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Auswahl der wissenschaftlichen Literatur zum Thema „TERAHERTZ (THZ) RADIATION“

Autor: Grafiati

Veröffentlicht am 11. September 2023

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Zeitschriftenartikel zum Thema "TERAHERTZ (THZ) RADIATION"

Zainullin, F. A., D. I. Khusyainov, M. V. Kozintseva und A. M. Buryakov. „Polarization analysis of THz radiation using a wire grid polarizer and ZnTe crystal“. Russian Technological Journal 10, Nr. 3 (09.06.2022): 74–84. http://dx.doi.org/10.32362/2500-316x-2022-10-3-74-84.

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Objectives. Terahertz time domain spectroscopy (THz-TDS) is currently a promising research method in pharmacology and medicine due to the high sensitivity of terahertz radiation to the chemical composition and molecular structure of organic compounds. However, due to the chirality of many biomolecules, their analysis is performed by THz irradiation with circular dichroism. In particular, circular dichroism of THz radiation allows the study of “soft” vibrational movements of biomolecules with different chiralities. Therefore, when studying such biological materials, accurate control of THz radiation parameters is essential. The paper describes a method for characterizing THz radiation polarization on the example of a black phosphorus source material.Methods. The analysis of polarization parameters of THz radiation experimentally obtained by THz-TDS and using terahertz polarizers was performed by mathematical modeling of the interaction between THz radiation and a ZnTe crystal as a detector.Results. Two schemes of terahertz spectroscopy with the ZnTe crystal as the detector were discussed in detail. The polarization parameters were determined using one or two wire-grid THz polarizers. An expression for approximating the dependences of the peak-to-peak amplitude of THz radiation on the rotation angle of the wire-grid THz polarizer for these cases was derived. The impact of the terahertz electric field intensity value on the shape of polarization dependences was considered. The rotation angle of the polarization ellipse of THz radiation emitted by the surface of a bulk-layered black phosphorus crystal illuminated by femtosecond laser pulses was determined.Conclusions. The amplitude of the THz radiation electric field intensity begins to impact the shape of polarization dependences when its value becomes comparable to or exceeds 40 kV/cm.

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Zabolotniy, A. G., I. A. Geiko und L. M. Balagov. „Terahertz radiation in ophthalmology (review)“. Acta Biomedica Scientifica 6, Nr. 6-1 (28.12.2021): 168–80. http://dx.doi.org/10.29413/abs.2021-6.6-1.20.

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Terahertz (THz) radiation is one of the new, intensively studied interdisciplinary fi elds of scientifi c knowledge, including medicine, in the fi rst decades of the 21st century. At the beginning of this article (review), in a brief form, the basic statements on THz radiation, the main parameters and properties are presented; the modern THz biophtonics technologies used in biology and medicine are considered – THz refl ectometry, THz spectroscopy methods. Then a number of directions and examples of possible use of THz technologies in biology and medicine, including pharmaceuticals, are given. The main part of the review presents the progress of experimental research and the prospects for the clinical application of medical technologies of THz spectroscopy, THz imaging, in ophthalmology in the study of the morphological and functional state of the ocular surface structures, diagnosis, medical testing, and treatment of ophthalmopathology of the ocular surface. The article concludes with a review of experimental studies on the safety of using THz waves for medical diagnostics and treatment of ophthalmopathology. In the fi nal part, the main problems and prospects of introducing medical THz technologies into the clinical practice of an ophthalmologist are considered.

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Khodzitsky, Mikhail K., Petr S. Demchenko, Dmitry V. Zykov, Anton D. Zaitsev, Elena S. Makarova, Anastasiia S. Tukmakova, Ivan L. Tkhorzhevskiy, Aleksei V. Asach, Anna V. Novotelnova und Natallya S. Kablukova. „Photothermal, Photoelectric, and Photothermoelectric Effects in Bi-Sb Thin Films in the Terahertz Frequency Range at Room Temperature“. Photonics 8, Nr. 3 (12.03.2021): 76. http://dx.doi.org/10.3390/photonics8030076.

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The terahertz frequency range is promising for solving various practically important problems. However, for the terahertz technology development, there is still a problem with the lack of affordable and effective terahertz devices. One of the main tasks is to search for new materials with high sensitivity to terahertz radiation at room temperature. Bi1−xSbx thin films with various Sb concentrations seem to be suitable for such conditions. In this paper, the terahertz radiation influence onto the properties of thermoelectric Bi1−xSbx 200 nm films was investigated for the first time. The films were obtained by means of thermal evaporation in vacuum. They were affected by terahertz radiation at the frequency of 0.14 terahertz (THz) in the presence of thermal gradient, electric field or without these influences. The temporal dependencies of photoconductivity, temperature difference and voltage drop were measured. The obtained data demonstrate the possibility for practical use of Bi1−xSbx thin films for THz radiation detection. The results of our work promote the usage of these thermoelectric materials, as well as THz radiation detectors based on them, in various areas of modern THz photonics.

