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Journal articles on the topic 'THz scattering'

Author: Grafiati

Published: 10 December 2022

Last updated: 19 July 2025

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1

Wigmore, J. K., A. G. Kozorezov, Hamid bin Rani, M. Giltrow, H. Kraus, and B. M. Taele. "Scattering of THz phonons." Physica B: Condensed Matter 316-317 (May 2002): 589–91. http://dx.doi.org/10.1016/s0921-4526(02)00581-1.

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2

Dolganova, Irina N., Stanislav O. Yurchenko, Valeriy E. Karasik, and Vladimir P. Budak. "Peculiarity of Terahertz Waves Scattering." International Journal of High Speed Electronics and Systems 24, no. 01n02 (2015): 1520002. http://dx.doi.org/10.1142/s0129156415200025.

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Scattering of terahertz (THz) radiation is considered to be a significant problem for many applications, since it has often multiple character and is followed by interference effects. We present the computational results of THz propagation through scattering layers, obtained by using Monte Carlo simulation scheme of radiation transfer. Dense package of particles is considered for enhancing the influence of structure factor. Interference effects are shown to play an essential role for scattering phase function and scattering angular distribution of THz radiance.

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3

Jansen, Christian, Sebastian Priebe, Christoph Moller, et al. "Diffuse Scattering From Rough Surfaces in THz Communication Channels." IEEE Transactions on Terahertz Science and Technology 1, no. 2 (2011): 462–72. http://dx.doi.org/10.1109/tthz.2011.2153610.

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4

Li, Zhi. "Genetic Algorithm That Considers Scattering for THz Quantitative Analysis." IEEE Transactions on Terahertz Science and Technology 5, no. 6 (2015): 1062–67. http://dx.doi.org/10.1109/tthz.2015.2485218.

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5

Patzold, Martin, Matthias Kahl, Thomas Klinkert, et al. "Simulation and Data-Processing Framework for Hybrid Synthetic Aperture THz Systems Including THz-Scattering." IEEE Transactions on Terahertz Science and Technology 3, no. 5 (2013): 625–34. http://dx.doi.org/10.1109/tthz.2013.2274698.

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6

Wang, Suyun, and Kazuma Hiramatsu. "Experimental Analysis of Terahertz Wave Scattering Characteristics of Simulated Lunar Regolith Surface." Remote Sensing 16, no. 20 (2024): 3819. http://dx.doi.org/10.3390/rs16203819.

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This study investigates terahertz (THz) wave scattering from a simulated lunar regolith surface, with a focus on the Brewster feature, backscattering, and bistatic scattering within the 325 to 500 GHz range. We employed a generalized power-law spectrum to characterize surface roughness and fabricated Gaussian correlated surfaces from Durable Resin V2 using 3D printing technology. The complex dielectric permittivity of these materials was determined through THz time-domain spectroscopy (THz-TDS). Our experimental setup comprised a vector network analyzer (VNA) equipped with dual waveguide frequency extenders for the WR-2.2 band, transmitter and receiver modules, polarizing components, and a scattering chamber. We systematically analyzed the effects of root-mean-square (RMS) height, correlation length, dielectric constant, frequency, polarization, and observation angle on THz scattering. The findings highlight the significant impact of surface roughness on the Brewster angle shift, backscattering, and bistatic scattering. These insights are crucial for refining theoretical models and developing algorithms to retrieve physical parameters for lunar and other celestial explorations.

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7

Meng, Qingzhi, Qijing Lin, Zelin Wang, et al. "Numerical Investigation of GaN HEMT Terahertz Detection Model Considering Multiple Scattering Mechanisms." Nanomaterials 13, no. 4 (2023): 632. http://dx.doi.org/10.3390/nano13040632.

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GaN high-electron-mobility transistor (HEMT) terahertz (THz) detectors have been widely studied and applied in the past few decades. However, there are few reports about the influence of GaN/AlGaN heterostructure material properties on the detection model at present. In this paper, a response voltage model for a GaN HEMT THz detector that considers the carrier scattering in a GaN/AlGaN heterostructure is proposed. The phonon scattering, dislocation scattering, and interface roughness scattering mechanisms are taken into account in the classic THz response voltage model; furthermore, the influence of various material parameters on the response voltage is studied. In a low-temperature region, acoustic scattering plays an important role, and the response voltage drops with an increase in temperature. In a high temperature range, optical phonon scattering is the main scattering mechanism, and the detector operates in a non-resonant detection mode. With an increase in carrier surface density, the response voltage decreases and then increases due to piezoelectric scattering and optical phonon scattering. For dislocation and interface roughness scattering, the response voltage is inversely proportional to the dislocation density and root mean square roughness (RMS) but is positively related to lateral correlation length. Finally, a comparison between our model and the reported models shows that our proposed model is more accurate.

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8

PI Xiaoli, 皮小力, 高海林 GAO Hailin, and 郝东山 HAO Dongshan. "THz scattering property for a plasma sphere under Compton scattering." Optical Technique 41, no. 2 (2015): 115–18. http://dx.doi.org/10.3788/gxjs20154102.0115.

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9

Maissen, Curdin, Shu Chen, Elizaveta Nikulina, Alexander Govyadinov, and Rainer Hillenbrand. "Probes for ultra-sensitive THz nanoscopy." ACS Photonics 6, no. 5 (2019): 1279–88. https://doi.org/10.1021/acsphotonics.9b00324.

