Готові списки джерел за темами / Terahertz; scattering

Добірка наукової літератури з теми "Terahertz; scattering"

Автор: Grafiati

Опубліковано: 10 грудня 2022

Оновлено: 28 січня 2023

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Статті в журналах з теми "Terahertz; scattering"

Wu, Yu Deng, and Guang Jun Ren. "Study of Enhanced Surface Raman Scattering on Nano-Particle in Terahertz Range." Advanced Materials Research 977 (June 2014): 108–11. http://dx.doi.org/10.4028/www.scientific.net/amr.977.108.

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Researched the surface-enhanced Raman scattering on nanoparticle in terahertz range, and proved the existence of the same phenomenon-Raman enhancements in the terahertz band. By studying the electromagnetic enhancement principle of surface-enhanced Raman scattering, proposed to using finite difference time-domain to simulate the surface-enhanced Raman scattering of nanoparticles in the terahertz irradiated. Simulation results show that the FDTD method can effectively simulate the scattering of nanoparticles in terahertz band, resulting in surface-enhanced Raman scattering from the visible and infrared bands extended to the terahertz band, and the result provides basis for terahertz waves and surface-enhanced Raman scattering the combined application.

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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 (March 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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Алексеев, П. А., Б. Р. Бородин, И. А. Мустафин, А. В. Зубов, С. П. Лебедев, А. А. Лебедев та В. Н. Трухин. "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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Kaushik, Mayank, Brian W. H. Ng, Bernd M. Fischer, and Derek Abbott. "Terahertz scattering by dense media." Applied Physics Letters 100, no. 24 (June 11, 2012): 241110. http://dx.doi.org/10.1063/1.4720078.

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Zurk, Lisa M., Brian Orlowski, Dale P. Winebrenner, Eric I. Thorsos, Megan R. Leahy-Hoppa, and L. Michael Hayden. "Terahertz scattering from granular material." Journal of the Optical Society of America B 24, no. 9 (August 17, 2007): 2238. http://dx.doi.org/10.1364/josab.24.002238.

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He, Xiaoyong, Fangting Lin, Feng Liu, and Hao Zhang. "Investigation of Phonon Scattering on the Tunable Mechanisms of Terahertz Graphene Metamaterials." Nanomaterials 10, no. 1 (December 23, 2019): 39. http://dx.doi.org/10.3390/nano10010039.

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The influences of different kinds of phonon scatterings (i.e., acoustic (AC) phonon, impurity, and longitudinal optical (LO) phonon scatterings) on the tunable propagation properties of graphene metamaterials structures have been investigated, also including the effects of graphene pattern structures, Fermi levels, and operation frequencies. The results manifested that, at room temperature, AC phonon scattering dominated, while with the increase in temperature, the LO phonon scattering increased significantly and played a dominate role if temperature goes beyond 600 K. Due to the phonon scatterings, the resonant properties of the graphene metamaterial structure indicated an optimum value (about 0.5–0.8 eV) with the increase in Fermi level, which were different from the existing results. The results are very helpful to understand the tunable mechanisms of graphene functional devices, sensors, modulators, and antennas.

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YANG, Yang, Jian-Quan YAO, Jing-Shui ZHANG, and Li WANG. "Terahertz scattering on rough copper surface." Journal of Infrared and Millimeter Waves 32, no. 1 (2013): 36. http://dx.doi.org/10.3724/sp.j.1010.2013.00036.

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Png, Gretel M., Christophe Fumeaux, Mark R. Stringer, Robert E. Miles, and Derek Abbott. "Terahertz scattering by subwavelength cylindrical arrays." Optics Express 19, no. 11 (May 9, 2011): 10138. http://dx.doi.org/10.1364/oe.19.010138.

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Born, Philip, Nick Rothbart, Matthias Sperl, and Heinz-Wilhelm Hübers. "Granular structure determined by terahertz scattering." EPL (Europhysics Letters) 106, no. 4 (May 1, 2014): 48006. http://dx.doi.org/10.1209/0295-5075/106/48006.

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Amarasinghe, Yasith, Wei Zhang, Rui Zhang, Daniel M. Mittleman, and Jianjun Ma. "Scattering of Terahertz Waves by Snow." Journal of Infrared, Millimeter, and Terahertz Waves 41, no. 2 (December 3, 2019): 215–24. http://dx.doi.org/10.1007/s10762-019-00647-4.