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Khusyainov, D. I., A. V. Gorbatova und A. M. Buryakov. „Terahertz generation from surface of the bulk and monolayer tungsten diselenide“. Russian Technological Journal 8, Nr. 6 (18.12.2020): 121–29. http://dx.doi.org/10.32362/2500-316x-2020-8-6-121-129.

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The study of ultrafast laser interaction with graphene-like materials based on transition metal dichalcogenides attracts most scientific groups. It is connected with potential use of these materials in flexible optoelectronic devices of visible and THz range. In this paper the parameters of generation of terahertz field from the surface of bulk layered crystal and monolayer film of tungsten diselenide are analyzed. Generation of terahertz radiation from the surface of experimental samples was studied by the terahertz time-domain spectroscopy in reflection geometry. Bulk layered crystals of tungsten diselenide were grown by gas transport reactions. Monolayers of tungsten diselenide crystals were grown by chemical vapor deposition on a silicon substrate. The bandwidth of the generated terahertz radiation from the surface of the bulk layered tungsten diselenide crystal was ~ 3.5 THz. For tungsten diselenide monolayer the spectrum bandwidth of the generated THz radiation was ~ 2.5 THz. The peak amplitude of the generated terahertz field for both samples was at a frequency of ~ 1 THz. Research of the influence of the angle of rotation of a polarization plane of optical femtosecond pump on peak-to-peak amplitude of the generated terahertz field from the surface of investigated samples was carried out. Symmetry analysis of the azimuthal dependence of THz radiation made it possible to separate the mechanisms of THz radiation and evaluate their contribution. The analysis results confirm that the only possible contribution to the generation of terahertz radiation in a tungsten diselenide monolayer crystal is the second order nonlinear optical effect – optical rectification. One of the contributions to the generation of tungsten diselenide is a nonlinear-optical effect of the third order – surface optical rectification.

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Pfeifer, Tilo, und Stephan Bichmann. „THz-Imaging on its Way to Industrial Application“. Key Engineering Materials 437 (Mai 2010): 271–75. http://dx.doi.org/10.4028/www.scientific.net/kem.437.271.

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Terahertz radiation, which fills the gap between 100 GHz and 10 THz ( = 30 µm – 3 mm) in the electro-magnetic spectrum, has seldom been used outside of astronomy and other scientific research. However, in recent years there has been a significant interest in investigating THz radiation for different new applications. Especially the ability of terahertz radiation to penetrate deep into many organic materials without the damage associated with ionizing radiation such as X-rays lead to recent interests chiefly in the fields of security technology and biomedical imaging. The attribute of many different materials to be transparent for terahertz radiation, was also the reason for many difficulties in practical applications outside of research. Using radiation that can pass through so many materials so well makes detection difficult. In addition, sources to generate light at terahertz frequencies have suffered from low output intensity and other problems. Since the 1990s, technical breakthroughs in sources and detectors have brought terahertz technology within striking distance of significant commercial markets [1]. The pressure to develop new terahertz sources arose from two dramatically different groups - ultrafast timedomain spectroscopists who wanted to work with longer wavelengths, and long wavelength radio astronomers who wanted to work with shorter wavelengths. Today there are continuous-wave (CW) sources available as well as pulsed sources [2]. The aim of this paper is to provide an overview of key scientific developments which currently represent the basics of the mentioned THz technology. Beginning with the working principle of opto-electronic THz sources and detectors, the paper explains different setups for transmitting and using THz radiation. Furthermore it shows different applications of different business branches and gives an outlook for industrial application in the fields of metrology and quality control.

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Sabluk, A. V., und A. A. Basharin. „Terahertz radiation converter based on metamaterial“. Izvestiya Vysshikh Uchebnykh Zavedenii. Materialy Elektronnoi Tekhniki = Materials of Electronics Engineering 26, Nr. 1 (14.04.2023): 56–65. http://dx.doi.org/10.17073/1609-3577-2023-1-56-65.

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Since the early 1980s, the terahertz range (from 0.1 to 10 THz) attracts constant attention of both fundamental and applied physics. Due to its unique properties, terahertz radiation finds it’s applications in spectroscopy, defectoscopy, and security systems. The construction of efficient absorbers and converters in terahertz range is crucial for further development of terahertz technologies. In this work, we use a frequency-selective high-Q metamaterial to construct a converter of terahertz radiation into the infrared radiation. The converter consists of a metamaterial absorber of terahertz radiation covered with a micrometer thick layer of graphite, which emits in the infrared range the energy absorbed by the metamaterial. We have made a numerical electrodynamic and associated thermal simulation of the radiation converter. The metamaterial simulation at 96 GHz (low opacity window of the atmosphere) shows the electromagnetic radiation absorption coefficient of 99.998%, and the analytically calculated converter efficiency of 93.8%. Concluding the above our terahertz radiation converter may contribute to security systems and defectoscopy setups.

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Zhao, Li, Ruhan Yi, Sun Liu, Yunliang Chi, Shengzhi Tan, Ji Dong, Hui Wang et al. „Biological responses to terahertz radiation with different power density in primary hippocampal neurons“. PLOS ONE 18, Nr. 1 (20.01.2023): e0267064. http://dx.doi.org/10.1371/journal.pone.0267064.

