Dissertations / Theses on the topic 'Terahertz time-domain spectroscopy system'
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Ait, Assou Manal. "Synthetic aperture imaging and spectroscopy in the terahertz range using time domain spectroscopy system." Electronic Thesis or Diss., Limoges, 2024. https://aurore.unilim.fr/theses/nxfile/default/437c1676-13e9-4b65-9ff5-95b93ac02ca3/blobholder:0/2024LIMO0008.pdf.
Les techniques d'imagerie et de spectroscopie térahertz offrent de vastes applications dans le control non destructif ou le contrôle de qualité dans la manufacture industrielle, la pharmaceutique et la biologie, l'archéologie ou encore le monde de l’art. Pour ces applications, la technique de spectroscopie térahertz dans le domaine temporel (THz-TDS) permet une analyse sur une bande passante instantanée très large (0.1-6 THz), mais nécessite généralement de déplacer mécaniquement l’échantillon à imager dans le plan focal du faisceau THz. Le travail de cette thèse porte sur l’adaptation d’un banc THz-TDS pour l’imagerie et la spectroscopie des échantillons fixes, en se basant sur le principe d’un radar à synthèse d’ouverture (SAR), en transmission. En utilisant cette technique, on démontre une reconstruction d'image en 3D avec une résolution inférieure au millimètre de plusieurs échantillons différents. Pour remédier au temps d'acquisition prolongés, un échantillonnage spatial lacunaire est proposé, réduisant les éléments du réseau synthétique et améliorant la vitesse d'acquisition. De plus, les données reconstruites ne sont pas uniquement utilisées pour l'imagerie mais permettent également la caractérisation des paramètres optiques matériaux (l'indice de réfraction et le coefficient d'absorption) constituant l'objet imagé dans la bande de fréquence de reconstruction. Ainsi, la technique proposée permet la cartographie spectrale 2D de l'indice de réfraction à diverses fréquences térahertz. Enfin, la méthodologie proposée est appliquée à l'imagerie de sortie de guide d'ondes térahertz, illustrant sa grande flexibilité et ses vastes domaine potentielles d’utilisation
Theuer, Michael. "Terahertz time-domain spectroscopy systems for fundamental and industrial applications." Göttingen Cuvillier, 2008. http://d-nb.info/996276696/04.
Yeng, Zang. "A fundamental critical assessment of efficiencies in terahertz time-domain spectroscopy systems." Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/24855.
Bockelt, Alexander Stefan. "Fiber-based Terahertz Time-Domain Spectroscopy Systems Operated in the Telecom Band." Doctoral thesis, Universitat Politècnica de València, 2017. http://hdl.handle.net/10251/86148.
El objetivo de la presente Tesis Doctoral es el estudio de espectroscopios temporales de Terahercios basados en tecnología de fibra óptica para telecomunicaciones. La fibra óptica ofrece bajas pérdidas de propagación, alta estabilidad y la capacidad de implementar sistemas robustos y compactos, características que facilitan el despliegue de este tipo de instrumentos de sensado en escenarios industriales. El desarrollo de fuentes de THz que operan en la banda infrarroja empleada en telecomunicaciones permite el uso de componentes maduros de la industria de las comunicaciones ópticas, lo que a su vez se ha traducido en una transición desde el uso de la banda de THz básicamente para intereses científicos al desarrollo de sistemas para aplicaciones industriales. En la presente tesis se investigan sistemas de THz basados en antenas fotoconductivas y fibra óptica a distintos niveles: control de la estructura fotoconductiva, instrumento y sistema. El transporte de portadores en heteroestructuras multicapa InGaAs-InAlAs, empleadas actualmente en antenas fotoconductivas, se ha investigado bajo la inyección de una onda óptica continua. Se ha observado que variando el nivel de amplitud de esta onda continua tanto en el emisor como en el receptor es posible controlar la fotocorriente detectada sin afectar a su ancho de banda. A diferencia de un incremento en la potencia óptica de la señal pulsada, elevar el nivel de continua resulta en una reducción de la fotocorriente medida. Esta reducción de la conductividad se relaciona con cambios en el tiempo de relajación del momento de los portadores en el material fotoactivo en lugar de variaciones de la densidad de portadores libres. Este comportamiento puede tener un efecto en sistemas que introduzcan componentes ópticos continuos como por ejemplo sistemas de sensado que empleen amplificadores ópticos. Este efecto puede ser usado para modular las condiciones de operación de las antenas fotoconductivas permitiendo el control todo-óptico del sistema. Este método permite modular la señal, lo que resulta necesario por ejemplo para realizar detección lock-in. Tanto diferentes aplicaciones industriales como los sistemas de imagen en THz requieren sistemas rápidos de captura. Para ello es necesario sustituir las líneas de retardo ópticas tradicionales basadas en motores paso-a-paso por otros sistemas de mayor velocidad. Se ha implementado y caracterizado un sistema THz-TDS usando una línea de retardo rápida basada en bobinas de voz. Una característica fundamental de la fibra óptica es su extraordinaria simplicidad para realizar la distribución de señales ópticas. Esta característica puede ser explotada para permitir la operación centralizada de un conjunto paralelo de sensores de THz. Una arquitectura centralizada en la que la fuente óptica se comparte entre muchos sensores simplifica la implementación y reduce el coste de sistemas de inspección no destructiva que requieran de múltiples sensores en paralelo, como, por ejemplo, en control de calidad industrial o en controles de seguridad. Se ha evaluado el coste de estos sistemas distribuidos, se ha validado experimentalmente su viabilidad y se han identificado y estudiado sus prestaciones. El documento de la tesis doctoral se estructura formalmente en una breve introducción, el capítulo 2, en el que se revisa la tecnología de THz en su conjunto, los esquemas optoelectrónicos y el uso de tecnologías ópticas basadas en la banda de las telecomunicaciones. El capítulo 3 incluye el estudio realizado sobre la dinámica de los portadores bajo la irradiación dela antena fotoconductiva con una onda óptica continua y su uso como técnica de modulación. El capítulo 4 trata con la implementación de un sistema THz-TDS rápido mientras que el capítulo 5 describe y analiza una arquitectura de sensado paralela para reducir costes. Finalmente el capítulo 6 recoge las conclusiones y futuras líneas de actuación.