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Дисертації з теми "Terahertz; scattering"

Nam, Kyung Moon. "Modeling Terahertz Diffuse Scattering from Granular Media Using Radiative Transfer Theory." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/380.

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Terahertz (THz) spectroscopy can potentially be used to probe and characterize inhomogeneous materials, however spectroscopic identification of such materials from spectral features of diffuse returns is a relatively underdeveloped area of study. In this thesis, diffuse THz scattering from granular media is modeled by applying radiative transfer (RT) theory for the first time in THz sensing. Both classical RT theory and dense media radiative transfer (DMRT) theory based on the quasi-crystalline approximation (QCA) are used to calculate diffuse scattered intensity. The numerical solutions of the vector radiative transfer equations (VRTE) were coded and calculated in MATLAB. The diffuse scattered field from compressed Polyethylene (PE) pellets containing steel spheres was measured in both transmission and reflection using a THz time domain spectroscopy (THz-TDS) system. Measurement results showed energy redistribution by granular media due to volume scattering as well as angle dependent spectral features due to Mie scattering. The RT model was validated by successfully reproducing qualitative features observed in experimental results. Diffuse intensity from granular media containing Teflon, lactose sugar, and C4 explosive was then calculated using the RT models. Simulation results showed the amplitude of diffuse intensity is affected by factors such as grain size, fractional volume of grains, thickness of scattering layer, and scattering angles. Spectral features were also observed in the diffuse intensity spectra from media containing grains with THz spectral signatures. The simulation results suggest the possibility of identifying materials from diffuse intensity spectra.

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Freeman, Will. "Terahertz quantum cascade structures using step wells and longitudinal optical-phonon scattering." Monterey, Calif. : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/dissert/2009/Jun/09Jun%5FFreeman%5FPhD.pdf.

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Dissertation (Ph.D. in Physics)--Naval Postgraduate School, June 2009.
Dissertation supervisor: Karunasiri, Gamani. "June 2009." Description based on title screen as viewed on July 14, 2009. Author(s) subject terms: Terahertz, THz, Quantum cascade structure, QC structure, Quantum cascade laser, QCL, Step well, Longitudinal optical-phonon, LO-phonon, Electron-phonon scattering, Electronelectron scattering, Impurity scattering, Interface roughness scattering, Optical transition, Electron transport, Monte Carlo method, Metal-metal waveguide, Surface plasmon waveguide Includes bibliographical references (p. 103-108). Also available in print.

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Prophete, Clotilde. "Etude de la propagation des ondes térahertz en milieu diffusant pour l'imagerie pour hélicoptères en condition de brownout." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLET040.

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Le brownout est un nuage de sable soulevé par le souffle du rotor de l'hélicoptère en milieu désertique. Ce nuage peut être épais de plusieurs dizaines de mètres et atténue, voire annule, la visibilité du pilote. Une solution est d'embarquer sur l'aéronef un système d'imagerie qui permettrait de visualiser la zone d'atterrissage à travers ce nuage de sable. Un tel système doit présenter des propriétés particulières. L'onde doit pouvoir pénétrer à travers le milieu diffusant et apporter une résolution suffisante pour détecter des obstacles. Le système doit aussi être compact et fonctionner en temps réel.La bande sub-terahertz semble la plus appropriée car elle répond a priori à tous ces critères. A notre connaissance, aucune étude théorique complète évalue les performances d'un imageur sub-térahertz en condition de brownout.De plus, certaines évaluations expérimentales réalisées jusqu'à aujourd'hui semblent incohérentes entre elles.Nous proposons donc un modèle complet, que nous avons confronté avec succès avec une simulation Monte Carlo, pour évaluer les performances d'un tel imageur. Dans un second temps, nous présentons une expérience originale de mesure d'atténuation simultanée dans le térahertz et le visible par une suspension de sable. L'efficacité d'extinction dans la bande THz peut directement être extraite de ces mesures simultanées. Nous pouvons aussi déduire la densité des particules en suspension ainsi que l'indice de réfraction des particules dans le THz
Brownouts are sand clouds stirred by the airflow of the helicopter rotor in arid areas. This cloud can be tens-of-meters thick and reduces or even cancels the pilot's visibility. A solution is to provide an imaging system embedded on the helicopter that would allow the pilot to visualize the landing area through the sand cloud. Such a system must meet specific criteria. The wave must be able to penetrate the scattering medium and give a sufficient resolution to detect obstacles. The system must also be compact and must work in real time.The sub-terahertz band seems to be the most adequate because it a priori complies with all the requirements. To our knowledge, the performance a sub-terahertz imaging system in brownout condition has never been completely evaluated yet. Besides, some of the existing experimental studies do not seem to be consistent between each other.Thus, we propose an accurate model, which was successfully compared to a Monte Carlo simulation, to evaluate the efficiency of such an imager. Second, we present an innovative experiment to measure simultaneously the attenuation by suspended sand in the terahertz and the visible bands. The extinction efficiency in the THz band can directly be known from these simultaneous measurements. The density of suspended particles and their refractive index in the THz band can also be deduced

