resonance effect, which can be explain by the equality of the wavelength of electromagnetic radiation and the size of basic wood cells - tracheids - in this direction, since the transverse dimension of such cells is from 0.01 to 0.1 mm. In the longitudinal direction the length of ones is much greater than the wavelength - 0.5 ˜ 10 mm. The comparative analysis shows that the values of the relative permittivity for longitudinal sections of higher than the transverse by 10 ˜ 15 %. As for dielectric loss assessment is difficult because of its small values. The main role in the observed selective absorption plays the presence of water and cell shape anisotropy. These measurement results can be used for the non-destructive evaluation of wood and the modeling of permittivity for the remote sensing of the Earth.

Author(s):
Grigorii Dunaevskii - National Research Tomsk State University
Valentin Syslyaev - National Research Tomsk State University
Kirill Dorozhkin - National Research Tomsk State University
Tatiana Kochetkova - National Research Tomsk State University
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Liquid Crystal Materials With High Birefringence For THz Applications
Presenter: Urszula Chodorow

The subject of this work are two liquid crystal nematic materials 2002B and 2002C with high birefringence value in the frequency range 0.3 -- 3.0 THz. We present refractive indices and absorption coefficients for ordinary and extraordinary direction and birefringence of measured liquid crystals. Time-Domain spectroscopy was used for measurements of liquid crystals properties.

Author(s):
Urszula Chodorow - Military University of Technology
Olga Chojnowska - Military University of Technology
Katarzyna Garbat - Military University of Technology
Jakub Herman - Military University of Technology
Janusz Parka - Military University of Technology
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Development Of Thick Orientation Patterned GaP For Frequency Conversion In The Mid IR And THz Region
Presenter: Shiva Vangala

Hydride vapor phase epitaxial growth of thick GaP was performed on plain substrates and on half-patterned templates in order to determine the favorable pattern orientations and the optimal growth conditions for thick device quality orientation patterned GaP. Initial optical characterization and testing of frequency conversion in the grown OPGaP are in progress.

Author(s):
Shiva Vangala - Air Force Research Laboratory
Vladimir Tassev - Air Force Research Laboratory
Martin Kimani - Air Force Research Laboratory
Michael Snure - Air Force Research Laboratory
Mathew Mann - Air Force Research Laboratory
Rita Peterson - Air Force Research Laboratory
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Temperature-dependent Refractive Indices Of A 1mol % MgO-doped Stoichiometric LiTaO3 Crystal At The THz Frequency Range
Presenter: Kyu-Sup Lee

Refractive indices of a 1 mol % MgO-doped stoichiometric LiTaO3 (SLT) crystal in the region of 0.85 ~ 1.59 THz and for the temperature range of 80 ~ 300 K were deduced via the terahertz generation process using a fanned-out periodically poled SLT. In addition, temperature-dependent Sellmeier equation was derived.

Author(s):
Kyu-Sup Lee - Gwangju Institute of Science and Technology (GIST)
Shunji Takekawa - National Institute for Materials Science
Kenji Kitamura - National Institute for Materials Science
Do-Kyeong Ko - Gwangju Institute of Science and Technology
Nan Ei Yu - Gwangju Institute of Science and Technology
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Electromagnetic Response Of Anisotropic Polystyrene Composite Materials Containing Oriented Multiwall Carbon Nanotubes
Presenter: Grigorii Dunaevskii

Polystyrene composites with 0.25 wt. % loading of oriented multiwall carbon nanotubes (MWCNTs) have been produced by stretching method. The composites showed anisotropy of transmission of millimeter wave radiation depending on sample orientation relative to the polarization of electromagnetic wave.

Author(s):
Victor Zhuravlev - Tomsk State University
Grigorii Dunaevskii - Tomsk State University
Valentin Suslyaev - Tomsk State University
Alexander Badin - Tomsk State University
Micael Kanygin - Nikolaev Institute of Inorganic Chemistry SB RAS
Olga Sedelnikova - Nikolaev Institute of Inorganic Chemistry SB RAS
Lubov Bulusheva - Nikolaev Institute of Inorganic Chemistry SB RAS
Alexander Okotrub - Nikolaev Institute of Inorganic Chemistry SB RAS
Kirill Dorozhkin - Tomsk State University
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Investigation Of Dielectric And Conductivity Properties Of YSZ
Presenter: Branimir Pejcinovic

A THz TDS study of permittivity and conductivity properties of new variant of Yttria-Stabilized-Zirconia (YSZ) produced using tape-cast method is reported. This study extends the frequency coverage of some of the previously published work. We find a general agreement with published results but the frequency gap in the mm-wave range needs to be measured more carefully before final conclusions on the properties of YSZ can be drawn.

Author(s):
Branimir Pejcinovic - Portland State University
Praveen Sekhar - Washington State University Vancouver
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NIR And MWIR Transparent Liquid Crystals
Presenter: Jakub Herman

A fully deuterated liquid crystal with low absorption in mid-wave infrared (MWIR) is developed. This liquid crystal serves as an important nematic material for future development of low-loss infrared IR liquid crystals and devices. New synthetic approach of perdeuterated 4'-pentylbiphenyl-4-carbonitrile, known as PCB or 5CB, one of the most widely known nematic liquid crystal, has been developed. Title compound has been synthesized in cross-coupling reaction of deuterated 4-cyanophenylboronic acid with perdeuterated 4-pentylchlorobenzene. Presented synthetic path can be easily applied to the synthesis of other homologues of alkylcyanobiphenyl (nCB) series as well as for partially deuterated nCBs.