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Terahertz (THz) radiation is a valuable imaging and sensing tool which is widely used in industry and medicine. However, it biological effects including genotoxicity and cytotoxicity are lacking of research, particularly on the nervous system. In this study, we investigated how terahertz radiation with 10mW (0.12 THz) and 50 mW (0.157 THz) would affect the morphology, cell growth and function of rat hippocampal neurons in vitro.

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Zhang, Xingyun, Fangyuan Zhan, Xianlong Wei, Wenlong He und Cunjun Ruan. „Performance Enhancement of Photoconductive Antenna Using Saw-Toothed Plasmonic Contact Electrodes“. Electronics 10, Nr. 21 (04.11.2021): 2693. http://dx.doi.org/10.3390/electronics10212693.

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A photoconductive logarithmic spiral antenna with saw-toothed plasmonic contact electrodes is proposed to provide a higher terahertz radiation compared with the conventional photoconductive antenna (PCA). The use of saw-toothed plasmonic contact electrodes creates a strong electric field between the anode and cathode, which generates a larger photocurrent and thereby effectively increases the terahertz radiation. The proposed PCA was fabricated and measured in response to an 80 fs optical pump from a fiber-based femtosecond laser with a wavelength of 780 nm. When the proposed antenna is loaded with an optical pump power of 20 mW and a bias voltage of 40 V, a broadband pulsed terahertz radiation in the frequency range of 0.1–2 THz was observed. Compared to the conventional PCA, the THz power measured by terahertz time domain spectroscopy (THz-TDS) increased by an average of 10.45 times.

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Fu, Xiao Jian, und Ji Zhou. „The Applications of Terahertz Spectroscopy in Functional Optical Materials Researches“. Applied Mechanics and Materials 320 (Mai 2013): 133–37. http://dx.doi.org/10.4028/www.scientific.net/amm.320.133.

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Terahertz radiation refers to the electromagnetic wave whose frequency is usually defined between 0.1 and 10 THz (1 THz=1012 Hz). With the development of the emission and detection technologies of THz radiation, terahertz time-domain spectroscopy (THz-TDS) has been widely used in medical diagnosis, security inspection and materials characterization. In this paper, we introduced briefly the progress of terahertz measurement technologies, and then reviewed the applications of THz spectra in functional materials researches. As two important functional optical materials, TiO2 nanoparticles and yttrium aluminum garnet (YAG) crystal have been investigated with THz-TDS. We introduced the electron injection process in TiO2 studied by time resolved THz spectroscopy which is reported in the literature, and then presented our own work, the THz optical constants of undoped and Tm3+ doped YAG crystals.

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Sidorov A. V., Veselov A. P., Vodopyanov A. V., Kubarev V. V., Gorbachev Ya. I. und Shevchenko O. A. „Features of the breakdown in heavy noble gases under the action of Novosibirsk free electron laser radiation“. Technical Physics Letters 49, Nr. 2 (2023): 14. http://dx.doi.org/10.21883/tpl.2023.02.55362.19424.

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The results of experimental studies on the breakdown of noble gases (argon and krypton) by terahertz radiation from the Novosibirsk free electron laser (NovoFEL) are presented. For the first time, the breakdown thresholds of noble gases by terahertz radiation were measured in a wide pressure range (0.2-1.5 bar). Previous experiments to measure breakdown thresholds in the THz range in various gases were carried out for hundreds of GHz or at atmospheric pressure. Experimental breakdown thresholds are compared with calculated data using various simplified models. Keywords: THz radiation, gas breakdown, THz laser discharge.

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Dissertationen zum Thema "TERAHERTZ (THZ) RADIATION"

Numan, Nagla Numan Ali. „Terahertz (THz) spectroscopy“. Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71690.

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Thesis (MSc)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Terahertz radiation is currently used in security, information and communication technology (ICT), and biomedical sciences among others. The usability of terahertz (THz) radiation, in many of its applications depends on characteristics of the materials being investigated in the THz range. At the heart of THz usage is a THz spectroscopy system necessary for the generation and detection of the THz radiation. In this thesis, we characterise such a THz spectroscopy system. In our typical THz spectrometric system, we make use of femtosecond (fs) laser technology and pump-probe principles for emission and detection of THz radiation. Background about the principles of generation THz radiation using fs triggered antennas and the principles of the spectroscopy technique and appropriate literature references are presented. Using an assembled commercially available kit, we reproduce known spectra in order to confirm correct functionality (for calibration) of the assembled spectroscopy system and to gain experience in interpreting these spectra. By introducing a suitable x - y scanning device we construct a crude THz imaging device to illustrate the principle.
AFRIKAANSE OPSOMMING: Terahertsstraling word deesdae wyd in die sekuriteits, inligting-en-kommunikasie en biomediese sektore aangewend. Die gepastheid van terahertsstraling (THz) vir ’n spesifieke toepassings hang af van die eienskappe van die materiale wat ondersoek word. Vir die uitvoer van sulke eksperimente word ’n THz-spektroskopie sisteem benodig vir die opwekking en meting van THz-straling. In hierdie tesis word so ’n THz-spektroskopie sisteem beskou en gekarakteriseer. In die sisteem word van ’n femtosekondelaser (fs) gebruik gemaak in ’nn pomp-en-proef opstelling vir die uitstraling en meting van THz-straling. Die beginsels rakende die opwekking van THz-straling, deur gebruik te maak van ’n antenna wat deur ’n fs-laser geskakel word, asook die beginsels van die spektroskopiese tegniek, met toepaslike verwysings, word in die tesis aangebied. Deur gebruik te maak van’n kommersiële THz opstelling is bekende spektra gemeet om die korrekte funksionering (vir kalibrasie doeleindes) na te gaan en om ondervinding op te doen in die interpretasie van hierdie spektra. ’n X-Y-translasie toestel is tot die opstelling bygevoeg om THz-afbeelding moontlik te maak en sodoende hierdie beginsel te illustreer.