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Dolguikh, Maxim. "MONTE CARLO SIMULATION OF HOLE TRANSPORT AND TERAHERTZ AMPLIFICATION IN MULTILAYER DELTA DOPED SEMICONDUCTOR STRUCTURES." Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3882.

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Monte Carlo method for the simulation of hole dynamics in degenerate valence subbands of cubic semiconductors is developed. All possible intra- and inter-subband scattering rates are theoretically calculated for Ge, Si, and GaAs. A far-infrared laser concept based on intersubband transitions of holes in p-type periodically delta-doped semiconductor films is studied using numerical Monte-Carlo simulation of hot hole dynamics. The considered device consists of monocrystalline pure Ge layers periodically interleaved with delta-doped layers and operates with vertical or in-plane hole transport in the presence of a perpendicular in-plane magnetic field. Inversion population on intersubband transitions arises due to light hole accumulation in E B fields, as in the bulk p-Ge laser. However, the considered structure achieves spatial separation of hole accumulation regions from the doped layers, which reduces ionized-impurity and carrier-carrier scattering for the majority of light holes. This allows remarkable increase of the gain in comparison with bulk p-Ge lasers. Population inversion and gain sufficient for laser operation are expected up to 77 K. Test structures grown by chemical vapor deposition demonstrate feasibility of producing the device with sufficient active thickness to allow quasioptical electrodynamic cavity solutions. The same device structure is considered in GaAs. The case of Si is much more complicated due to strong anisotropy of the valence band. The primary new result for Si is the first consideration of the anisotropy of optical phonon scattering for hot holes.
Ph.D.
Department of Physics
Arts and Sciences
Physics

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Gallat, Francois-Xavier. "Dynamique des protéines et de la couche d'hydratation étudiée par diffusion de neutrons et méthodes biophysiques complémentaires." Thesis, Grenoble, 2011. http://www.theses.fr/2011GRENY061/document.