Author(s):
Jakub Herman - Military University of Technology
Przemys≥aw Kula - Military University of Technology
Piotr Harmata - Military University of Technology
Micha≥ CzerwiÒski - Military University of Technology
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Low-Pressure Gas Spectroscopy Using Terahertz Frequency Synthesizer Traceable To Microwave Frequency Standard Via Dual Optical Comb
Presenter: Takeshi Yasui

We constructed a widely and continuously tunable terahertz frequency synthesizer traceable to a microwave frequency standard. Photomixing of two optical frequency synthesizers, linked to the frequency standard via dual optical frequency combs, makes this THz synthesizer traceable to the frequency standard. To demonstrate the potential of wide and continuous tunability in the THz synthesizer, we tuned its output frequency by 120 GHz continuously around 0.65 THz by using a uni-traveling-carrier photodiode as a photomixer and applied it for precise THz spectroscopy of low-pressure molecular gas. This THz synthesizer will be a powerful tool for broadband, high-precision THz spectroscopy.

Author(s):
Takeshi Yasui - The University of Tokushima
Hiroto Kimura - The University of Tokushima
Yi-Da Hsieh - The University of Tokushima
Hajime Inaba - National Institute of Advanced Industrial Science and Technology
Kaoru Minoshima - The University of Electro-Communications
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Wide Range And High Resolution CW THz Spectrometer Combined With GaP THz Signal Generator And Mechanically Cooled Bolometer
Presenter: Tetsuo Sasaki

We have constructed a CW THz spectrometer, of which light source was a THz Signal Generator on the principle of Difference Frequency Generation in a GaP crystal, and of which detector was a mechanically cooled bolometer on the principle of Transition Edge Superconductor of Niobium. A liquid helium free wide frequency range high-resolution CW-THz spectrometer could be realized. Combining with the all solid state pump light sources developed mainly for optical communication and mechanical cooler to keep bolometer device at low temperature all the time, the spectrometer is now working as nonstop system.

Author(s):
Tetsuo Sasaki - Shizuoka University
Tadao Tanabe - Tohoku University
Jun-ichi Nishizawa - Tohoku University
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Extraction Of Beat Signal Between Dual THz Combs Using Dual THz Spectrum Analyzers
Presenter: ryuji ichikawa

It is crucial in asynchronous-optical-sampling THz time-domain spectroscopy or dual THz comb spectroscopy to suppress the timing jitter of the mode-locked frequency between two femtosecond lasers or frequency fluctuation of a beat signal between two THz combs because the fluctuation of them distorts the linearity of frequency scale in the spectrum. In this paper, dual THz spectrum analyzers were effectively used to extract a beat signal between dual THz combs around 0.1 THz. The resulting beat signal has a linewidth below 1 Hz and a signal-to-noise ratio of 20 dB. Furthermore, the extracted beat signal was used to suppress the remained timing jitter effectively.

Author(s):
ryuji ichikawa - University of Tokushima
Hiroto Kimura - University of Tokushima
Kenta Hayashi - University of Tokushima
Hajime Inaba - National Institute of Advanced Industrial Science and Technology
Kaoru Minoshima - University of Electro-Communications
Takeshi Yasui - University of Tokushima
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A Waveguide Filter Bank For Millimeter-Wave Spectroscopy
Presenter: George Che

We present the design concept and our latest simulation results for a novel low (R~100) to moderate (R~1000) resolution multi-pixel direct detection spectrometer operating at millimeter (mm) and submillimeter (submm) wavelengths. This design implements a transmission line filter bank using rectangular waveguide resonant cavities as a series of frequency filters, each terminated by a lumped-element kinetic inductance detector (LEKID).

Author(s):
George Che - Arizona State University
Philip Mauskopf - Arizona State University
Matthew Underhill - Arizona State University
Hamdi Mani - Arizona State University
Christopher Groppi - Arizona State University
Sean Bryan - Arizona State University
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THz Subwavelength Metamaterials Polarization Insensitive Modulators
Presenter: Hailin Cui

The polarization response of THz wavelength metamaterials modulators have been researched, and a special modulator structure has been proposed, simulated and fabricated. Compared with the traditional split ring resonator modulators which are all polarization sensitive, the new structure has properties of polarization insensitive. The structure is a completely symmetrical metal structure and has the perfect characteristics of the polarization insensitive.

Author(s):
Hailin Cui - Capital Normal University
bo Su - Capital Normal University
Jingsuo He - Capital Normal University
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Reflectance Spectroscopy Of Pigments In MIR To THz Spectral Range
Presenter: Sergey Shilov

Library of paint pigments in 120-0.9 THz spectral range was created using FTIR spectrometer with fixed optical components. Library will allow remote identification of unknown pigments in object of art.

Author(s):
Sergey Shilov - Bruker Optics
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Tunable Inter-Landau-level Lasing In Resonant Tunneling Multiple Quantum Well Structures
Presenter: Yury Mityagin

A mechanism of frequency tunable terahertz emission based on inter-Landau level transition in cascade quantum well structures under a condition of sequential resonant tunneling was proposed and theoretically proved.