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Scattering-type scanning near-field microscopy (s-SNOM) at terahertz (THz) frequencies could become a highly valuable tool for studying a variety of phenomena of both fundamental and applied interest, including mobile carrier excitations or phase transitions in 2D materials or exotic conductors. Applications, however, are strongly challenged by the limited signal-to-noise ratio. One major reason is that standard atomic force microscope (AFM) tips – which have made s-SNOM a highly practical and rapidly emerging tool - provide weak scattering efficiencies at THz frequencies. Here we report a combined experimental and theoretical study of commercial and custom-made AFM tips of different apex diameter and length, in order to understand signal formation in THz s-SNOM and to provide insights for tip optimization. Contrary to common beliefs, we find that AFM tips with large (micrometer-scale) apex diameter can enhance s-SNOM signals by more than one order of magnitude, while still offering a spatial resolution of about 100 nm at a wavelength of λ = 119 μm. On the other hand, exploiting the increase of s-SNOM signals with tip length, we succeeded in sub-15 nm (<λ/8000) resolved THz imaging employing a tungsten tip with 6 nm apex radius. We explain our findings and provide novel insights into s-SNOM via rigorous numerical modeling of the near-field scattering process. Our findings will be of critical importance for pushing THz nanoscopy to its ultimate limits regarding sensitivity and spatial resolution.

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10

Wang, Suyun. "Terahertz Emission Modeling of Lunar Regolith." Remote Sensing 16, no. 21 (2024): 4037. http://dx.doi.org/10.3390/rs16214037.

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We investigate the terahertz (THz) scattering and emission properties of lunar regolith by modeling it as a random medium with rough top and bottom boundaries and a host medium situated beneath. The total scattering and emission arise from three sources: the rough boundaries, the volume, and the interactions between the boundaries and the volume. To account for these sources, we model their respective phase matrices and apply the matrix doubling approach to couple these phase matrices to compute the total emission. The model is then used to explore insights into lunar regolith scattering and emission processes. The simulations reveal that surface roughness is the primary contributor to total scattering, while dielectric contrasts between the volume and the boundaries dominate total emission. The THz emissivity is highly sensitive to the regolith dielectric constant, particularly its imaginary part, making it a promising alternative for identifying previously undetected water ice in the lunar polar regions. The THz emissivity model developed in this study can be readily applied to invert the surface parameters of lunar regolith using THz observations.

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11

WANG Youwei, MA Yihang, WANG Jiayi, et al. "Ultrafast Terahertz Scattering Scanning Near-field Optical Microscope." Acta Physica Sinica 74, no. 14 (2025): 0. https://doi.org/10.7498/aps.74.20250211.

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Terahertz (THz) time-domain spectroscopy and imaging techniques at the nanoscale are imperative for materials research and devices detection, among others. However, conventional far-field THz time-domain spectroscopy faces inherent diffraction limits, restricting applications requiring femtosecond temporal resolution and nanoscale spatial precision for carrier dynamics analysis. We present a scattering-type scanning near-field optical microscopy that overcomes these constraints by combining ultrafast THz time-domain spectroscopy with AFM. The utilization of the near-field interaction between the needle's tip and the sample's surface has been demonstrated to facilitate the study of semiconductor materials and devices with static THz spectroscopy at a lateral spatial resolution of ~60 nm. This, in turn, enables the acquisition of static THz conductivity distributions of the semiconductor materials. Additionally, it facilitates the acquisition of transient conductivity distributions of semiconductor materials and laser THz emission ultrafast via photoexcited transient carrier kinetic processes. This aspect provides substantial support for the study of the performance of materials and devices in nanometer spatial resolution, ultrafast time resolution, and THz spectroscopic imaging.The experimental results show that the system has a signal-to-noise ratio as high as 56.34 dB in the static THz time-domain spectral mode, and can effectively extract the fifth-order harmonic signals covering the 0.2-2.2 THz frequency band with a spatial resolution of up to ~60 nm. Carrier excitation and complexation processes in topological insulators have been successfully observed by optical pump-THz probe with a time resolution better than 100 fs. Imaging of SRAM samples by the system reveals differences in THz scattering intensity due to non-uniformity in doping concentration, validating its potential for nanoscale defect detection.This study not only provides an innovative means for the study of nanoscale electrical characterization of semiconductor materials and devices, but also opens up new avenues for the application of THz technology in interdisciplinary subjects such as nanophotonics and spintronics. In the future, the temporal and spatial resolution and detection efficiency of the system are expected to be further improved by integrating the superlens technology, optimizing the probe design and introducing deep learning algorithms.

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12

Liu, Sen, Xiaoliang Zhang, and Dawei Tang. "First-principles study of the thermal transport properties of superconducting NbN." E3S Web of Conferences 385 (2023): 03017. http://dx.doi.org/10.1051/e3sconf/202338503017.

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We investigate the thermal transport properties of NbN by considering three-phonon scattering (3ph), four-phonon scattering (4ph), electron-phonon (ep) scattering, and isotope (iso) scattering. By considering 4ph scattering, we find that 4ph scattering has less effect on the lattice thermal conductivity (κph) within 3-9 THz, while ep scattering has a greater effect on κph which is close to 3ph scattering in this frequency range. When the pressure is increased to 15 GPa, the κph by 148%, which is due to the decrease of the scattering phase space resulting in an increase of phonon relaxation time. We find that the κph of NbN is close to 100 W/mK, which is a potential high thermal conductivity material.

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13

Sears, V. F., E. C. Svensson, and B. M. Powell. "Phonon density of states in vanadium." Canadian Journal of Physics 73, no. 11-12 (1995): 726–34. http://dx.doi.org/10.1139/p95-107.