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Ce travail de cette thèse porte sur la dynamique des protéines, accompagnées de leur eau d'hydratation, une couche de solvant autour des protéines vitale pour leur fonction biologique. Chacune de ces deux composantes s'accompagne d'une dynamique qui lui est propre et dont la réunion reforme le paysage énergétique du système biologiquement actif. La mise en application conjointe de la deutération sélective, de la diffusion incohérente de neutrons ainsi que la spectroscopie terahertz a permis d'explorer de manière indépendante la dynamique des protéines et de celles des couches d'hydratation. L'influence de l'état de repliement de la protéine sur sa dynamique a été étudié par diffusion élastique de neutrons. Les protéines globulaires se sont montrées moins dynamiques que ses analogues intrinsèquement désordonnées. Eux même semblent être plus rigides que les protéines dépliées non physiologiques. L'état d'oligomérisation et les conséquences sur la dynamique de ces protéines ont été développés. Les agrégats d'une protéine globulaire se sont avérés être plus flexibles que la forme soluble. A l'inverse, les agrégats d'une protéine désordonnée voient leur dynamique moyenne baisser par rapport à la forme soluble. Ces observations témoignent de la grande diversité de dynamiques à travers le protéome. Les expériences de diffusion incohérente de neutrons sur les couches d'hydratation des protéines globulaires et désordonnées ont permis d'obtenir des informations sur la nature des mouvements de l'eau autour des protéines. Les mesures ont mis en évidence la présence de mouvements translationnels concomitants à l'apparition de la transition dynamique dans les couches d'hydratations, vers 220 K. Les mesures ont de même montré un couplage plus fort entre une protéine désordonnée et son eau d'hydratation que celui entre une protéine globulaire et son eau d'hydratation. La nature de la couche d'hydratation et son influence sur sa dynamique ont été explorés, avec l'utilisation de polymères qui miment le comportement de l'eau et agissent comme source de flexibilité pour la protéine. Pour terminer, la dynamique des groupements méthyles, impliqués dans les modifications dynamiques observées à 150 et 220 K, a été étudiée
This thesis work focused on the dynamics of proteins, surrounded by their hydration layer, a water shell around the protein vital for its biological function. Each of these components is accompanied by a specific dynamics which union reforms the complex energy landscape of the system. The joint implementation of selective deuteration, incoherent neutron scattering and terahertz spectroscopy allowed to explore the dynamics of proteins and that of the hydration shell. The influence of the folding state of protein on its dynamics has been studied by elastic neutron scattering. Globular proteins were less dynamic than its intrinsically disordered analogues. Themselves appear to be stiffer than non physiological unfolded proteins. The oligomerization state and the consequences on the dynamics were investigated. Aggregates of a globular protein proved to be more flexible than the soluble form. In contrast, aggregates of a disordered protein showed lower average dynamics compared to the soluble form. These observations demonstrate the wide range of dynamics among the proteome. Incoherent neutron scattering experiences on the hydration layer of globular and disordered proteins have yielded information on the nature of water motion around these proteins. The measurements revealed the presence of translational motions concomitant with the onset of the transition dynamics of hydration layers, at 220 K. Measurements have also shown a stronger coupling between a disordered protein and its hydration water, compared to a globular protein and its hydration shell. The nature of the hydration layer and its influence on its dynamics has been explored with the use of polymers that mimic the water behavior and that act as a source of flexibility for the protein. Eventually, the dynamics of methyl groups involved in the dynamical changes observed at 150 and 220 K, was investigated

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Maëro, Simon. "Étude sous champ magnétique de nouvelles structures quantiques pour la photonique infrarouge et térahertz." Thesis, Paris, Ecole normale supérieure, 2014. http://www.theses.fr/2014ENSU0022/document.

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Ce travail de thèse est constitué de l’étude sous champ magnétique de trois systèmes quantiquesd’un grand intérêt pour leurs propriétés électroniques et leurs applications potentielles àla photonique infrarouge et terahertz : deux structures à cascade quantique, l’une détectrice etl’autre émettrice, et le graphène épitaxié sur SiC face carbone. Le détecteur à cascade quantique enGaAs/AlGaAs, fonctionnant vers 15m, a été étudié dans l’obscurité et sous illumination, pour identifierles chemins électroniques intervenant dans le courant noir et en fonctionnement. Le développementd’un modèle de photocourant a permis d’identifier les paramètres-clé régissant le fonctionnementdu détecteur. L’étude, en fonction de la polarisation et de la température, d’un laser à cascadequantique térahertz en InGaAs/GaAsSb doté d’une structure nominalement symétrique montrel’impact de la rugosité d’interface sur les performances du laser. Nous montrons que le système d’hétérostructurede type II InGaAs/GaAsSb est prometteur pour le développement de lasers à cascadequantique térahertz fonctionnant à haute température. Enfin, l’étude magnéto-spectroscopique dugraphène épitaxié a montré, outre les transitions entre niveaux de Landau du graphène monocoucheidéal, une signature supplémentaire que nous avons attribuée au désordre, et plus particulièrementà l’existence de lacunes de carbone. Une modélisation des défauts sous la forme d’un potentiel deltareproduit remarquablement nos résultats expérimentaux, ce qui constitue la première mise en évidenceexpérimentale des effets des défauts localisés sur les propriétés électroniques du graphène.La structure des niveaux de Landau perturbée par le désordre est clairement établie
This work reports on the study under magnetic field of three interesting quantumsystems, which present remarkable electronic properties and potential applications for infrared andterahertz photonics : two quantum cascade structures, one detector and one emitter, as well asepitaxial graphene layers grown on the carbon face of SiC. The GaAs/AlGaAs quantum cascade detector,designed to work around 15m, was studied both with and without illumination in order toidentify the electronic paths responsible for the dark current and the photocurrent. The developmentof a photocurrent model allowed us to identify the key points controlling the electronic transport.The investigation, as a function of the temperature and bias voltage, of a InGaAs/GaAsSb quantumcascade laser with a nominally symmetric structure shows the influence of interface roughness onthe laser performances. We demonstrate that the InGaAs/GaAsSb type II heterostructure system ispromising for developing terahertz quantum cascade lasers working at high temperature. Finally,magneto-spectroscopy experiments performed on epitaxial graphene display, besides the transitionsbetween Landau levels of monolayer graphene, additional signatures that we attribute to disorder,more specifically to carbon vacancies. Calculations using a delta-like potential for modeling thedefects are in good agreement with the experimental results. This study is the first experimental demonstrationof the influence of localized defects on the graphene electronic properties. The disorderperturbed Landau level structure is clearly established