Author(s):
Yury Mityagin - P.N.Lebedev Physical Institute
Maksim Telenkov - National University of Science & Technology "MISIS"
Piotr Kartsev - National Research Nuclear University ìMEPhIî
Vladislav Agafonov - P.N.Lebedev Physical Institute
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Intense And Short Millimeter Wave Pulse Generation By Using A Gyrotron As A Light Source
Presenter: Seitaro Mitsudo

In order to realize pulsed ESR measurements by using a Gyrotron oscillator. 154 GHz gyrotron output had been successfully sliced to intense and short millimeter wave pulses (10 ns and 20 ns) with arbitrary delay time t by using a light controlled semiconductor shutter system.

Author(s):
Seitaro Mitsudo - University of Fukui
Toshihiro Tanaka - University of Fukui
Chihiro Umegaki - University of Fukui
Yutaka Fujii - University of Fukui
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3D Printing Of Aspherical Terahertz Lenses And Diffraction Gratings
Presenter: Andrew Squires

We present a series of aspherical lenses and diffraction gratings 3D printed for use as optical components in terahertz spectroscopy systems. Commercially available plastics for 3D printing (VisyJet Crystal, Acrylonitrile Butadiene Styrene (ABS) Plastic and acrylic based polymers) have also been characterized via Terahertz Time Domain Spectroscopy (TDS) and two-color wave photomixing. In addition, characterization has been achieved using synchrotron radiation at the Australian Centre for Synchrotron Science. The lenses were found to have a focal length of (35±2) mm suggesting high spatial resolutions might be achieved. This result agrees with the calculated focal length of 35.5 mm. Control over output maxima and beam splitting of the diffraction gratings is observed with easily made adjustments in the 3D printing design process. A square grating produced was found to be a (78±2)% efficient beam splitter. The blazed grating produced demonstrated an efficiency of (38±1)% in the first order diffraction maxima. These were taken using radiation at 0.28 THz using the two-color wave photomixing system.

Author(s):
Andrew Squires - University of Wollongong
Evan Constable - University of Wollongong
Roger Lewis - University of Wollongong
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Evaluation Of Radio-over-Fiber Characteristics At Airport For Optically-Connected Runway Surface Foreign Object Debris Detection Millimeter-Wave Radar
Presenter: Shunichi Futatsumori

Although small in volume, debris on the airport surface may cause severe damage to aircraft. To detect these obstacles, we have been developing optically-connected airport surface foreign object debris (FOD) detection 96 GHz millimeter- wave radar systems. The proposed runway surface FOD detection system will be installed in airports. This paper discusses the evaluation results of radio-over-fiber characteristics at Sendai airport, Japan. The millimeter-wave radar baseband signal, which is about 8 GHz, is transmitted to the radar antenna using optical fibers. The results show that the 8 GHz RF signal loss due to the buried fiber cables is less than 5 dB for the 2,100 m length fiber cable. In addition, other RF signal loss due to the 5,900 m length fiber cable and several fusion splicing points is about 7 dB.

Author(s):
Shunichi Futatsumori - Electronic Navigation Research Institute
Kazuyuki Morioka - Electronic Navigation Research Institute
Akiko Kohmura - Electronic Navigation Research Institute
Kunio Okada - Electronic Navigation Research Institute
Naruto Yonemoto - Electronic Navigation Research Institute
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Radar Cross Section Of The Metal Sphere From Microwave To The Optical Frequency
Presenter: Ruijun Wang

Considering the frequency dispersion of the complex dielectric permittivity for metals, the accurate radar cross section (RCS) of a copper sphere is given from microwave to the optical frequency. By investigate the effects on the RCS caused by the dispersion of metals, we show that polished copper sphere can be treated as perfectly electrical conductor (PEC) for the RCS prediction at terahertz frequencies.

Author(s):
Ruijun Wang - National University of Defense Technology
Yuliang Qin - National University of Defense Technology
Bin Deng - National University of Defense Technology
Hongqiang Wang - National University of Defense Technology
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Analysis Of Polarisation Diversity At Terahertz Frequencies
Presenter: Nick Lawrence

Terahertz frequencies o ffer the possibility of high resolution surveillance capabilities in areas requiring high levels of security. Terahertz imaging offers wavelengths providing high resolution with modest apertures while remaining able to penetrate clothing. In addition, they are not significantly a ffected by scatterers such as dust, fog and rain particles. Signal-to-noise ratio, dependent on antenna alignment, plays a critical role in providing high fidelity images. In this paper, performance of this ratio is analysed for the case of mutual orthogonality in three dimensions. Multiple-input multiple-output polarization diversity off ers a way of improving system performance without the limitations associated with spatial diversity. In the general case of a Rician fading channel the inclusion of a third orthogonal dipole may provide a useful additional degree of freedom and allow high capacity irrespective of antenna alignment. We develop a novel Rician fading channel model for a tri-orthogonal half-wave dipole transmitter and receiver imaging system employing polarization diversity. Capacity is observed to be more robust than that of a dual-polarized system over the majority of a field of view. Simulation results have been compared to reference papers and show excellent agreement. The model design is applicable to other areas of high capacity systems research.