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The normalized phonon density of states g(v) of vanadium is accurately determined at room temperature (294 K) from the analysis of neutron inelastic-scattering data obtained using a triple-axis crystal spectrometer with a constant momentum transfer Q = 6.5 Å−1, (1 Å = 10−10 m) a constant scattered-neutron energy of 8.0 THz, and a variable incident-neutron energy. The energy transfer in the experiment varies from −1.9 to 10.0 THz, and the energy resolution (FWHM) is 0.35 THz at the elastic position. Necessary corrections are made for background scattering, multiple scattering, multiphonon scattering, absorption and self-shielding, and for the spatial inhomogeneity of the incident beam. The resulting g(v) distribution has an average statistical precision of about 3% and is characterized by peaks at 4.9 and 6.9 THz, which we attribute to transverse and longitudinal phonons, respectively, and by a cutoff at about 8.1 THz. The peaks in our g(v) distribution are much more clearly resolved than in any previous work on vanadium. We also see a small shoulder in g(v) in the region 2–3 THz, but it is far less pronounced than in some of the earlier experiments on vanadium. Below 2 THz we find that g(v) = av2, and the observed value of a leads to a Debye temperature that is in excellent agreement with that obtained from the measured elastic cosntants of vanadium at room temperature. A theoretical g(v) distribution calculated by Clark on the basis of a nearest- and next-nearest-neighbor central force model is in generally good agreement with our results although it differs in some details. In particular, Clark's theory predicts that the transverse peak should be slightly more intense than the longitudinal peak, whereas our experimental results indicate the opposite.

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14

Trukhin, Valeriy N., Nikolay N. Zinov’ev, Aleksandr V. Andrianov, et al. "Terahertz Coherent Scanning Probe Microscope." Siberian Journal of Physics 5, no. 4 (2010): 151–53. http://dx.doi.org/10.54362/1818-7919-2010-5-4-151-153.

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We present the terahertz (THz) scanning probe microscope which combines a THz coherent spectrometer and a scanning probe microscope. It detects forward-scattered radiation and employs harmonic signal demodulation to extract the signal of near-field contribution to scattering of THz electromagnetic waves

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15

Ning, Qianhao, Hongyuan Wang, Zhiqiang Yan, Xiang Liu, and Yinxi Lu. "Space-Based THz Radar Fly-Around Imaging Simulation for Space Targets Based on Improved Path Tracing." Remote Sensing 15, no. 16 (2023): 4010. http://dx.doi.org/10.3390/rs15164010.

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Aiming at the space target detection application of a space-based terahertz (THz) radar, according to the imaging mechanism of broadband THz radars, a THz radar imaging simulation method based on improved path tracing is proposed. Firstly, the characterization method of THz scattering characteristics based on Kirchhoff’s approximation method is introduced. The multi-parameter THz bidirectional reflectance distribution function (THz-BRDF) models of aluminum (Al), white-painted Al, and polyimide film at 0.215 THz are fitted according to the theoretical data, with fitting errors below 4%. Then, the THz radar imaging simulation method based on improved path tracing is presented in detail. The simulation method utilizes path tracing to simulate parallelized THz radar echo signal data, considering multi-path energy scattering based on the THz-BRDF model. Finally, we conducted THz radar imaging simulation experiments. The influences in the imaging process of different fly-around motions are analyzed, and a comparison experiment is conducted with the fast-physical optics (FPO) method. The comparative results indicate that the proposed method exhibits richer and more realistic features compared with the FPO method. The simulation experiments results demonstrate that the proposed method can provide a data source for ground algorithm testing of THz radars, particularly in evaluating the target detection and recognition algorithm based on deep learning, providing strong support for the application of space-based THz radars in the future.

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16

Liu, DongFeng, and GuoWei Chen. "Terahertz Absorption in Quantum Devices Based on Mg_xZn_1−xO/ZnO Quantum Well Structures." Journal of Nanoelectronics and Optoelectronics 17, no. 7 (2022): 1031–36. http://dx.doi.org/10.1166/jno.2022.3282.

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The energy level structures of MgxZn1−xO/ZnO/MgxZn1−xO quantum wells (QWs) with various geometrical structures and material compositions are obtained. Terahertz (THz) intersubband absorption can be realized and tunable with x in the range of 0.01~0.04 and well width in the range of 5~13 nm. Electron scattering such as piezoelectric acoustic phonon (PAP), polar optical phonon (POP), interface roughness (IFR), and random alloy (RAS) scattering are included in the calculations to analyze the linewidth broadening. Increasing the Mg composition or decreasing the well width can obtain high-frequency THz intersubband absorption, in which case IFR is found to be the physical mechanism that makes the linewidth broaden. On the other hand, the influence difference of PAP scattering for the lower Mg composition, which may be caused by the different electro-mechanical coupling coefficients (EMCC), is obviously larger than that for the higher Mg composition, meaning that the accurate value of EMCC is much more important for the THz intersubband absorption in MgxZn1−xO/ZnO/MgxZn1−xO QWs with a smaller x. The findings are helpful in the design of THz detector devices.

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17

Li, Zhi, Weidong Chen, Feiyu Lian, Hongyi Ge, and Aihong Guan. "Wavelength Selection Method Based on Differential Evolution for Precise Quantitative Analysis Using Terahertz Time-Domain Spectroscopy." Applied Spectroscopy 71, no. 12 (2017): 2653–60. http://dx.doi.org/10.1177/0003702817722367.

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Quantitative analysis of component mixtures is an important application of terahertz time-domain spectroscopy (THz-TDS) and has attracted broad interest in recent research. Although the accuracy of quantitative analysis using THz-TDS is affected by a host of factors, wavelength selection from the sample’s THz absorption spectrum is the most crucial component. The raw spectrum consists of signals from the sample and scattering and other random disturbances that can critically influence the quantitative accuracy. For precise quantitative analysis using THz-TDS, the signal from the sample needs to be retained while the scattering and other noise sources are eliminated. In this paper, a novel wavelength selection method based on differential evolution (DE) is investigated. By performing quantitative experiments on a series of binary amino acid mixtures using THz-TDS, we demonstrate the efficacy of the DE-based wavelength selection method, which yields an error rate below 5%.