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Chaix, Laura. "Couplage magnéto-électrique dynamique dans les composés multiferroïques : langasites de fer et manganites hexagonaux." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENY031/document.

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Cette thèse expérimentale a pour motivation l'étude des propriétés dynamiques des composés multiferroïques : les langasites de fer Ba3NbFe3Si2O14 et Ba3TaFe3Si2O14 et le manganite hexagonal ErMnO3. Ces investigations ont été réalisées grâce à l'utilisation de deux techniques expérimentales complémentaires : les spectroscopies FIR et THz et la diffusion de neutrons (polarisés et non polarisés). Dans les langasites de fer, des excitations magnéto-électriques ont été observées. Celles-ci ont été interprétées comme des modes de rotation atomique excités par la composante magnétique de l'onde électromagnétique. D'autre part, des modulations fines de la structure magnétique ont également été mises en évidence dans le composé Ba3NbFe3Si2O14 par l'observation de faits expérimentaux incompatibles avec la structure magnétique publiée avant cette étude. Il s'agissait de satellites magnétiques interdits et d'ordre supérieurs ainsi qu'une extinction dans les ondes de spin. La structure magnétique déduite de cette étude correspond à une modulation en accordéon des hélices de spin et à une perte structurale de l'axe de rotation d'ordre 3. Ces modulations sont compatibles avec les excitations magnéto-électriques et la multiferroïcité récemment mise en évidence dans ce composé. En parallèle, les propriétés magnéto-électriques dynamiques du manganite hexagonal ErMnO3 ont été étudiées. Un électromagnon a été observé correspondant à un magnon du Mn excité par la composante électrique de l'onde électromagnétique. Par comparaison avec le composé YMnO3, cet électromagnon a été interprété comme résultant d'une hybridation entre une excitation de champ cristallin de l'Er active électriquement et un magnon standard du Mn
This experimental thesis is motivated by the study of the dynamical properties of multiferroic compounds : the iron langasites Ba3NbFe3Si2O14 and Ba3TaFe3Si2O14 and the hexagonal manganite ErMnO3. These investigations were performed using two complementary experimental techniques : FIR and THz spectroscopy and neutron scattering (with polarized and unpolarized neutrons). In the iron langasites, magnetoelectric excitations were observed. These excitations have been interpreted as atomic rotation modes excited by the magnetic component of the electromagnetic wave. On the other hand, weak modulations of the magnetic structure were also evidence in the Ba3NbFe3Si2O14 compound by observing experimental evidence inconsistent with the published magnetic structure. These evidence were forbidden and higher order magnetic satellites as well as an extinction in the spin-waves spectrum. The magnetic order deduced from this study presents a bunched modulation of the helix and the structural loss of the 3-fold axis. These modulations are compatible with the magnetoelectric excitations and the multiferroicity recently evidenced in this compound. In parallel, the magnetoelectric dynamical properties of the hexagonal manganite ErMnO3 have been investigated. An electromagnon has been observed corresponding to a Mn magnon excited by the electric component of the electromagnetic wave. From comparison with the YMnO3 compound, this electromagnon was interpreted as a hybrid mode between an electricallyactive Er crystal field excitation and a Mn magnon

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Ryder, Matthew. "Physical phenomena in metal-organic frameworks : mechanical, vibrational, and dielectric response." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:c7a51278-19d7-45ae-825a-bac8040775a7.