Author(s):
Nick Lawrence - University of Adelaide
Brian Ng - University of Adelaide
Hedley Hansen - DSTO
Derek Abbott - University of Adelaide
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Analysis Of Millimetre-Wave Polarisation Diverse MIMO Capacity
Presenter: Nick Lawrence

Millimeter-waves o ffer the possibility of wide bandwidth and consequently high data rate for wireless communications. For both uni- and dual-polarized systems, signals sent over a link may suff er severe degradation due to antenna misalignment. Link robustness may be enhanced by the use of mutual orthogonality in three dimensions. In the general case of a Rician fading channel the inclusion of a third orthogonal dipole may provide a useful additional degree of freedom and allow high capacity communication in any unit vector direction. Multiple-input multiple-output polarization diversity off ers a way of improving signal reception without the limitations associated with spatial diversity. It additionally allows for polarization-time block coding at the transmitter and maximal ratio combining at the receiver. We develop a novel Rician fading channel model for a millimeter-wave tri-orthogonal half-wave dipole transmitter and receiver employing polarization diversity. Our simulation extends analysis into a three-dimensional field of view representation fully exploiting individual channel paths. Capacity is observed to be more robust than that of a dual-polarized system over the majority of a field of view.

Author(s):
Nick Lawrence - University of Adelaide
Brian Ng - University of Adelaide
Hedley Hansen - DSTO
Derek Abbott - University of Adelaide
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Resonant-tunneling-diode Oscillator With High-frequency Modulation Structure For High-capacity Terahertz Communication
Presenter: Yu Ikeda

We fabricated a novel resonant-tunneling-diode terahertz oscillator with high-frequency modulation structure for high-capacity terahertz communication and measured the frequency response using vector network analyzer. A very high cut-off frequency of 30 GHz in intensity modulation was obtained by the device oscillating at 350 GHz with reduced MIM capacitor of 0.7 pF.

Author(s):
Masahiro Asada - Tokyo Institute of Technology
Yu Ikeda - Tokyo Institute of Technology
Safumi Suzuki - Tokyo Institute of Technology
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600 GHz HD-TV Transmission Combining UTC-PD And Heterodyne Receiver
Presenter: Guillaume Ducournau

We propose a 600 GHz data transmission using the combination of a photonic emission using an uni-travelling carrier photodiode and an electronic detection. We report a high-definition television transmission at this carrier frequency with a very low power at the receiver. Only 10 nW of THz power at 600GHz were sufficient to ensure a successful high definition video transmission. This combination of photonics at emission and heterodyne detection lead to achieve THz wireless links with a safe level of electromagnetic exposure.

Author(s):
Guillaume Ducournau - IEMN - UniversitÈ Lille 1
Fabio Pavanello - IEMN - UniversitÈ Lille 1
Alexandre Beck - IEMN - UniversitÈ Lille 1
Lucie Tohme - Univ Montpellier 2
Stephane Blin - Univ Montpellier 2
Philippe Nouvel - Univ Montpellier 2
Emilien Peytavit - IEMN - UniversitÈ Lille 1
Mohammed Zaknoune - IEMN - UniversitÈ Lille 1
Jean-Francois Lampin - IEMN - UniversitÈ Lille 1
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Submillimeter Polarimetry With PolKa, A Reflection-type Modulator For The APEX Telescope
Presenter: Giorgio Siringo

Imaging polarimetry is an important tool for the study of cosmic magnetic fields. In our Galaxy, polarization levels up to 10% are measured in the submillimeter dust emission from molecular clouds and in the synchrotron emission from supernova remnants. Only few techniques exist to image the distribution of polarization angles, tracing the plane-of-sky projection of the magnetic field orientation. At submillimeter wavelengths, polarization is either measured as the differential total power of polarization-sensitive bolometer elements, or by modulating the polarization of the signal. Bolometer arrays such as LABOCA at the APEX telescope are used to observe the continuum emission from fields as large as ~ 10 minutes of arc. Here we present results from the commissioning of PolKa, a reflection-type polarimeter for LABOCA. Our map of the polarized synchrotron emission from the Crab nebula is in agreement with structures observed at radio and optical wavelengths. The linear polarization measured in OMC1 agrees with results from previous studies, while the high sensitivity of LABOCA enables us to also map the polarized emission of the Orion Bar, a prototypical photon-dominated region. In this work we demonstrated that PolKa, a reflection-type polarimeter installed in the warm optics of the bolometer camera LABOCA, can provide reliable measurements of the polarization of cosmic dust and synchrotron emission at submillimeter wavelengths, across fields as large as ~10'.