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18

Nakagawa, Hiroshi, and Naoki Yamamoto. "Incoherent Neutron Scattering and Terahertz Time-Domain Spectroscopy on Protein and Hydration Water." Life 13, no. 2 (2023): 318. http://dx.doi.org/10.3390/life13020318.

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Incoherent inelastic and quasi-elastic neutron scattering (INS) and terahertz time-domain spectroscopy (THz-TDS) are spectroscopy methods that directly detect molecular dynamics, with an overlap in the measured energy regions of each method. Due to the different characteristics of their probes (i.e., neutron and light), the information obtained and the sample conditions suitable for each method differ. In this review, we introduce the differences in the quantum beam properties of the two methods and their associated advantages and disadvantages in molecular spectroscopy. Neutrons are scattered via interaction with nuclei; one characteristic of neutron scattering is a large incoherent scattering cross-section of a hydrogen atom. INS records the auto-correlation functions of atomic positions. By using the difference in neutron scattering cross-sections of isotopes in multi-component systems, some molecules can be selectively observed. In contrast, THz-TDS observes the cross-correlation function of dipole moments. In water-containing biomolecular samples, the absorption of water molecules is particularly large. While INS requires large-scale experimental facilities, such as accelerators and nuclear reactors, THz-TDS can be performed at the laboratory level. In the analysis of water molecule dynamics, INS is primarily sensitive to translational diffusion motion, while THz-TDS observes rotational motion in the spectrum. The two techniques are complementary in many respects, and a combination of the two is very useful in analyzing the dynamics of biomolecules and hydration water.

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19

Wang Rongrong, 王蓉蓉, 吴振森 Wu Zhensen, 张艳艳 Zhang Yanyan, 王明军 Wang Mingjun, and 巩蕾 Gong Lei. "Multiple scattering characteristics of THz wave in fog." High Power Laser and Particle Beams 26, no. 11 (2014): 113101. http://dx.doi.org/10.3788/hplpb20142611.113101.

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20

Kaushik, Mayank, Brian W. H. Ng, Bernd M. Fischer, and Derek Abbott. "Reduction of Scattering Effects in THz-TDS Signals." IEEE Photonics Technology Letters 24, no. 2 (2012): 155–57. http://dx.doi.org/10.1109/lpt.2011.2174980.

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21

Eng, Lukas M., Frederik Kuschewski, Jonathan Döring, et al. "Near-Field THz Nanoscopy with Novel Accelerator-Based Photon Sources." Proceedings 26, no. 1 (2019): 1. http://dx.doi.org/10.3390/proceedings2019026001.

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22

Huang, Jie, Jie Wang, Linghui Guo, et al. "Organelle Imaging with Terahertz Scattering-Type Scanning Near-Field Microscope." International Journal of Molecular Sciences 24, no. 17 (2023): 13630. http://dx.doi.org/10.3390/ijms241713630.

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Organelles play core roles in living beings, especially in internal cellular actions, but the hidden information inside the cell is difficult to extract in a label-free manner. In recent years, terahertz (THz) imaging has attracted much attention because of its penetration depth in nonpolar and non-metallic materials and label-free, non-invasive and non-ionizing ability to obtain the interior information of bio-samples. However, the low spatial resolution of traditional far-field THz imaging systems and the weak dielectric contrast of biological samples hinder the application of this technology in the biological field. In this paper, we used an advanced THz scattering near-field imaging method for detecting chloroplasts on gold substrate with nano-flatness combined with an image processing method to remove the background noise and successfully obtained the subcellular-grade internal reticular structure from an Arabidopsis chloroplast THz image. In contrast, little inner information could be observed in the tea chloroplast in similar THz images. Further, transmission electron microscopy (TEM) and mass spectroscopy (MS) were also used to detect structural and chemical differences inside the chloroplasts of Arabidopsis and tea plants. The preliminary results suggested that the interspecific different THz information is related to the internal spatial structures of chloroplasts and metabolite differences among species. Therefore, this method could open a new way to study the structure of individual organelles.

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23

Hernando Abad, Eduardo Hernando, Frédéric Bouyer, Laroussi Chaabane, Alan Zerrouki, Jérémie Margueritat, and Lucien Saviot. "Sub-THz Vibrational Dynamics in Ordered Mesoporous Silica Nanoparticles." Nanomaterials 13, no. 14 (2023): 2078. http://dx.doi.org/10.3390/nano13142078.

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The vibrational dynamics in the sub-THz range of mesoporous silica nanoparticles (MSNs) having ordered cylindrical mesopores was investigated. MCM-41 and SBA-15 particles were synthesized, and their structure was determined using scanning electron microscopy (SEM), low-angle X-ray diffraction (XRD), N2 physisorption analyses, and Raman scattering. Brillouin scattering measurements are reported and enabled determining the stiffness of the silica walls (speed of sound) using finite element calculations for the ordered mesoporous structure. The relevance of this approach is discussed based on the comparison between the numerical and experimental results and previous works reported in the literature.

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24

Piesiewicz, Radoslaw, Christian Jansen, Daniel Mittleman, Thomas Kleine-Ostmann, Martin Koch, and Thomas Kurner. "Scattering Analysis for the Modeling of THz Communication Systems." IEEE Transactions on Antennas and Propagation 55, no. 11 (2007): 3002–9. http://dx.doi.org/10.1109/tap.2007.908559.