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This thesis entails the utilisation of ab initio density functional theory (DFT) in conjunction with neutron and synchrotron spectroscopy to study the mechanical, vibrational, and dielectric response of metal-organic framework (MOF) materials at the molecular level. MOFs are crystalline materials with nanoscale porosity, which have garnered immense scientific and technological interest for a wide variety of innovative engineering applications. One part of the thesis involves using low-frequency lattice vibrations to characterise the various physical motions that are possible for framework materials. These collective modes detected at terahertz (THz) frequencies have been used to reveal a broad range of exciting possibilities. New evidence has been established to demonstrate that THz modes are intrinsically linked to anomalous elasticity underpinning gate-opening and pore-breathing mechanisms, and to shear-induced phase transitions and the onset of structural instability. The phenomenon of molecular rotor mechanisms and trampoline-like motions are also observed, along with the first experimental confirmation of coordinated shear dynamics. Additionally, a new method to characterise the effects of temperature, and hence thermally-induced structural amorphisation is reported. Finally, for the first time, the frequency-dependent (dynamic) dielectric response of MOF materials, across the extended infrared (IR) spectral region was reported. The results were obtained from experimental synchrotron radiation IR reflectivity and DFT to reveal the low-к dielectric response of MOFs and established structure-property trends that highlight them as promising systems for microelectronic device applications.

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Pearce, Jeremiah Glen. "Multiple scattering of broadband terahertz pulses." Thesis, 2005. http://hdl.handle.net/1911/18797.

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Propagation of single-cycle terahertz (THz) pulses through a random medium leads to dramatic amplitude and phase variations of the electric field because of multiple scattering. We present the first set of experiments that investigate the propagation of THz pulses through scattering media. The scattering of short pulses is a relevant subject to many communities in science and engineering, because the properties of multiply scattered or diffuse waves provide insights into the characteristics of the random medium. For example, the depolarization of diffuse waves has been used to form images of objects embedded in inhomogeneous media. Most of the previous scattering experiments have used narrowband optical radiation where measurements are limited to time averaged intensities or autocorrelation quantities, which contain no phase information of the pulses. In the experiments presented here, a terahertz time-domain spectrometer (THz-TDS) is used. A THz-TDS propagates single-cycle sub-picosecond pulses with bandwidths of over 1 THz into free space. The THz-TDS is a unique tool to study such phenomena, because it provides access to both the intensity and phase of those pulses through direct measurement of the temporal electric field. Because of the broad bandwidth and linear phase of the pulses, it is possible to simultaneously study Rayleigh scattering and the short wavelength limit in a single measurement. We study the diffusion of broadband single-cycle THz pulses by propagating the pulses through a highly scattering medium. Using the THz-TDS, time-domain measurements provide information on the statistics of both the amplitude and phase of the diffusive waves. We develop a theoretical description, suitable for broadband radiation, which accurately describes the experimental results. We measure the time evolution of the degree of polarization, and directly correlate it with the single-scattering regime in the time domain. Measurements of the evolution of the temporal phase of the radiation demonstrate that the average spectral content depends on the state of polarization. In the case of broadband radiation, this effect distinguishes photons that have been scattered only a few times from those that are propagating diffusively.

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Kaushik, Mayank. "Characterizing and mitigating scattering effects in terahertz time domain spectroscopy measurements." Thesis, 2013. http://hdl.handle.net/2440/83605.