Author(s):
Giorgio Siringo - ESO / ALMA
Helmut Wiesemeyer - Max-Planck-Institute for Radio Astronomy
Talayeh Hezareh - Max-Planck-Institute for Radio Astronomy
Ernst Kreysa - Max-Planck-Institute for Radio Astronomy
Axel Weiss - Max-Planck-Institute for Radio Astronomy
Karl Menten - Max-Planck-Institute for Radio Astronomy
Frederic Schuller - European Southern Observatory
Attila Kovacs - University of Minnesota
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Effect On Viscosity Of Cellulose Derivatives Against Pseudo-polymorphism Conversion Of Amorphous Theophylline Using A Terahertz Spectroscopy
Presenter: Tomoaki Sakamoto

Effect on viscosity of cellulose derivatives against pseudo-polymorphism conversion from an amorphous theophylline to theophylline anhydride form during a pharmaceutical manufacturing process was investigated using a terahertz spectroscopy. In order to investigate an effect on viscosity of binders against pseudo-polymorphism conversion of an amorphous theophylline, cellulose derivatives were used as a binder to prepare granules for a tableting. The start times of conversion to anhydride were almost same except the cellulose derivative which has the lowest viscosity. This tendency was similar between two drying temperatures. Pseudo-polymorphism conversion of amorphous theophylline to an anhydride with a binder had tendency progressing faster at a higher drying temperature. The time-course changes of terahertz absorptions suggest that a rate of pseudo-polymorphism conversion was affected by viscosity of cellulose derivatives.

Author(s):
Tomoaki Sakamoto - National Institute of Health Sciences
Tetsuo Sasaki - Shizuoka University
Noriko Katori - National Institute of Health Sciences
Yukihiro Goda - National Institute of Health Sciences
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Terahertz Investigation Of X-Ray Anti-Imaging Coatings: Spectroscopic Characterization And Imaging
Presenter: Nathan Burford

An investigation of the terahertz properties of x-ray blocking and scattering (XBS) coating materials is performed. Spectral characterizations of the XBS materials reveal much stronger absorption coefficients as compared to the control coatings, as well as significant change in the refractive index. To examine the effectiveness of the coating material, pulsed THz reflection images of coated electronic microchip circuits are obtained. The microchips are covered with XBS coatings of varying thickness. The results demonstrate that this coating can successfully block the incident THz signal between 0.08 and 4 THz if the coating is sufficiently thick. This allowed for the proper thickness of the coating to be determined such that potential intellectual property contained in the microchip design could be protected from THz imaging.

Author(s):
Nathan Burford - University of Arkansas
Magda El-Shenawee - University of Arkansas
Brennen Freiburger - Space Photonics Inc.
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Pulsed THz Imaging For Non-Destructive Testing Of Adhesive Bonds
Presenter: Uli Schmidhammer

Adhesive bonding plays an increasingly important role in diverse industrial fields. Linked to this is the need for non-destructive testing that is not limited on bonded parts for structural applications. Here we demonstrate imaging with a single-shot THz Time Domain spectrometer for the rapid, but precise location and characterization of defects in an adhesive bond. Inclusions of metal, air and dielectrics can be identified. Foreign polymers buried in the polymerized adhesive are revealed thanks to their characteristics in the data range accessible by the THz-TDS approach. The results point out the high contrast and spatial resolution of this non-contact and non-ionizing method.

Author(s):
Uli Schmidhammer - UniversitÈ Paris Sud
Pierre Jeunesse - UniversitÈ Paris Sud
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Numerical Simulation Of DC Equivalent Factor Of THz Calorimeter
Presenter: MOTO KINOSHITA

We have developed a calorimeter for a metrology standard for measuring the power of terahertz (THz) waves. Since the THz calorimeter is based on the thermal balance between heat produced by THz waves and direct current (DC), it requires an equivalent factor for converting from THz to DC power. The DC equivalent factor, which is defined as the ratio between the thermal efficiency of THz and DC powers, was calculated with a thermal simulator based on the finite element method. This factor was estimated to be approximately 1 with a maximum error of 0.7 %, which implies a good equivalence between DC and THz powers, enabling accurate measurement of the absolute power of THz waves.

Author(s):
MOTO KINOSHITA - National Metrology Institute of Japan (NMIJ), AIST
Hitoshi Iida - National Metrology Institute of Japan (NMIJ), AIST
Kuniaki Amemiya - National Metrology Institute of Japan (NMIJ), AIST
Yozo Shimada - National Metrology Institute of Japan (NMIJ), AIST
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Non-destructive Testing Of Glass Fibre Reinforced Plastics With A Full Polarimetric Imaging System
Presenter: Martin Nezadal

A full polarimetric imaging system for the nondestructive testing of glass fibre reinforced plastics in the W-Band (75 to 110 GHz) is presented. It is capable of detecting defects in depths of up to 14.5 mm, and 0.5 mm near the backside of the samples. The full polarimtric information eases the defect detection, since it is not sensitive for the reflection from the backside.

Author(s):
Martin Nezadal - Friedrich-Alexander Universit‰t Erlangen-N¸rnberg
Jan Sch¸r - Friedrich-Alexander Universit‰t Erlangen-N¸rnberg
Lorenz-Peter Schmidt - Friedrich-Alexander Universit‰t Erlangen-N¸rnberg
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Terahertz-Elasticity Measurements On Elastomers
Presenter: Stefan Katletz

The optical parameters (refractive index, absorption coefficient) of opaque dielectric materials can be measured with terahertz (THz) Time-Domain spectroscopy (TDS). By using a THz beam of known polarization and measuring both components of the transmitted THz field, it is possible to determine the birefringence present in an anisotropic material. In this work we used polarization sensitive (PS) TDS to determine the strain-induced birefringence in stretched elastomers.