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25

Fan Changkun, 樊长坤, 李琦 Li Qi, 赵永蓬 Zhao Yongpeng, and 陈德应 Chen Deying. "Measurement of 2.52 THz back scattering in different roughness paraboloid." Infrared and Laser Engineering 46, no. 11 (2017): 1125005. http://dx.doi.org/10.3788/irla201746.1125005.

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26

Taele, B. M., A. G. Kozorezov, Hamid Bin Rani, and J. K. Wigmore. "Point defect scattering of THz phonons in sapphire determined by heat pulse back-scattering." Radiation Effects and Defects in Solids 155, no. 1-4 (2001): 339–44. http://dx.doi.org/10.1080/10420150108214134.

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27

Ike, Yuji, Yuichi Seshimo, and Seiji Kojima. "Crystallization and vitrification of cryoprotectants studied by Raman scattering, Brillouin scattering and THz-TDS." Journal of Molecular Structure 924-926 (April 2009): 127–30. http://dx.doi.org/10.1016/j.molstruc.2009.01.028.

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28

Guiana, Brian, and Ata Zadehgol. "Characterizing THz Scattering Loss in Nano-Scale SOI Waveguides Exhibiting Stochastic Surface Roughness with Exponential Autocorrelation." Electronics 11, no. 3 (2022): 307. http://dx.doi.org/10.3390/electronics11030307.

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Electromagnetic (EM) scattering may be a significant source of degradation in signal and power integrity of high-contrast silicon-on-insulator (SOI) nano-scale interconnects, such as opto-electronic or optical interconnects operating at 100 s of THz where two-dimensional (2D) analytical models of dielectric slab waveguides are often used to approximate scattering loss. In this work, a formulation is presented to relate the scattering (propagation) loss to the scattering parameters (S-parameters) for the smooth waveguide; the results are correlated with results from the finite-difference time-domain (FDTD) method in 2D space. We propose a normalization factor to the previous 2D analytical formulation for the stochastic scattering loss based on physical parameters of waveguides exhibiting random surface roughness under the exponential autocorrelation function (ACF), and validate the results by comparing against numerical experiments via the 2D FDTD method, through simulation of hundreds of rough waveguides; additionally, results are compared to other 2D analytical and previous 3D experimental results. The FDTD environment is described and validated by comparing results of the smooth waveguide against analytical solutions for wave impedance, propagation constant, and S-parameters. Results show that the FDTD model is in agreement with the analytical solution for the smooth waveguide and is a reasonable approximation of the stochastic scattering loss for the rough waveguide.

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29

Алексеев, П. А., Б. Р. Бородин, И. А. Мустафин та ін. "Терагерцевый ближнепольный отклик в лентах графена". Письма в журнал технической физики 46, № 15 (2020): 29. http://dx.doi.org/10.21883/pjtf.2020.15.49745.18256.

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The experimental results of scattering and near-field interaction of a terahertz electromagnetic field with graphene ribbons near a metal probe of an atomic force microscope are reported. The amplification of a near-field terahertz scattering in ribbons is shown in comparison with unstructured graphene. The appearance of resonance peaks in the range 0.2–1.6 THz in the scattering spectra of terahertz radiation on graphene ribbons in the presence of a probe was detected, which is possibly due to the interaction of radiation with plasmons in the ribbons.

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Sun, Kaixiang, Jiukai Fang, Yanpeng Shi, et al. "Terahertz Refractive Index Sensor Based on Enhanced Extraordinary Optical Transmission." Crystals 12, no. 11 (2022): 1616. http://dx.doi.org/10.3390/cryst12111616.

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This paper presents a structure for refractive index sensors in the terahertz (THz) band. The THZ sensor is studied in simulation, utilizing the strong local electromagnetic field intensity produced by the enhanced extraordinary optical transmission. Depending on the different sensing positions of the sensor, their sensing basis is also different, such as Mie scattering, surface plasmon polaritons, etc. The sensing sensitivity based on Mie scattering can reach 51.56 GHz/RIU; meanwhile the sensing sensitivity based on surface plasmon polaritons is only 5.13 GHz/RIU. The sensor can also detect the thickness of the analyte, with the lowest detectable height of 0.2 µm. Additionally, we find that the sensitivity can be increased by replacing the silicon particle with the analyte.

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31

Koda, Shota, Tatsuya Mori, and Seiji Kojima. "Broadband Terahertz Time-Domain Spectroscopy and Low-Frequency Raman Scattering of Propylene Glycol." International Letters of Chemistry, Physics and Astronomy 62 (November 2015): 15–20. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.62.15.

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Two different THz-TDS systems were used for the accurate study of broadband terahertz dynamics between 0.1 and 5.0 THz. These systems enabled to observe the whole spectral structure of the broad peak at 1.5 THz in propylene glycol. At high-frequency side of the broad peak in the dielectric spectrum, the small shoulder peak at 3.6 THz was also observed. It is assigned to the inter-molecular vibration, which is supported by the precedent report and the Gaussian calculation. In contrast, the low-frequency side of the broad peak includes the contribution of the relaxation processes which exist in the MHz and GHz region. Furthermore, we compared the dielectric spectrum with the Raman spectrum and concluded that the mode at 3.6 THz is IR active while Raman inactive.

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32

Koda, Shota, Tatsuya Mori, and Seiji Kojima. "Broadband Terahertz Time-Domain Spectroscopy and Low-Frequency Raman Scattering of Propylene Glycol." International Letters of Chemistry, Physics and Astronomy 62 (November 27, 2015): 15–20. http://dx.doi.org/10.56431/p-yfjq9w.