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Suzanovičienė, Rasa. „Investigation of carrier kinetics in semiconductors by terahertz radiation pulses“. Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20101116_163924-89818.

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Creation of ultrafast semiconductor components is inconceivable without understanding various processes of picoscond duration in semiconductors. These processes, as electron energy relaxation time or nonequiriblium carrier capture are very important for semiconductor photonics and terahertz range devices. Since now, the most popular tool of measuring ultrafast processes in semiconductors was picosecond or femtosecond laser pulses. In spite of excellent time resolution, optical pump – probe methods have a significant imperfection. Interpretation of the results can be very complicate. Also, the measured result can be affected by few variable parameters or interaction of various physical phenomenon. Therefore determinate results can be hardly related with electron time dependent characteristic. The aim of this dissertation was to measure electron energy relaxation times and electron life times by using terahertz pulses in narrow – gap semiconductors used for photoconductive terahertz emitters or detectors. In this dissertation, electron characteristic times witch describe various processes in semiconductor, were studied. These measurements were performed by optical pump – terahertz probe technique and time domain terahertz spectroscopy. The emission of terahertz pulses from the semiconductor surface, illuminated by femtosecond laser pulses, was investigated.
Ultrasparčių puslaidininkinių komponentų kūrimas reikalauja gilesnio supratimo apie tai, kaip puslaidininkiuose vyksta fizikiniai procesai, trunkantys kelias pikosekundes ar net mažiau nei vieną pikosekundę. Tokie reiškiniai, kaip elektronų impulso ir energijos relaksacija bei nepusiausvyrųjų krūvininkų pagavimas yra labai svarbūs puslaidininkinių fotonikos ir terahercinio diapazono prietaisų veikimui. Iki pastarojo meto pagrindinis ultrasparčiųjų procesų puslaidininkiuose tyrimo įrankis buvo optiniai metodai, kuriuose elektronų dinamikai stebėti buvo pasitelkiami pikosekundinių ar femtosekundinių lazerių impulsai. Nepaisant išskirtinai didelės šių metodų laikinės skyros, optinio kaupinimo-zondavimo matavimų rezultatus yra palyginti sudėtinga interpretuoti. Šie rezultatai dažniausiai yra įtakojami kelių sistemos parametrų kitimo ir įvairių fizikinių reiškinių tarpusavio sąveikos, todėl sunkiai susiejamas su kuria nors elektronų laikine charakteristika. Disertacijos darbo tikslas – naudojant terahercinės spinduliuotės impulsus išmatuoti elektronų impulso ir energijos relaksacijos trukmes keliuose siauratarpiuose puslaidininkiuose bei jų gyvavimo trukmes medžiagose, skirtose fotolaidžių terahercinės spinduliuotės emiterių ir detektorių gamybai. Šioje disertacijoje yra pateikiami įvairių charakteringų elektroninius procesus puslaidininkiuose apibūdinančių trukmių matavimų naudojant terahercinės spinduliuotės impulsus rezultatai. Tokie tyrimai atlikti ir optinio žadinimo –... [toliau žr. visą tekstą]

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But, Dmytro. „Détecteurs de radiation THz à base de silicium“. Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20170/document.

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Cette thèse est consacrée à l'étude des détecteurs de radiation THz basés sur des transistors à effet de champ qui ont été fabriqués en utilisant les technologies différentes. La photo-réponse de transistors à effet de champ a été étudiée dans une large gamme d'intensités de radiation: de 0,5 mW/cm2 à 500 kW/cm2, et pour des fréquences allant de 0,13 THz à 3,3 THz. Les détecteurs montrent la photo-réponse linéaire en fonction de l'intensité du rayonnement dans une large gamme d'intensités, jusqu'à plusieurs kW/cm2. Pour toutes les fréquences, nous avons observé que la région linéaire a été suivie par une partie non linéaire et ensuite par une saturation. Cet effet a conduit à un nouveau modèle de détecteurs FET à large bande qui est basé sur la connaissance phénoménologique de caractéristiques statiques de transistor. Le modèle prend en compte le comportement non linéaire du courant dans le canal dans toute une plage de fonctionnement du transistor, ce qui est particulièrement important à des intensités élevées de rayonnement THz. Les données expérimentales ont été interprétées avec succès dans le cadre du modèle développé
This thesis is devoted to study of terahertz detectors based on field-effect transistors fabricated using silicon technology and they comparison to InGaAs/InP ones. The main research effort was devoted to the problem of detectors linearity at high radiation intensities. The photoresponse of field effect transistors to terahertz radiation in a wide range of intensities: from 0.5 mW/cm2 up to 500 kW/cm2 and for frequencies from 0.13 THz to 3.3 THz was studied. This work shows that the photoresponse of all studied detectors increases linearly with increasing radiation intensity up to a few kW/cm2 range and is followed by the nonlinear and saturation parts for higher radiation intensities. This effect has led to the new model of broadband field-effect transistor detectors. The model is based on the phenomenological knowledge of the transistor static transfer characteristic and explains the photoresponse nonlinearity as related to non-linearity and saturation of the transistor channel current. The developed model explains consistently experimental data both in linear and nonlinear regions of terahertz detection