Author(s):
Stefan Katletz - RECENDT GmbH
Harald P¸hringer - RECENDT GmbH
Michael Pfleger - RECENDT GmbH
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Wideband Frequency-Domain Material Characterization Up To 500 GHz
Presenter: Alireza Kazemipour

A compact quasioptical setup is designed and optimized for material characterization in the frequency range 50GHz to 500GHz. The S-parameters are measured with a commercial Vector Network Analyzer (VNA) together with its mm/sub-mm frequency extenders. A simple practical calibration process is used to determine the diffracted waves on the material surface. A new method is proposed to extract the complex permittivity of the material under closed-form formulas which can help for a parametric error analysis. Several material slabs are measured and the results are presented and analyzed.

Author(s):
Alireza Kazemipour - PTB
Martin Hudlicka - CMI
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A Practical Implementation Of Millimeter And Submillimeter Wave Length On-Wafer S-Parameter Calibration
Presenter: Andy Fung

We present an approach for two-port on-wafer calibration to establish the test reference planes within the substrate of the device under test for the WR3 (220-325 GHz) and WR5 (140-220 GHz) frequency bands. On-wafer calibration is useful for characterizing elements such as transistors for modeling or for the confirmation of circuit models. There are numerous publications for on-wafer calibrations, this discussion differs in that we will present our on-wafer calibration approach with comparison of measurements and simulations of passive structures and that of a transistor model constructed from lower frequency measurements. We discuss practical considerations for the approach we have utilized for high frequency characterization.

Author(s):
Andy Fung - JPL
Lorene Samoska - JPL
Mikko Varonen - JPL
Pekka Kangaslahti - JPL
Stephen Sarkozy - Northrop Grumman Corporation
Richard Lai - Northrop Grumman Corporation
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A Vector Network Analyzer-Based Near Field Scanner For MM-Wave And THz Receivers
Presenter: Kristina Davis

Here we present the methodology and initial results for a new near-field antenna measurement system for sub-millimeter and terahertz receivers. The system is based on a 4-port VNA with two internal sources, which offers reduced complexity and cost when compared to previous systems. The number of external mixers, dividers, and amplifiers necessary for this experimental method is fewer than similar techniques used in this frequency regime. No external source signals are necessary eliminating problems that arise from imperfect phase locking. This system is capable of operating at any frequency where a suitable comb generator exists, and with virtually any heterodyne array receiver.

Author(s):
Kristina Davis - Arizona State University
Christopher Groppi - Arizona State University
Hamdi Mani - Arizona State University
Caleb Wheeler - Arizona State University
Christopher Walker - University of Arizona
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Effect Of Terahertz-Wave Interference On Power Calibration Accuracy
Presenter: Yuma Takida

The frequency characteristics of commercially available pyro-electric detectors have been compared in the range from 0.9 to 2.8 THz by using an intense continuously-tunable terahertz (THz)-wave source. We have found that the THz-wave interference inside the detector has considerable effect on the performance.

Author(s):
Yuma Takida - RIKEN
Naotaka Shiba - Shizuoka University
Takashi Notake - RIKEN
Kouji Nawata - RIKEN
Feng Qi - RIKEN
Shuzhen Fan - RIKEN
Shinichiro Hayashi - RIKEN
Norihisa Hiromoto - Shizuoka University
Hiroaki Minamide - RIKEN
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Repeatability Of Absolute Terahertz Power Measurements Using A Sensitive Calorimeter
Presenter: Hitoshi Iida

In this paper, we report the repeatability of calorimetric measurement of absolute terahertz (THz) power at room temperature. Highly sensitive measurement at a sub-microwatt level was performed by using a calorimeter based on an isothermal temperature-control technique. The experiment was demonstrated at 1 THz using a photomixer as a THz source. Type A uncertainty in repeatability was evaluated to be 2.4% for five repetitions at an incident power of 0.81 É W. A very small drift of 30 pW/s was evaluated as well.

Author(s):
Hitoshi Iida - National Institute of Advanced Industrial Science and Technology
Moto Kinoshita - National Institute of Advanced Industrial Science and Technology
Kuniaki Amemiya - National Institute of Advanced Industrial Science and Technology
Yozo Shimada - National Institute of Advanced Industrial Science and Technology
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Development Of High Accuracy Power Meter In Terahertz Region
Presenter: Shigeki Nishina

A calorimetric power meter has been developed for the highly accurate power measurement of terahertz spatial light. A solid-state terahertz absorber is used when constant terahertz wave absorption occurs due to the dielectric loss of the absorber and the sensor frequency sensitivity can be calibrated by measuring the reflectance characteristics of the absorber in the terahertz region. The stable absorption of the absorber in the terahertz region reduces the variation in sensitivity and provides a highly accurate power measurement. Over a frequency range between 0.4 THz and 10 THz, this system can provide users with a power meter that can measure power with a small uncertainty of 8% (2É–).

Author(s):
Shigeki Nishina - Advantest Corporation
Motoki Imamura - Advantest Corporation
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Uncertainty Calculation Of The D-Band Power Meter Calibration Factor
Presenter: Kazuhiro Shimaoka

An uncertainty calculation method for a D band power meter calibration factor is reported. In this method, an uncertainty propagation from type-B uncertainty components is calculated using the Monte Carlo method. Then, the combined standard uncertainty is calculated as a square root sum of the uncertainty propagation and waveguide flange connection repeatability.