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Two different THz-TDS systems were used for the accurate study of broadband terahertz dynamics between 0.1 and 5.0 THz. These systems enabled to observe the whole spectral structure of the broad peak at 1.5 THz in propylene glycol. At high-frequency side of the broad peak in the dielectric spectrum, the small shoulder peak at 3.6 THz was also observed. It is assigned to the inter-molecular vibration, which is supported by the precedent report and the Gaussian calculation. In contrast, the low-frequency side of the broad peak includes the contribution of the relaxation processes which exist in the MHz and GHz region. Furthermore, we compared the dielectric spectrum with the Raman spectrum and concluded that the mode at 3.6 THz is IR active while Raman inactive.

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33

HYART, TIMO, KIRILL N. ALEKSEEV, AHTI LEPPÄNEN, and ERKKI V. THUNEBERG. "TERAHERTZ BLOCH OSCILLATOR WITH SUPPRESSED ELECTRIC DOMAINS: EFFECT OF ELASTIC SCATTERING." International Journal of Modern Physics B 23, no. 20n21 (2009): 4459–72. http://dx.doi.org/10.1142/s0217979209063596.

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We theoretically consider the amplification of THz radiation in a superlattice Bloch oscillator. The main dilemma in the realization of THz Bloch oscillator is finding operational conditions which allow simultaneously to achieve gain at THz frequencies and to avoid destructive space-charge instabilities. A possible solution to this dilemma is the extended Limited Space-Charge Accumulation scheme of Kroemer (H. Kroemer, cond-mat/0009311). Within the semiclassical miniband transport approach we extend its range of applicability by considering a difference in the relaxation times for electron velocity and electron energy. The kinetics of electrons and fields establishing a stationary signal in the oscillator is also discussed.

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34

Hario P, Fakhriy, Adhi Susanto, I. Wayan Mustika, Sevia M Idrus, and Sholeh Hadi P. "Dithering Analysis in an Orthogonal Frequency Division Multiplexing-Radio over Fiber Link." International Journal of Electrical and Computer Engineering (IJECE) 6, no. 3 (2016): 1112. http://dx.doi.org/10.11591/ijece.v6i3.9684.

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Nonlinearity is one major problem broadband communication faced on utilizing the high capacity of optical fibers. That is due to scattering phenomenon, which results in the deviations of wavelengths and energies. The dithering method is applied in the attempt to reduce those scatterings. In this paper, we propose the performance of a dithering technique based new system OFDM-RoF using two modulator scheme and coherent detection to alleviate the characteristics nonlinearity applied on the system. The dithering technique inputs signal externally to the signal processing systems to eliminate the effects of nonlinearity. Here, we report the performance of a dithering technique based on the OFDM-RoF, the results our experiment showed that the applied dithering with 16 QAM modulation can make the system more reliable and increases the power level 1.55% with 193.1 THz, 2% with 100 THz and 1.99% ~ 200 THz, the best condition are with f<sub>d</sub> &lt; f<sub>c</sub>. However, all condition close proximity in the parameters OLP (optical launch power), BER and SER measurement. The result demonstrated a high efficiency and good power in which the OLP operated 6.396 dBm / 4.361 E-3 W~fd 200 THz, 3.578 dBm / 2.279 E-3 W~fd 193.1 THz and 6.420 dBm / 4.3384 E-3 W~100 THz. The best BER value is achieved at 0.33 and SER 0.78 at 5 km~f<sub>d</sub> 100 THz, 0.33 and 0.768 for 10 km~fd 193.1 THz, 0.478 and 0.92 for 50 km~fd 193.1 THz.

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35

Hario P, Fakhriy, Adhi Susanto, I. Wayan Mustika, Sevia M Idrus, and Sholeh Hadi P. "Dithering Analysis in an Orthogonal Frequency Division Multiplexing-Radio over Fiber Link." International Journal of Electrical and Computer Engineering (IJECE) 6, no. 3 (2016): 1112. http://dx.doi.org/10.11591/ijece.v6i3.pp1112-1121.

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Nonlinearity is one major problem broadband communication faced on utilizing the high capacity of optical fibers. That is due to scattering phenomenon, which results in the deviations of wavelengths and energies. The dithering method is applied in the attempt to reduce those scatterings. In this paper, we propose the performance of a dithering technique based new system OFDM-RoF using two modulator scheme and coherent detection to alleviate the characteristics nonlinearity applied on the system. The dithering technique inputs signal externally to the signal processing systems to eliminate the effects of nonlinearity. Here, we report the performance of a dithering technique based on the OFDM-RoF, the results our experiment showed that the applied dithering with 16 QAM modulation can make the system more reliable and increases the power level 1.55% with 193.1 THz, 2% with 100 THz and 1.99% ~ 200 THz, the best condition are with f<sub>d</sub> &lt; f<sub>c</sub>. However, all condition close proximity in the parameters OLP (optical launch power), BER and SER measurement. The result demonstrated a high efficiency and good power in which the OLP operated 6.396 dBm / 4.361 E-3 W~fd 200 THz, 3.578 dBm / 2.279 E-3 W~fd 193.1 THz and 6.420 dBm / 4.3384 E-3 W~100 THz. The best BER value is achieved at 0.33 and SER 0.78 at 5 km~f<sub>d</sub> 100 THz, 0.33 and 0.768 for 10 km~fd 193.1 THz, 0.478 and 0.92 for 50 km~fd 193.1 THz.

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36

LI Yingle, 李应乐, 李瑾 LI Jin, 王明军 WANG Mingjun, and 董群峰 DONG Qunfeng. "THz Scattering Property for a Magnetized Cold Plasma Sphere." ACTA PHOTONICA SINICA 41, no. 5 (2012): 619–22. http://dx.doi.org/10.3788/gzxb20124105.0619.