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Terahertz research has came a long way since its inception in the mid 1980s when the first pulsed THz emission was reported using electro-optic sampling. With rapid advent in THz generation and detection techniques, research in terahertz time-domain spectroscopy (THz-TDS) has progressed to such a great extent that terahertz is finding potential use in real world applications such as biomedical sensing, security screening and defence related applications. While many researchers and commercial organizations have successfully demonstrated efficacy of terahertz, various challenges still exist before THz technology transitions from the realm of research into everyday life. This thesis focuses on the topical area of characterization and mitigation of scattering in terahertz time-domain spectroscopy measurements. Motivated by the lack of theoretical models and signal processing techniques, this thesis, presents several pieces of novel work that include theoretical models, numerical methods, signal processing techniques and experimental procedures to estimate and mitigate the scattering contribution in THz-TDS measurements of dielectric materials. The thesis is divided in to three main sections: Section I describes the various theoretical models developed for estimating and approximating the scattering cross-section, when an electromagnetic wave interacts with a random medium with characteristic particle dimensions comparable to the wavelength of the incident radiation. The section is divided in two main sub-sections, (i) scattering through a sparse distribution of particles, and (ii) scattering from dense media. Section II presents several signal processing based approaches for estimating and mitigating scattering effects in THz-TDS measurements for samples that exhibit sharp and sparse absorption features, without requiring a priori information such as its granularity, refractive index, and density. Section III discusses some common experimental techniques such as milling the material of interest into fine powder and time domain averaging spatially disjoint or multiple sample measurements, in order to reduce the presence of scattering features and effects in the THz-TDSmeasurements. Recognizing the invasive access and/or specializedmeasurement apparatus requirement for these techniques, we present our preliminary investigation in analysing multiple Fresnel echoes for estimating and mitigating scattering contribution in THz-TDS measurements. In addition to this, the thesis offers an introductory background to THz-TDS, in areas of hardware, applications, signal processing, and terahertz interaction with matter.
Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2013

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Частини книг з теми "Terahertz; scattering"

Zurk, L. M., and S. Schecklman. "Terahertz Scattering." In Terahertz Spectroscopy and Imaging, 95–116. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-29564-5_5.

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Schwartz, H., K. F. Renk, A. Berke, A. P. Mayer, and R. K. Wehner. "Terahertz-Phonons in Diamond." In Phonon Scattering in Condensed Matter V, 362–64. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-82912-3_103.

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Yu, Yang, Jin Li, and Rui Min. "A Scattering Model Based on GTD in Terahertz Band." In The Proceedings of the Second International Conference on Communications, Signal Processing, and Systems, 879–86. Cham: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-00536-2_101.

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Xu, Zhengwu, Yuanjie Wu, Jin Li, and Yiming Pi. "GTD-Based Model of Terahertz Radar Scattering Center Distance Estimation Method." In Lecture Notes in Electrical Engineering, 477–83. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-5803-6_48.

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Cheville, R. Alan, Matthew T. Reiten, Roger McGowan, and Daniel R. Grischkowsky. "Applications of Optically Generated Terahertz Pulses to Time Domain Ranging and Scattering." In Springer Series in Optical Sciences, 237–93. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-540-45601-8_6.

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Dolganova, Irina N., Stanislav O. Yurchenko, Valeriy E. Karasik, and Vladimir P. Budak. "Peculiarity of Terahertz Waves Scattering." In Selected Topics in Electronics and Systems, 61–66. WORLD SCIENTIFIC, 2015. http://dx.doi.org/10.1142/9789814725200_0004.

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M. Wiecha, Matthias, Amin Soltani, and Hartmut G. Roskos. "Terahertz Nano-Imaging with s-SNOM." In Terahertz Technology [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.99102.

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Spectroscopy and imaging with terahertz radiation propagating in free space suffer from the poor spatial resolution which is a consequence of the comparatively large wavelength of the radiation (300 μm at 1 THz in vacuum) in combination with the Abbe diffraction limit of focusing. A way to overcome this limitation is the application of near-field techniques. In this chapter, we focus on one of them, scattering-type Scanning Near-field Optical Microscopy (s-SNOM) which − due to its versatility − has come to prominence in recent years. This technique enables a spatial resolution on the sub-100-nm length scale independent of the wavelength. We provide an overview of the state-of-the-art of this imaging and spectroscopy modality, and describe a few selected application examples in more detail.

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Cunsolo, Alessandro. "Using X-ray as a Probe of the Terahertz Dynamics of Disordered Systems – Complementarity with Inelastic Neutron Scattering and Future Perspectivess." In Neutron Scattering. InTech, 2016. http://dx.doi.org/10.5772/62844.