Author(s):
Kazuhiro Shimaoka - National Institute of Advanced Industrial Science and Technology
Moto Kinoshita - National Institute of Advanced Industrial Science and Technology
Katsumi Fujii - National Institute of Information and Communications Technology
Toshihide Tosaka - National Institute of Information and Communications Technology
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Effect Of Time-Delay Errors On THz Spectroscopy Dynamic Range
Presenter: John Molloy

THz spectrometry measurements often exhibit high uncertainties that have previously been attributed to noise. The normalized uncertainties (1-) for three signal processing strategies were evaluated using 40 waveform acquisitions of water vapor (0-3 THz). The normalized uncertainty at 1 THz is 0.15% for the Time-alignment result, representing a x80 improvement compared with direct analysis of all results (11.8%). Rejecting data on the basis of time-alignment and amplitude error also improves the results but is less effective x 3.4 (3.5 %).

Author(s):
David Humphreys - National Physical Laboratory
Mira Naftaly - Natiuonal Physical Laboratory
John Molloy - Industrial Doctoral Centre at Heriot-Watt University
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Application Of THz Radiation To Polyethylene Composite Materials
Presenter: Norbert Palka

We report on the terahertz analysis of the internal structure of ultra-high molecular weight polyethylene composite materials. The visualisation of interfaces between the perpendicularly arranged plies and the identification of stacking faults is possible because the THz refractive index depends on the orientation of fibres in the plies. The thicknesses of all layers of a sample were calculated proportionally to its thickness (3.3-mm) and are equal to about 50 µm, which agrees quite well with other measurements. It is also possible to identify internal defects, i.e. delaminations, in the internal structure of this composite. For this purpose, a 45∞ degree angle between THz polarization and UHMWPE fiber orientation is the preferred configuration. Due to the low THz absorption, even samples with 20 mm thickness can easily be penetrated and approximately 400 plies can be identified. Results of simulations carried out in the 2D FDTD software correspond quite well to the experimental data when we take into account shape, amplitudes and positions of echoes.

Author(s):
Norbert Palka - Military University of Technology
Frank Ospald - 2Fraunhofer Institute for Physical Measurement Techniques IPM, Department of Material Characterization and Testing
Rene Beigang - University of Kaiserslautern, Department of Physics and Research Center OPTIMAS
Danuta Miedzinska - Military University of Technology
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Terahertz Stimulate Specific Signaling Pathways In Human Cells
Presenter: Ibtissam Echchgadda

In recent years, many THz imaging and sensing technologies have been developed, which are increasingly being used in a host of applications. The emergence of these new THz-based technologies has resulted in an increased interest regarding the bioeffects associated with this frequency range. To date, several investigations have been performed to better understand the bioeffects associated with THz radiation. The data from these reports indicate that THz radiation can exert a diverse range of effects at the organism, tissue, and cellular levels. THz radiation can directly impact the structure, functional activity and dynamics of DNA and proteins. Thereby, THz radiation can significantly influence gene expression and consequently can affect the biochemical and phenotypic properties of the exposed cells. THz-induced bioeffects are believed to be primary mediated by the temperature rise generated during exposure (i.e., hyperthermal effects). However, given that THz radiation can strongly interact with water and macromolecules, whose lifetime's scales are in the order of a picosecond, it has also long been argued that THz radiation can exert its effects through coherent excitations and/or nonlinear resonance mechanisms. The question of whether cells exposed to high-power THz radiation exhibited comparable cellular effects than those of hyperthermia still remains answered. In this study, we compared the global effect of a continuous-wave, single-frequency, 2.52 THz radiation and a thermally-matched, bulk-heating (BH) on the expression of mRNAs and microRNAs (miRNAs). Full gene expression profiling was performed using microarray gene chips and cellular responses were evaluated using bioinformatics analysis tools. In our initial set of experiments we sought to determine the temperature rise that would be generated in cells exposed to 2.52 THz radiation for 40 min duration. Our computational and empirical dosimetric data showed that the temperature increased 6∞C during THz radiation exposure. We then used this value to set the thermally-matched BH protocol at 44 ∞C for 40 min. Next to get a comprehensive view of the transcriptional response to THz irradiation, we exposed cells to 2.25 THz radiation or BH protocol and analyzed gene expression levels. We identified the total number of differentially expressed mRNAs and miRNAs that we scored for THz- and BH-exposed cells relative to unexposed (sham) cells. Our results show that 531 and 672 mRNAs were differentially expressed in THz irradiation and BH, respectively. While a total of 66 and 53 miRNAs were significantly changed in THz radiation and BH exposure, respectively. We found that the majority of these altered mRNAs and miRNAs are unique to either THz irradiation or BH. Furthermore, our data also show that THz radiation triggers specific intracellular signaling pathways that were not affected in the BH exposed cells.