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37

Chen Min, Xiao Ti-Qiao, and Xu Hong-Jie. "Propagation of ultrashort THz pulse in random scattering media." Acta Physica Sinica 52, no. 11 (2003): 2807. http://dx.doi.org/10.7498/aps.52.2807.

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38

Bandyopadhyay, Aparajita, Amartya Sengupta, Robert B. Barat, et al. "Effects of Scattering on THz Spectra of Granular Solids." International Journal of Infrared and Millimeter Waves 28, no. 11 (2007): 969–78. http://dx.doi.org/10.1007/s10762-007-9276-y.

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39

Sabery, Shahrzad Minooee, Aleksandr Bystrov, Miguel Navarro-Cía, Peter Gardner, and Marina Gashinova. "Study of Low Terahertz Radar Signal Backscattering for Surface Identification." Sensors 21, no. 9 (2021): 2954. http://dx.doi.org/10.3390/s21092954.

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This study explores the scattering of signals within the mm and low Terahertz frequency range, represented by frequencies 79 GHz, 150 GHz, 300 GHz, and 670 GHz, from surfaces with different roughness, to demonstrate advantages of low THz radar for surface discrimination for automotive sensing. The responses of four test surfaces of different roughness were measured and their normalized radar cross sections were estimated as a function of grazing angle and polarization. The Fraunhofer criterion was used as a guideline for determining the type of backscattering (specular and diffuse). The proposed experimental technique provides high accuracy of backscattering coefficient measurement depending on the frequency of the signal, polarization, and grazing angle. An empirical scattering model was used to provide a reference. To compare theoretical and experimental results of the signal scattering on test surfaces, the permittivity of sandpaper has been measured using time-domain spectroscopy. It was shown that the empirical methods for diffuse radar signal scattering developed for lower radar frequencies can be extended for the low THz range with sufficient accuracy. The results obtained will provide reference information for creating remote surface identification systems for automotive use, which will be of particular advantage in surface classification, object classification, and path determination in autonomous automotive vehicle operation.

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40

Shapoval, Olga V., Juan Sebastian Gomez-Diaz, Julien Perruisseau-Carrier, Juan R. Mosig, and Alexander I. Nosich. "Integral Equation Analysis of Plane Wave Scattering by Coplanar Graphene-Strip Gratings in the THz Range." IEEE Transactions on Terahertz Science and Technology 3, no. 5 (2013): 666–74. http://dx.doi.org/10.1109/tthz.2013.2263805.

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41

Fan Changkun, 樊长坤, 李琦 Li Qi, 赵永蓬 Zhao Yongpeng, and 陈德应 Chen Deying. "Measurement for 2.52 THz Back Scattering Intensity of Rectangular Aluminum Plate." Chinese Journal of Lasers 44, no. 12 (2017): 1214001. http://dx.doi.org/10.3788/cjl201744.1214001.

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42

Hussein, A. Abdulnabi, Abdulhussain Shuriji Mushreq, and Ahmed Sadiq. "UWB THz plasmonic microstrip antenna based on graphene." TELKOMNIKA Telecommunication, Computing, Electronics and Control 18, no. 1 (2020): 30–36. https://doi.org/10.12928/TELKOMNIKA.v18i1.13153.

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This paper proposes design and investigates of graphene based plasmonic microstrip antenna for terahertz high speed communication and application systems 0.1-20 THz. The proposed antenna structure composed of graphenebased rectangular patch and transmission line mounted on a grounded silicone dioxide substrate. SPP (Surface Plasmon Polariton) waves that appear in graphene at THz band is analyzed. The proposed antenna simulation was done by using numerical method CST program. The simulation results show the scattering parameter S11 less than -10 dB at frequency band (0.1-20) THz. Also, the presented antenna system has a good gain along the frequency band.

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Ma, Duoxuan, Jie Zhao, Dayong Wang, et al. "Full-Field Super-Resolution Terahertz Imaging Based on Rotating Coherent Scattering Microscopy." Applied Sciences 13, no. 2 (2023): 982. http://dx.doi.org/10.3390/app13020982.

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For decades, terahertz (THz) microscopic imaging has been limited by the resolution of the system due to the larger wavelength, the power of the source, and the equivalent noise power of the detector, so a lot of research has focused on single-point scanning imaging. With the development of hardware, full-field THz imaging based on high-power continuous-wave THz sources have been developed such as the direct intensity imaging method and lensless coherent imaging. In particular, the THz direct intensity imaging method requires no complicated computational reconstruction, while the high resolution, as a key issue, still needs to be improved. In this paper, the rotating coherent scattering microscopy was applied to THz imaging for the first time. Here, we designed and fabricated a hemisphere lens with high-resistance silicon. The tilted hemisphere lens transformed the incident divergent beam into a plane wave, and the total internal reflection occurred in the planar surface within the hemispherical lens, and generated evanescent waves in the rare medium. At the same time, the sample was placed very close to the plane of the hemispherical lens, so that the sample was illuminated by the evanescent waves. The scattered waves carried high frequency information to the far field, and thus through an objective, the super-resolution imaging was achieved along a single direction. Then, the hemispherical lens was rotated to obtain coherent scattering microscopic images under different evanescent wave illumination angles. Finally, the full-field super-resolution imaging results were obtained through incoherent superposition.

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44

Li, Zhongyang, Lian Tan, Yongjun Li, et al. "Simultaneous Generation of Two Pairs of Stokes and Terahertz Waves from Coupled Optical Parametric Oscillations with Quasi-Phase-Matching." Crystals 8, no. 8 (2018): 323. http://dx.doi.org/10.3390/cryst8080323.