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Svintsov, D., V. Ryzhii, A. Satou, T. Otsuji, and V. Vyurkov. "Carrier-Carrier Scattering and Negative Dynamic Conductivity in Pumped Graphene *." In Graphene-Based Terahertz Electronics and Plasmonics, 407–28. Jenny Stanford Publishing, 2020. http://dx.doi.org/10.1201/9780429328398-26.

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"Research on Terahertz Scattering Characteristics of the Precession Cone." In Current Trends in Computer Science and Mechanical Automation Vol.1, 620–29. De Gruyter Open Poland, 2017. http://dx.doi.org/10.1515/9783110584974-064.

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Тези доповідей конференцій з теми "Terahertz; scattering"

Zurk, L. M., B. Orlowski, G. Sundberg, D. P. Winebrenner, E. I. Thorsos, and A. Chen. "Electromagnetic scattering calculations for terahertz sensing." In Integrated Optoelectronic Devices 2007, edited by Kurt J. Linden and Laurence P. Sadwick. SPIE, 2007. http://dx.doi.org/10.1117/12.698720.

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Zurk, L. M., G. Sundberg, S. Schecklman, Z. Zhou, A. Chen, and E. I. Thorsos. "Scattering effects in terahertz reflection spectroscopy." In SPIE Defense and Security Symposium, edited by James O. Jensen, Hong-Liang Cui, Dwight L. Woolard, and R. Jennifer Hwu. SPIE, 2008. http://dx.doi.org/10.1117/12.784222.

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Nosich, Alexander I., and Mikhail V. Balaban. "Terahertz wave scattering by a graphene disk." In 2013 21st International Conference on Applied Electromagnetics and Communications (ICECom). IEEE, 2013. http://dx.doi.org/10.1109/icecom.2013.6684748.

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Huang, S. X., X. Y. Guo, and M. Y. Xia. "Terahertz Wave Scattering by Skin Cancer Tissues." In 2018 IEEE International Conference on Computational Electromagnetics (ICCEM). IEEE, 2018. http://dx.doi.org/10.1109/compem.2018.8496625.

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Grossman, Erich N., Nina Popovic, Richard Chamberlin, Joshua Gordon, and David Novotny. "Bistatic terahertz scattering from random rough surfaces." In Passive and Active Millimeter-Wave Imaging XXII, edited by Duncan A. Robertson and David A. Wikner. SPIE, 2019. http://dx.doi.org/10.1117/12.2518754.

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Garg, Diksha, Aparajita Bandyopadhyay, and Amartya Sengupta. "Scattering: Challenge of Terahertz Time Domain Spectroscopy." In Frontiers in Optics. Washington, D.C.: OSA, 2019. http://dx.doi.org/10.1364/fio.2019.jtu4a.24.

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Swift, G. P., J. R. Fletcher, A. J. Gallant, De Chang Dai, J. A. Levitt, and J. M. Chamberlain. "Scattering of Terahertz Radiation from Random Structures." In >2006 Joint 31st International Conference on Infrared Millimeter Waves and 14th International Conference on Teraherz Electronics. IEEE, 2006. http://dx.doi.org/10.1109/icimw.2006.368361.

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Siday, Tom, Lucy L. Hale, Rodolfo I. Hermans, and Oleg Mitrofanov. "Terahertz nano-spectroscopy with resonant scattering probes." In 2020 45th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz). IEEE, 2020. http://dx.doi.org/10.1109/irmmw-thz46771.2020.9370491.

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Zurk, Lisa M., Brian Orlowski, Garth Sundberg, Zhen Zhou, and Antao Chen. "Terahertz scattering from a rough granular surface." In 2007 IEEE Antennas and Propagation Society International Symposium. IEEE, 2007. http://dx.doi.org/10.1109/aps.2007.4396650.

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Siday, Thomas, Michele Natrella, Jiang Wu, Huiyun Liu, and Oleg Mitrofanov. "Resonant scattering probes in the terahertz range." In 2017 42nd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz). IEEE, 2017. http://dx.doi.org/10.1109/irmmw-thz.2017.8067247.

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Звіти організацій з теми "Terahertz; scattering"

Nam, Kyung. Modeling Terahertz Diffuse Scattering from Granular Media Using Radiative Transfer Theory. Portland State University Library, January 2000. http://dx.doi.org/10.15760/etd.380.

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