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Niklas, Andrew John. „Characterization of Structured Nanomaterials using Terahertz Frequency Radiation“. Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1347461386.

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Al-Ibadi, Amel. „Terahertz imaging and spectroscopy of biomedical tissues : application to breast cancer detection“. Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0059/document.

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Les travaux de cette thèse consistent à développer des outils de spectroscopie et d'imagerie térahertz pour des applications médicales. L'objectif est de déterminer le potentiel et l'efficacité de la spectroscopie térahertz et de l'imagerie dans la détection des régions cancéreuses et la distinction entre les tissus malades et sains pour le cancer du sein chez les femmes. La spectroscopie térahertz est une technique sans contact, non ionisante pour obtenir des résultats rapides, comparée à l'analyse clinique standard. Les études expérimentales sont divisées en deux sections principales :Section I :Cette partie se concentre sur la spectroscopie en utilisant un rayonnement THz. La maîtrise de cette technique permet de travailler en mode réflexion ou transmission avec des fréquences dans la bande passante térahertz. Plusieurs types de matériaux ont été utilisés comme fantômes pour la calibration de l'expérience : des solides (silice, téflon, saphir et verre), des liquides (méthanol, eau et alcool) et des tissus biologiques (cancer, fibres et gras), ainsi qu'un mélange (eau-méthanol). Les indices de réfraction, les coefficients d'absorption et les fonctions diélectriques complexes ont d'abord été mesurés et extraits puis fittés avec un modèle de Debye. Les tissus biologiques sont apparus hétérogènes en épaisseur et avec des surfaces qui peuvent être irrégulières, ce qui rend difficile l'extraction d'informations précises, en raison d’artefacts induits. Les signaux ont été traités en suivant un protocole rigoureux : Les mesures sont effectuées sur un support parfaitement caractérisé en transmission pour réduire les incertitudes sur la phase lors des mesures en réflexion. Les signaux THz réfléchis aux interfaces entre l'air / échantillon, air / fenêtre, eau / fenêtre et fenêtre / fenêtre sont utilisés comme signal de base pour estimer et améliorer le rapport signal-bruit dans les mesures de spectroscopie. L'avantage de cette méthode est sa précision, sa simplicité et sa facilité d'application pour un système de réflexion avec un angle d'incidence. La mesure des indices de réfraction et des coefficients d'absorption des échantillons avec des tissus tumoraux et sains a révélé que les régions tumorales présentent des différences significatives par rapport au tissu normal lors de l’interaction tissu-rayonnement térahertz.Section II :La deuxième partie de cette étude porte sur l'imagerie THz pour la détection du cancer du sein, à la fois dans les modes de transmission et de réflexion. Plusieurs types d'échantillons ont été étudiés. Les coupes utilisées comprenaient des tissus inclus en paraffine, des tissus frais sortis du bloc opératoire, fixés au formol et des blocs. Pour cela le spectromètre a été déplacé à l'hôpital. Plus de 50 échantillons ont été ainsi inspectés. TroisIVméthodes de traitement d'image ont été utilisées : le découpage, l'automatisation et le tri d'images manuel. De plus, les images obtenues dans le domaine temporel et dans le domaine fréquentiel ont été analysées pour décrire et identifier les différentes régions du tissu mammaire étudiées et déterminer le contraste entre le tissu sain et le tissu malade. La quantité d'eau différentielle présente dans les tissus malades peut être l'une des origines de contraste. En effet, le tissu cancéreux possède une teneur en eau plus élevée que celle des fibres ou des tissus adipeux normaux, ce qui permet de discriminer les régions cancéreuses, fibreuses et graisseuses sur les images THz
The work of this thesis consists in developing terahertz spectroscopy and imaging tools for medical applications. The goal is to determine the potential and effectiveness of terahertz spectroscopy and imaging in the detection of cancer regions and the distinction between diseased and healthy tissue for breast cancer in women. Terahertz spectroimaging is a non-contact, non-ionizing technique for rapid results compared to standard clinical analysis. Experimental studies are divided into two main sections:Section IThis part focuses on THz spectroscopy using THz radiation. The mastery of this technique makes it possible to work in reflection or transmission mode with frequencies in the terahertz bandwidth. Several types of materials have been used as ghosts for the calibration of the experiment: solids (silica, teflon, sapphire and glass), liquids (methanol, water and alcohol) and biological tissues (cancer, fiber and fat), as well as a mixture (water-methanol). The refractive indices, the absorption coefficients and the complex dielectric functions were first measured and extracted and then fitted with a Debye model. Biological tissues have appeared heterogeneous in thickness and with surfaces that may be irregular, making it difficult to extract accurate information because of induced artifacts. The signals have been processed according to a rigorous protocol: The measurements are carried out on a perfectly characterised substratet in transmission to reduce the uncertainties on the phase during the measurements in reflection. The THz signals reflected at the interfaces between the air / sample, air / window, water / window and window / window are used as a basic signal to estimate and improve the signal-to-noise ratio in the spectroscopy measurements. The advantage of this method is its accuracy, simplicity and ease of application for a reflection system with an angle of incidence. Measurement of refractive indices and absorption coefficients of samples with tumor and healthy tissue revealed that the tumor regions showed significant differences from normal tissue during terahertz tissue-radiation interaction.Section II:The second part of this study focuses on THz imaging for breast cancer detection in both transmission and reflection modes. Several types of samples have been studied. Sections used included paraffin-embedded tissue, fresh tissues removed from the OR, formalin-fixed, and blocks. For this the spectrometer has been moved to the hospital. More than 50 samples were inspected. Three image processing methods were used: cutting, automation and manual image sorting. In addition, time domain and frequency domain images were analyzed to describe and identify the different regions of mammary tissue studied and to determine the contrast between healthy tissue and diseased tissue. The amount of differential water present in diseased tissue can be one of the sources of contrast. In fact, the cancerous tissue has a higher water content than that of normal fibers or adipose tissue, which makes it possible to discriminate the cancerous, fibrous and fatty regions on the THz images