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We present a theoretical investigation on simultaneous generation of two pairs of Stokes and terahertz (THz) waves from coupled optical parametric oscillations (OPOs) with a quasi-phase-matching (QPM) scheme. The two pairs of Stokes and THz waves are generated by stimulated polariton scattering (SPS) from periodically-inverted GaP. By analyzing the QPM conditions of coupled OPOs we find that the two THz waves with any frequency below the transverse optical (TO) mode frequency of GaP can be simultaneously generated with a suitable pump wavelength. We calculate the photon flux densities of the two THz waves by solving the coupled wave equations. The calculation results indicate that the two THz waves can be efficiently generated with high pump intensities, particularly in lower THz frequency band.

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45

Vereshchagin, Konstantin A., Alexey K. Vereshchagin, Vyacheslav B. Morozov, and Vladimir G. Tunkin. "Cascaded Stimulated Polariton Scattering in a Single-Pass KTP Crystal under Picosecond Pumping." Photonics 10, no. 12 (2023): 1355. http://dx.doi.org/10.3390/photonics10121355.

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Cascaded stimulated polariton scattering (SPS) under powerful picosecond pumping of 532 nm wavelength was investigated in a single pass of a KTP (KTiOPO4) crystal. Under ordinary polarization of the pump wave (relatively XOZ-plane) parametric scattering in the KTP crystal was observed. By rotation of the pump wave polarization (from ordinary to extraordinary), this scattering gradually transforms into polariton scattering. Polariton signal components (spots) with gaps between them were registered at external angles of ~2° between the neighboring spots. Five polariton signal components were detected above the pump beam, with a frequency difference between neighboring cascaded components of ~188 cm−1 (5.64 THz). The wavelength of each next component increased regularly with the angle between this component and the pump wave, so this regular sequence of polariton signal components can be regarded as a cascaded SPS.

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46

Kang, Chul, Gyuseok Lee, Woo-Jung Lee, et al. "Terahertz Emission and Ultrafast Carrier Dynamics of Ar-Ion Implanted Cu(In,Ga)Se2 Thin Films." Crystals 11, no. 4 (2021): 411. http://dx.doi.org/10.3390/cryst11040411.

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We investigated THz emission from Ar-ion-implanted Cu(In,Ga)Se2 (CIGS) films. THz radiation from the CIGS films increases as the density of implanted Ar ions increases. This is because Ar ions contribute to an increase in the surface surge current density. The effect of Ar-ion implantation on the carrier dynamics of CIGS films was also investigated using optical pump THz probe spectroscopy. The fitted results imply that implanted Ar ions increase the charge transition of intra-and carrier–carrier scattering lifetimes and decrease the bandgap transition lifetime.

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47

Kambara, Ohki, and Keisuke Tominaga. "Structural fluctuation of proteins revealed by terahertz time-domain spectroscopy." Spectroscopy 24, no. 1-2 (2010): 149–52. http://dx.doi.org/10.1155/2010/391586.

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We have measured spectra of the absorption coefficient and refractive index of hen egg white lysozyme in the wavenumber region from 7 cm–1to 50 cm–1by terahertz (THz) time-domain spectroscopy. From comparison with the results of the inelastic neutron scattering experiment it is concluded that analysis of the THz spectra provides information on the vibrational density of states. We studied temperature dependence of the THz spectra as well as hydration effect on them to discuss structural fluctuation of the protein. We observed dynamical transition at around 210 K for lysozyme.

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48

Lima, Thamires A., Vitor H. Paschoal, Rafael S. Freitas, et al. "An inelastic neutron scattering, Raman, far-infrared, and molecular dynamics study of the intermolecular dynamics of two ionic liquids." Physical Chemistry Chemical Physics 22, no. 16 (2020): 9074–85. http://dx.doi.org/10.1039/d0cp00374c.

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The THz dynamics of ionic liquids based on tetraalkylammonium cations were investigated by a combined usage of inelastic neutron scattering (INS), Raman, and far-infrared (FIR) spectroscopies and the power spectrum calculated by molecular dynamics (MD) simulations.

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Dadrasnia, Ehsan, Sujitha Puthukodan, Vinod V. K. Thalakkatukalathil, et al. "Sub-THz Characterisation of Monolayer Graphene." Journal of Spectroscopy 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/601059.

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We explore the optical and electrical characteristics of monolayer graphene by using pulsed optoelectronic terahertz time-domain spectroscopy in the frequency range of 325–500 GHz based on fast direct measurements of phase and amplitude. We also show that these parameters can, however, be measured with higher resolution using a free space continuous wave measurement technique associated with a vector network analyzer that offers a good dynamic range. All the scattering parameters (both magnitude and phase) are measured simultaneously. The Nicholson-Ross-Weir method is implemented to extract the monolayer graphene parameters at the aforementioned frequency range.

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50

Peng, Zhaomin, Dehai Zhang, Shuqi Ge, and Jin Meng. "Quantitative Modeling of Near-Field Interactions in Terahertz Near-Field Microscopy." Applied Sciences 13, no. 6 (2023): 3400. http://dx.doi.org/10.3390/app13063400.

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Terahertz scattering-scanning near-field optical microscopy (THz s-SNOM), combining the best features of terahertz technology and s-SNOM technology, has shown unique advantages in various applications. Consequently, building a model to characterize near-field interactions and investigate practical issues has become a popular topic in THz s-SNOM research. In this study, a finite element model (FEM) is proposed to quantify the near-field interactions, and to investigate the edge effect and antenna effect in THz s-SNOM. Our results indicate that the proposed model can give us a better understanding of the near-field interactions and direct the parameter design of the probe for THz s-SNOM.

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