scholarly journals Terahertz Spectroscopy of Gas Absorption Using the Superconducting Flux-Flow Oscillator as an Active Source and the Superconducting Integrated Receiver

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7267
Author(s):  
Nickolay V. Kinev ◽  
Kirill I. Rudakov ◽  
Lyudmila V. Filippenko ◽  
Andrey M. Baryshev ◽  
Valery P. Koshelets
Keyword(s):  
Open Space ◽  
Terahertz Spectroscopy ◽  
Near Field ◽  
Gas Absorption ◽  
Thz Spectroscopy ◽  
Single Chip ◽  
Flux Flow ◽  
Practical Applications ◽  
Active Source ◽  
Integrated Receiver

We report on the first implementation of a terahertz (THz) source based on a Josephson flux-flow oscillator (FFO) that radiates to open space. The excellent performance of this source and its maturity for practical applications has been demonstrated by the spectroscopy of gas absorption. To study the radiated power, we used a bolometric detection method and additionally calibrated the power by means of pumping the superconductor–insulator–superconductor (SIS) junction, integrated on a single chip with the FFO. For calibration, we developed a program using the SIS-detected power calculations in accordance with the Tien and Gordon model. The power emitted to open space is estimated to be from fractions of µW to several µW in the wide region from 0.25 THz up to 0.75 THz for different designs, with a maximum power of 3.3 µW at 0.34 THz. Next, we used a gas cell and a heterodyne superconducting integrated receiver to trace the absorption lines of water and ammonia with a spectral resolution better than 100 kHz. Our experiment for gas absorption is the first demonstration of the applicability of the FFO as an external active source for different tasks, such as THz spectroscopy, near-field THz imaging and microscopy.

scholarly journals Temperature dependent poly(L-lactide) crystallization investigated by Fourier transform terahertz spectroscopy

2021 ◽  
Author(s):  
Seiichiro Ariyoshi ◽  
Satoshi Ohnishi ◽  
Hikaru Mikami ◽  
Hideto Tsuji ◽  
Yuki Arakawa ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Absorption Spectra ◽  
Terahertz Spectroscopy ◽  
Thz Spectroscopy ◽  
Frequency Range ◽  
Temperature Dependent ◽  
Thz Absorption

Poly(L-lactide) (PLLA) was investigated by Fourier transform terahertz (THz) spectroscopy over the frequency range of 1.0 – 8.5 THz. THz absorption spectra were acquired for PLLA samples isothermally crystallized at...

Wireless Interface Technologies for 3D IC and Module Integration

2021 ◽  
Author(s):  
Tadahiro Kuroda ◽  
Wai-Yeung Yip
Keyword(s):  
Interface Design ◽  
Near Field ◽  
System Level ◽  
Practical Implementation ◽  
Comprehensive Treatment ◽  
3D Ic ◽  
Practical Applications ◽  
Reconfigurable Processors ◽  
Essential Resource ◽  
Wireless Interface

Synthesising fifteen years of research, this authoritative text provides a comprehensive treatment of two major technologies for wireless chip and module interface design, covering technology fundamentals, design considerations and tradeoffs, practical implementation considerations, and discussion of practical applications in neural network, reconfigurable processors, and stacked SRAM. It explains the design principles and applications of two near-field wireless interface technologies for 2.5-3D IC and module integration respectively, and describes system-level performance benefits, making this an essential resource for researchers, professional engineers and graduate students performing research in next-generation wireless chip and module interface design.

scholarly journals Terahertz Field Confinement in Nonlinear Metamaterials and Near-Field Imaging

Photonics ◽  
2019 ◽  
Vol 6 (1) ◽  
pp. 22 ◽  
Author(s):  
George Keiser ◽  
Pernille Klarskov
Keyword(s):  
Terahertz Radiation ◽  
Terahertz Spectroscopy ◽  
Near Field ◽  
Terahertz Imaging ◽  
Imaging Systems ◽  
Near Field Imaging ◽  
Nonlinear Metamaterials ◽  
Terahertz Devices ◽  
Field Imaging ◽  
Sub Wavelength

This article reviews recent advances in terahertz science and technology that rely on confining the energy of incident terahertz radiation to small, very sub-wavelength sized regions. We focus on two broad areas of application for such field confinement: metamaterial-based nonlinear terahertz devices and terahertz near-field microscopy and spectroscopy techniques. In particular, we focus on field confinement in: terahertz nonlinear absorbers, metamaterial enhanced nonlinear terahertz spectroscopy, and in sub-wavelength terahertz imaging systems.

scholarly journals Asynchronous electric field visualization using an integrated multichannel electro-optic probe