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Wachsmuth, Matthew George. „Measurement and Characterization of Terahertz Radiation Propagating Through a Parallel Plate Waveguide“. PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/317.

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As the amount of study into the terahertz (THz) region of the electromagnetic spectrum steadily increases, the parallel plate waveguide has emerged as a simple and effective fixture to perform many experiments. The ability to concentrate THz radiation into a small area or volume enables us to analyze smaller samples and perform more repeatable measurements, which is essential for future research. While the fundamental physics of PPW transmission are understood mathematically, the practical knowledge of building such a fixture for the THz domain and taking measurements on it with a real system needs to be built up through experience. In this thesis, multiple PPW configurations are built and tested. These include waveguides of different lengths and opening heights, using lenses and antennas to focus and collect radiation from the input and output, and different amounts of polish on the waveguide surface. A basic resonator structure is also built and measured as a proof of concept for future research. The two most useful propagation modes through the waveguide, the lowest order transverse magnetic (TEM) and transverse electric (TE) modes, were characterized on all of the setups. Additionally, a flexible fixture was designed and measured which will allow future work in the THz field to be much more reliable and repeatable.

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Sikharin, Suphakul. „Development of Compact Accelerator-Based Terahertz Radiation Source at Kyoto University“. Kyoto University, 2017. http://hdl.handle.net/2433/228250.

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Larsen, Mads Jacob Hedegaard. „Non-Contact Probes for Characterization of THz Devices and Components“. Wright State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=wright1369393504.

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Vieille, Grosjean Mélissa. „Atomes de Rydberg : Étude pour la production d'une source d'électrons monocinétique. Désexcitation par radiation THz pour l'antihydrogène“. Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS349/document.