Author(s):
Ibtissam Echchgadda - General Dynamics Information Technology
Jessica Grundt - Air Force Research Laboratory
Cesario Cerna - General Dynamics Information Technology
Caleb Roth - General Dynamics Information Technology
Bennett Ibey - Air Force Research Laboratory
Gerald Wilmink - Air Force Research Laboratory
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Quantitative Analysis Of Amino Acids Based On THz Refractive Index Spectra
Presenter: Han Zhang

The qualitative and quantitative analysis of amino acids by terahertz (THz) refractive index spectra is discussed. The frequency band of anomalous dispersion emerging in the spectra is unique for the amino acids, L-glutamine (Gln) and L-histidine (His). The refractive indices of the amino acids were found to be linearly proportional to the concentrations. The calibration models were established to determine concentrations of Gln and His mixture samples by partial least square (PLS) regression method.

Author(s):
Han Zhang - University of Science and Technology Beijing
Zhaohui Zhang - University of Science and Technology Beijing
Xiaoyan Zhao - University of Science and Technology Beijing
Zhi Li - University of Science and Technology Beijing
Fang Yan - University of Science and Technology Beijing
Tianyao Zhang - University of Science and Technology Beijing
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Thermodynamics Of New Piroxicam Derivatives In Terahertz Light
Presenter: Edward Plinski

Polymorphic conversion is a major concern of the pharmaceutical industry. Therefore, it is essential to characterize and quantify polymorphic forms of drugs. Vibrational spectroscopic techniques such as infrared, near-infrared, Raman and, most recently, terahertz pulsed spectroscopy have become popular for solid state analysis since they are fast and non-destructive and allow solid-state changes to be probed at the molecular level. We synthesized and investigated new derivatives of known anti-inflammatory drug piroxicam. One of the research method we applied is a THz spectroscopy presented in this paper. The measurements were performed in a typical THz-TDS arrangement supplied with a fiber laser of 85 fs pulses. The range of the temperature was limited up to 110 ∞C. We show the thermodynamic results for the 2-[4-hydroxy-3-(4-methylbenzoyl)-1,1-dioxo-1,2-benzothiazin-2-yl]-1-(4-phenylpiperazin-1-yl)ethanone -- cross section for 2 THz (66.6 cm-1) in the abstract. Comparing to DSC results, the behavior of the absorbance is not smooth within the accessible temperature range.

Author(s):
Edward Plinski - Wroclaw University of Technology
Berenika Szczesniak-Siega - Wroclaw Medical University,
Boguslaw Fuglewicz - Wroclaw Medical University,
Kacper Nowak - Wroclaw University of Technology
Boguslaw Szlachetko - Wroclaw University of Technology
Przemyslaw Jarzab - Wroclaw University of Technology
Grzegorz Beziuk - Wroclaw University of Technology
Lukasz Sterczewski - Wroclaw University of Technology
Wieslaw Malinka - Wroclaw Medical University
Jan Baran - Polish Academy of Sciences
Marek Drozd - Polish Academy of Sciences
Mariusz Hruszowiec - Wroclaw University of Technology
Stanislawa Plinska - Wroclaw Medical University
Michal Grzelczak - Wroclaw University of technology
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In Situ Relative Phase Measurement Of Two-color Field With Terahertz Radiation
Presenter: Chao Meng

We perform a joint measurement of terahertz waves, high-harmonics and the second harmonic interference generated by ionizing atomic Argon gas in a thin jet moving along the Releigh range of a phase-locked two-color laser field. The measurements show that the optimal phases for terahertz radiation and even-order harmonics change simultaneously along the focal length but the the relative phase between them is locking perfectly at any jet position. This finding implies that terahertz radiation can be used to the relative phase of the two-color field, even the carrier-envelope phase in situ.

Author(s):
Chao Meng - National University of Defense Technology
dongwen zhang - National University of Defense Technology
zengxiu zhao - National University of Defense Technology
Jianmin Yuan - National University of Defense Technology
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High Efficiency, Modular, Optical Pulse Shaping Technique For Tunable, Narrowband THz Generation
Presenter: Etienne Gagnon

We demonstrate a high energy throughput, modular optical laser pulse shaping technique for generating tunable, narrowband, terahertz radiation from the surface of InAs. We achieve a frequency selectivity (f/f) of 0.10 at 1.18 THz and demonstrate an energy throughput of up to 98% using two etalons to create a sequence of optical pulses. In contrast with previously reported schemes, our technique does not rely on interferometry or involve diffractive optical elements, making it robust and relatively inexpensive to implement. This technique can be expanded with additional etalons in order to achieve greater frequency selectivity without sacrificing efficiency.

Author(s):
Samuel Adipa - Franklin & Marshall College
Amy Lytle - Franklin & Marshall College
Etienne Gagnon - Franklin & Marshall College
Far-Infrared Absorption Measurements On Thin Polymer Films
Presenter: Ulrich Schade

Interference fringes in the far-infrared spectra of thin films are the result of the coherent adding up of waves and can influence the spectral interpretation by concealing smaller features. A number of methods have been developed in order to eliminate such oscillating features from the transmittance spectrum. The paper critically evaluates the total transmission-reflection technique and applies the method to quantify the spectra of different polymer films.

Author(s):
Ulrich Schade - Helmholtz-Zentrum Berlin, BESSY II
Eglof Ritter - Humboldt Universit‰t Berlin
Alexis D.O. Bawagan - Carleton University
Jˆrg Beckmann - Federal Institute for Materials Research and Testing
Emad F. Aziz - Helmholtz-Zentrum Berlin und Freie Universit‰t Berlin