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Shintaro Hisatake ◽  
Junpei Kamada ◽  
Yuya Asano ◽  
Hirohisa Uchida ◽  
Makoto Tojo ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Near Field ◽  
Horn Antenna ◽  
Optimal Placement ◽  
Radar Signal ◽  
Radiation Patterns ◽  
Practical Applications ◽  
Fmcw Radar ◽  
Realistic Situation ◽  
Reference Probe

Abstract The higher the frequency, the more complex the scattering, diffraction, multiple reflection, and interference that occur in practical applications such as radar-installed vehicles and transmitter-installed mobile modules, etc. Near-field measurement in “real situations” is important for not only investigating the origin of unpredictable field distortions but also maximizing the system performance by optimal placement of antennas, modules, etc. Here, as an alternative to the previous vector-network-analyzer-based measurement, we propose a new asynchronous approach that visualizes the amplitude and phase distributions of electric near-fields three-dimensionally without placing a reference probe at a fixed point or plugging a cable to the RF source to be measured. We demonstrate the visualization of a frequency-modulated continuous wave (FMCW) signal (24 GHz ± 40 MHz, modulation cycle: 2.5 ms), and show that the measured radiation patterns of a standard horn antenna agree well with the simulation results. We also demonstrate a proof-of-concept experiment that imitates a realistic situation of a bumper installed vehicle to show how the bumper alters the radiation patterns of the FMCW radar signal. The technique is based on photonics and enables measuring in the microwave to millimeter-wave range.

scholarly journals Near‐Field Terahertz Spectroscopy: Noninvasive Near‐Field Spectroscopy of Single Subwavelength Complementary Resonators (Laser Photonics Rev. 14(4)/2020)

2020 ◽  
Vol 14 (4) ◽  
pp. 2070022
Author(s):  
Lucy L. Hale ◽  
Janine Keller ◽  
Thomas Siday ◽  
Rodolfo I. Hermans ◽  
Johannes Haase ◽  
...  
Keyword(s):  
Terahertz Spectroscopy ◽  
Near Field ◽  
Field Spectroscopy

High-Precision Continuous-Wave Terahertz Spectroscopy Based on a Photomixing Technique for Identifying Pearls

2019 ◽  
Vol 73 (12) ◽  
pp. 1388-1393
Author(s):  
Chihoon Kim ◽  
Taeksoo Ji
Keyword(s):  
Optical Coherence Tomography ◽  
Fourier Transform ◽  
Ir Spectroscopy ◽  
Continuous Wave ◽  
Terahertz Spectroscopy ◽  
Thz Spectroscopy ◽  
Ft Ir ◽  
Thz Absorption ◽  
Ft Ir Spectroscopy ◽  
Cultured Pearls

We present the accurate terahertz spectra of between imitation and cultured pearls using continuous-wave terahertz (CW-THz) spectroscopy. Using Fourier transform infrared (FT-IR) spectroscopy and optical coherence tomography (OCT) measurements, cultured pearls can be distinguished from imitation pearls by observing distinct absorption peaks and discriminative boundaries. The THz absorption spectra up to 0.3 THz obtained from CW-THz spectroscopy show several absorption peaks at specific frequencies with the cultured pearls but no peaks with the imitation pearls, which results from the existence of the nacre polymorph of cultured pearls. Hence, it is expected that the CW-THz system proposed herein will be applicable to fast, nondestructive spectrum analysis including pearl identification.

scholarly journals High Power THz Generation from Sub-ps Bunches of Relativistic Electrons

2004 ◽  
Vol 850 ◽  
Author(s):  
S. Benson ◽  
D. R. Douglas ◽  
H. F. Dylla ◽  
J. Gubeli ◽  
K. Jordan ◽  
...  
Keyword(s):  
High Power ◽  
Near Field ◽  
Fourth Power ◽  
Thz Spectroscopy ◽  
Relativistic Electrons ◽  
Time Resolved ◽  
Picosecond Pulses ◽  
Coulomb Term ◽  
Joseph Larmor ◽  
New Generation

ABSTRACTWe describe a > 100 Watt broadband THz source that takes advantage of the relativistic enhancement of the radiation from accelerating electrons according to the formula assigned the name of Sir Joseph Larmor[1, 2]. This is in contrast to the typical 1 milliwatt sources available in a laboratory. Specifically, for relativistic electrons the emission is enhanced by the fourth power of the increase in mass. Thus for 100 MeV electrons, for which the mass increases by a factor of ∼ 200, the enhancement is > 109. The experiments use a new generation of light source called an energy recovery linac (ERL) [3], in which bunches of electrons circulate once, but in which their energy is recovered. In such a machine the electron bunches can be very much shorter than those, say, in storage rings or synchrotrons.The Jefferson Lab facility operates in new limits of emission from relativistic particles involving both multiparticle coherence and near-field emission in which the velocity (Coulomb) term in the classical electrodynamical theory becomes as important as the acceleration term (synchrotron radiation).The sub-picosecond pulses of light offer unique capabilities in 2 specific areas, namely time-resolved dynamics, and imaging. High resolution THz spectroscopy has recently revealed sharp vibrational modes for many materials including malignant tissue, proteins, DNA, pharmaceuticals and explosive materials. Energetically the THz range embraces superconducting bandgaps, and regions of intense interest in the understanding of systems in which correlated motions of electrons are important, such as colossal magneto-resistive and high-Tc materials. The very high power levels of the new source will allow non-linear effects to be observed as well as the creation of novel states of materials, including electric-field driven localization[4]. We will give examples of existing work in these areas and present opportunities afforded by the new source.