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Depuis les années 1975, les atomes de Rydberg sont étudiés et maintenant utilisés en information quantique pour leurs propriétés particulières d’interaction. Cependant, ces objets physiques peuvent se retrouver impliqués dans différentes autres applications, où leurs caractéristiques remarquables en font de parfaits outils. Dans ce mémoire, nous nous intéresserons à deux applications distinctes faisant intervenir des atomes de Rydberg de césium. Tout d’abord, nous verrons comment utiliser de tels atomes pour produire une source d’électrons monocinétiques, grâce au mécanisme d’ionisation singulier de ce type d’atomes à une valeur précise de champ électrique dépendante du niveau d’excitation. Les électrons ainsi produits sont ensuite extraits et leur dispersion en énergie mesurée. On montrera notamment de façon théorique et d’après les premières mesures expérimentales réalisées pendant la thèse, que l’on peut espérer obtenir une dispersion en énergie des électrons produits par cette technique de l’ordre du meV, résolution jamais atteinte à ce jour. Ce type de source devient aujourd’hui un outil indispensable pour accéder à la mise au point et l’étude de nouveaux matériaux par contrôle de réactions chimiques à l’échelle moléculaire, et à la cartographie des phonons. Dans un second temps, nous verrons qu’il est possible de désexciter un nuage d’atomes de Rydberg de niveaux variés grâce à une source externe dans le domaine térahertz. Ce projet s’inscrit dans le cadre des expériences d’étude de l’antimatière menées actuellement au CERN, qui visent à élucider le mystère de l’asymétrie matière/antimatière. Les méthodes actuelles de production de l’antihydrogène, forment des nuages de ces anti-atomes dans différents états de Rydberg. Pour les étudier, il est alors nécessaire de désexciter le plus d’atomes d’antihydrogène possible vers le niveau fondamental. Nous présenterons la méthode envisagée, ainsi que les résultats obtenus expérimentalement sur un dispositif créé pendant la thèse pour montrer la faisabilité de la technique. Ces premiers résultats montrent qu’il est possible d’accélérer la désexcitation d’un atome de Rydberg sur un état très élevé grâce à une lampe se comportant comme un corps noir. Nous détaillerons les améliorations envisagées, en particulier pour adapter le spectre des fréquences THz à utiliser et empêcher la photoionisation des atomes, par des filtres ou par le façonnage spectral via l’utilisation d’un photomixer
Since 1975, Rydberg atoms have been studied and now used in quantum information for their particular interaction properties. However, these physical objects can be involved in various other applications, where their remarkable characteristics make them perfect tools. In this paper, we will focus on two distinct applications involving cesium Rydberg atoms. First, we will see how to use such atoms to produce a source of monocinetic electrons, thanks to the singular ionization mechanism of this type of atoms at a precise value of electric field dependent on the excitation level. The electrons thus produced are then extracted and their energy dispersion measured. Theoretically and according to the first experimental measurements made during the thesis, we will show that we can hope an energy dispersion of the electrons produced by this meV technique, a resolution never reached before. Today, this type of source is becoming an indispensable tool for the development and study of new materials by molecular scale chemical reaction control and for phonon mapping. In a second step, we will see that it is possible to de-energize a cloud of Rydberg atoms of various levels thanks to an external source in the tera-hertz domain. This project is part of the ongoing anti-matter experiments at CERN, which aim to unravel the mystery of the matter/anti-matter asymmetry. The current methods of production of antihydrogen, forms clouds of these anti-atoms in different Rydberg states. To study them, it is then necessary to de-energize as many antihydrogen atoms as possible to the fundamental level. We will present the method envisaged, as well as the results obtained experimentally on a device created during the thesis to show the feasibility of the technique. These first results show that it is possible to accelerate the deenergization of a Rydberg atom on a very high state thanks to a lamp behaving like a black body. We will detail the improvements envisaged, in particular to adapt the spectrum of the THz frequencies to use and prevent the photoionization of atoms, by filters or by spectral shaping via the use of a photomixer

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Pallas, Florent. „Etude théorique et expérimentale du fonctionnement bifréquence de microlasers continus et impulsionnels pour la génération d'ondes RF et THz“. Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00877894.

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Parmi les approches possibles pour réaliser des sources térahertz dans la gamme0,2 - 2 THz, nous nous sommes intéressés à la voie optoélectronique qui consiste à générerl'onde térahertz par le photomélange de deux ondes lasers à des fréquences optiques. Letravail présenté dans cette thèse concerne l'étude de lasers bi-fréquence capables d'émettreles deux ondes requises simultanément. Nous commençons par développer un modèlethéorique décrivant la compétition de gain entre les modes laser grâce au calcul de différentscoefficients de couplage. Sur le plan expérimental, nous montrons tout d'abord qu'endésalignant légèrement un des miroirs de la cavité laser, il est possible d'obtenir un régimestable d'émission sur deux fréquences pourtant en compétition dans le milieu à gain, ici uncristal dopé néodyme. Nous nous intéressons ensuite au régime impulsionnel et montronsque les impulsions peuvent être synchronisées grâce à l'action d'un laser externe. Enfin, leprocessus de photomélange a été réalisé et des ondes électromagnétiques ont été généréesdans le domaine des radio-fréquences autour de 20 GHz.

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Royal Society (Great Britain). Discussion Meeting. The terahertz gap: The generation of far-infrared radiation and its applications : papers of a discussion meeting held at The Royal Society on 4 and 5 June 2003. London: The Royal Society, 2004.

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Terahertz And Mid Infrared Radiation Generation Detection And Applications Proceedings Of The Nato Advanced Research Workshopon Terahertz And Mid Infrared Radiation. Springer, 2011.

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Buchteile zum Thema "TERAHERTZ (THZ) RADIATION"

Zhang, Xi-Cheng, und Jingzhou Xu. „Terahertz Radiation“. In Introduction to THz Wave Photonics, 1–26. Boston, MA: Springer US, 2009. http://dx.doi.org/10.1007/978-1-4419-0978-7_1.

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Roskos, H. G., T. Pfeifer, H. M. Heiliger, T. Löffler und H. Kurz. „Tunable Coherent THz Radiation Pulses From Optically Excited Bloch Oscillations“. In New Directions in Terahertz Technology, 369–75. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-5760-5_28.

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Mishra, Ajay, Nimish Dixit und Himani Sharma. „Generation of THz Radiation Using Ring Terahertz Parametric Oscillator“. In Springer Proceedings in Physics, 907–9. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-9259-1_208.

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Jo, Seong Jin, und Oh Sang Kwon. „Structure and Function of Skin: The Application of THz Radiation in Dermatology“. In Convergence of Terahertz Sciences in Biomedical Systems, 281–99. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-3965-9_16.