scholarly journals Diffuse terahertz spectroscopy in turbid media using a wavelet-based bimodality spectral analysis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mahmoud E. Khani ◽  
Omar B. Osman ◽  
M. Hassan Arbab
Keyword(s):  
Electromagnetic Scattering ◽  
Terahertz Spectroscopy ◽  
A Priori ◽  
Incident Beam ◽  
Mie Scattering ◽  
Turbid Media ◽  
Thz Spectroscopy ◽  
Receiver Operating Characteristic Curves ◽  
Wavelet Multiresolution Analysis ◽  
Priori Information

AbstractCurrent terahertz (THz) spectroscopy techniques only use the coherent light beam for spectral imaging. In the presence of electromagnetic scattering, however, the scattering-mitigated incoherent beams allow for flexible emitter-detector geometries, which enable applications such as seeing through turbid media. Despite this potential, THz spectroscopy using diffuse waves has not been demonstrated. The main obstacles are the very poor signal to noise ratios of the diffused fields and the resonance-like spectral artifacts due to multiple Mie scattering events that obscure the material absorption signatures. In this work, we demonstrate diffuse THz spectroscopy of a heterogeneous sample through turbid media using a novel technique based on the wavelet multiresolution analysis and the bimodality coefficient spectrum, which we define here for the first time using the skewness and kurtosis of the spectral images. The proposed method yields broadband and simultaneous material characterization at detection angles as high as 90° with respect to the incident beam. We determined the accuracy of the wavelet-based diffuse spectroscopy at oblique detection angles, by evaluating the area under the receiver operating characteristic curves, to be higher than 95%. This technique is agnostic to any a priori information on the spectral signatures of the sample materials or the characteristics of the scattering medium, and can be expanded for other broadband spectroscopic modalities.

scholarly journals Source Localization of EM Waves in the Near-Field of Spherical Antenna Array in the Presence of Unknown Mutual Coupling

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Oluwole John Famoriji ◽  
Thokozani Shongwe
Keyword(s):  
Antenna Array ◽  
Source Localization ◽  
Antenna Arrays ◽  
Mutual Coupling ◽  
Near Field ◽  
Ground Truth ◽  
Doa Estimation ◽  
Measured Data ◽  
Practical Applications ◽  
Spherical Antenna

To obtain an antenna array with isotropic radiation, spherical antenna array (SAA) is the right array configuration. The challenges of locating signals transmitted within the proximity of antenna array have been investigated considerably in the literature. However, near-field (NF) source localization of signals has hitherto not been investigated effectively using SAA in the presence of mutual coupling (MC). MC is another critical problem in antenna arrays. This paper presents an NF range and direction-of-arrival (DoA) estimation technique via the direction-independent and signal invariant spherical harmonics (SH) characteristics in the presence of mutual coupling. The energy of electromagnetic (EM) signal on the surface of SAA is captured successfully using a proposed pressure interpolation approach. The DoA estimation within the NF region is then calculated via the distribution of pressure. The direction-independent and signal invariant characteristics, which are SH features, are obtained using the DoA estimates in the NF region. We equally proposed a learning scheme that uses the source activity detection and convolutional neural network (CNN) to estimate the range of the NF source via the direction-independent and signal invariant features. Considering the MC problem and using the DoA estimates, an accurate spectrum peak in the multipath situation in conjunction with MC and a sharper spectrum peak from a unique MC structure and smoothing algorithms are obtained. For ground truth performance evaluation of the SH features within the context of NF localization, a numerical experiment is conducted and measured data were used for analysis to incorporate the MC and consequently computed the root mean square error (RMSE) of the source range and NF DoA estimate. The results obtained from numerical experiments and measured data indicate the validity and effectiveness of the proposed approach. In addition, these results are motivating enough for the deployment of the proposed method in practical applications.

scholarly journals Single-chip nanophotonic near-field imager

Optica ◽  
2019 ◽  
Vol 6 (10) ◽  
pp. 1255 ◽  
Author(s):  
Farshid Ashtiani ◽  
Angelina Risi ◽  
Firooz Aflatouni
Keyword(s):  
Near Field ◽  
Single Chip
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