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Shimosato, H., M. Ashida, T. Itoh, S. Saito und K. Sakai. „Ultrabroadband Detection of Terahertz Radiation from 0.1 to 100 THz with Photoconductive Antenna“. In Springer Series in Optical Sciences, 317–23. New York, NY: Springer New York, 2007. http://dx.doi.org/10.1007/978-0-387-49119-6_41.

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Quema, Alex, Gilbert Diwa, Elmer Estacio, Romeric Pobre, Glenda Delos Reyes, Carlito Ponseca, Hidetoshi Murakami, Shingo Ono und Nobuhiko Sarukura. „Terahertz (THz) Pigtail Assembly Utilizing a Lens Duct for Effective Coupling of THz Radiation into Teflon Photonic Crystal Fiber Waveguide“. In Springer Series in Optical Sciences, 293–99. New York, NY: Springer New York, 2007. http://dx.doi.org/10.1007/978-0-387-49119-6_38.

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Bucur-Portase, Robin-Cristian. „The Effects of Terahertz Radiation on the Development of Biological Organisms I: Wheat Seeds“. In IFMBE Proceedings, 483–88. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92328-0_63.

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Tomalia, Donald A. „Early Goddard Contributions Confirming the Dendritic State: Engineering PAMAM Dendrimer CNDPs to Generate CW-Terahertz Radiation Suitable for Molecular, Bio- and Diagnostics Imaging Spectroscopy“. In Computational Materials, Chemistry, and Biochemistry: From Bold Initiatives to the Last Mile, 935–58. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-18778-1_39.

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„THz Radiative Transfer Basics and Line Radiation“. In Terahertz Astronomy, 39–66. CRC Press, 2015. http://dx.doi.org/10.1201/b19111-3.

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„- THz RADIATIVE TRANSFER BASICS AND LINE RADIATION“. In Terahertz Astronomy, 56–83. CRC Press, 2015. http://dx.doi.org/10.1201/b19111-7.

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Nishitani, Junichi, Takeshi Nagashima und Masanori Hangyo. „Terahertz radiation from antiferromagnetic MnO“. In 2011 36th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2011). IEEE, 2011. http://dx.doi.org/10.1109/irmmw-thz.2011.6105017.

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Hannotte, T., M. Lavancier, S. Mitryukovskiy, J.-F. Lampin und R. Peretti. „Terahertz radiation confinement using metallic resonators“. In 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz). IEEE, 2019. http://dx.doi.org/10.1109/irmmw-thz.2019.8873795.

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Zhang, W.-D., L. Viveros und E. R. Brown. „Concentration of terahertz radiation for microsample spectroscopy“. In 2014 39th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz). IEEE, 2014. http://dx.doi.org/10.1109/irmmw-thz.2014.6956297.

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Li, D., Y. Wang, M. Nakajima, M. Hashida, Y. Wei, S. Miyamoto und M. Tani. „Terahertz radiation from graphene surface plasmon polaritons“. In 2016 41st International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz). IEEE, 2016. http://dx.doi.org/10.1109/irmmw-thz.2016.7758931.

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Drexler, C., J. Karch, P. Olbrich, M. Fehrenbacher, M. M. Glazov, S. A. Tarasenko, D. Weiss et al. „Terahertz radiation induced edge currents in graphene“. In 2011 36th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2011). IEEE, 2011. http://dx.doi.org/10.1109/irmmw-thz.2011.6105064.

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Sasa, S., M. Tatsumi, Y. Kinoshita, M. Koyama, T. Maemoto, I. Kawayama und M. Tonouchi. „Enhanced Terahertz Radiation from GaSb/InAs Heterostructures“. In 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2018). IEEE, 2018. http://dx.doi.org/10.1109/irmmw-thz.2018.8510477.

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Gong, Sen, Fenxiao Dong, Hu Min, Renbin Zhong und Shenggang Liu. „Terahertz Radiation from Graphene Based Hyperbolic Medium“. In 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2018). IEEE, 2018. http://dx.doi.org/10.1109/irmmw-thz.2018.8510482.

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Perucchi, A., L. Capasso, S. Di Mitri, P. Di Pietro, F. Giorgianni, S. Lupi, C. Svetina et al. „THz coherent transition radiation at TeraFERMI: First characterization of THz radiation and electron beam dynamics“. In 2016 41st International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz). IEEE, 2016. http://dx.doi.org/10.1109/irmmw-thz.2016.7758440.

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Frolov, Nikita S., Semen A. Kurkin, Alexey A. Koronovskii und Alexander E. Hramov. „Nanovircator: Promising THz electromagnetic radiation source“. In 2015 40th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz). IEEE, 2015. http://dx.doi.org/10.1109/irmmw-thz.2015.7327630.

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Knap, W., N. Dyakonova, D. Coquilliat, D. But und F. Teppe. „A Terahertz plasma oscillations in nanometer field effect transistors for Terahertz radiation rectification“. In 2013 38th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2013). IEEE, 2013. http://dx.doi.org/10.1109/irmmw-thz.2013.6665746.

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