L'objectiu de la present Tesi Doctoral és l'estudi d'espectroscopis temporals de terahertzs basats en tecnologia de fibra òptica per a telecomunicacions. La fibra òptica ofereix baixes pèrdues de propagació, alta estabilitat i la capacitat d'implementar sistemes robustos i compactes, característiques que faciliten el desplegament d'aquest tipus d'instruments de sensat en escenaris industrials. El desenvolupament de fonts de THz que operen a la banda infraroja emprada en telecomunicacions permet l'ús de components madurs de la indústria de les comunicacions òptiques, el que al seu torn s'ha traduït en una transició des de l'ús de la banda de THz bàsicament per interessos científics al desenvolupament de sistemes per a aplicacions industrials. En la present tesi s'investiguen sistemes de THz basats en antenes fotoconductivas i fibra òptica a diferents nivells: control de l'estructura fotoconductiva, instrument i sistema. El transport de portadors en heteroestructures multicapa InGaAs-InAlAs, emprades actualment en antenes fotoconductivas, s'ha investigat sota la injecció d'una ona òptica contínua. S'ha observat que variant el nivell d'amplitud d'aquesta ona contínua tant en l'emissor com en el receptor és possible controlar la fotocorriente detectada sense afectar el seu ample de banda. A diferència d'un increment en la potència òptica del senyal polsada, elevar el nivell de contínua resulta en una reducció de la fotocorrent mesurada. Aquesta reducció de la conductivitat es relaciona amb canvis en el temps de relaxació del moment dels portadors en el material fotoactiu en lloc de variacions de la densitat de portadors lliures. Aquest comportament pot tenir un efecte en sistemes que introdueixin components òptics continus com ara sistemes de sensat que utilitzen amplificadors òptics. Aquest efecte pot ser usat per modular les condicions d'operació de les antenes fotoconductivas permetent el control tot-òptic del sistema. Aquest mètode permet modular el senyal, el que resulta necessari per exemple per realitzar detecció lock-in. Tant diferents aplicacions industrials com els sistemes d'imatge en THz requereixen sistemes ràpids de captura. Per a això és necessari substituir les línies de retard òptiques tradicionals basades en motors pas-a-pas per altres sistemes de major velocitat. S'ha implementat i caracteritzat un sistema THz-TDS usant una línia de retard ràpida basada en bobines de veu. Una característica fonamental de la fibra òptica és la seua extraordinària simplicitat per realitzar la distribució de senyals òptiques. Aquesta característica pot ser explotada per a permetre l'operació centralitzada d'un conjunt paral·lel de sensors de THz. Una arquitectura centralitzada en la qual la font òptica es comparteix entre molts sensors simplifica la implementació i redueix el cost de sistemes d'inspecció no destructiva que requereixin de múltiples sensors en paral·lel, com, per exemple, en control de qualitat industrial o en controls de seguretat . S'ha avaluat el cost d'aquests sistemes distribuïts, s'ha validat experimentalment la seua viabilitat i s'han identificat i estudiat les seues prestacions. El document de la tesi doctoral s'estructura formalment en una breu introducció, capítol 2, en el qual es revisa la tecnologia de THz en el seu conjunt, els esquemes optoelectrònics i l'ús de tecnologies òptiques basades en la banda de les telecomunicacions. El capítol 4 inclou l'estudi realitzat sobre la dinàmica dels portadors sota la irradiació de la antena fotoconductiva amb una ona òptica contínua i el seu ús com a tècnica de modulació. El capítol 5 tracta la implementació d'un sistema THz-TDS ràpid mentre que el capítol 6 descriu i analitza una arquitectura de sensat paral·lela per reduir costos. Finalment, el capítol 7 recull les conclusions i futures línies d'actuació.
Bockelt, AS. (2017). Fiber-based Terahertz Time-Domain Spectroscopy Systems Operated in the Telecom Band [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/86148
TESIS
Nandi, Uttam [Verfasser], Sascha [Akademischer Betreuer] Preu, and Clara [Akademischer Betreuer] Saraceno. "ErAs:In(Al)GaAs photoconductors for 1550 nm-based Terahertz time domain spectroscopy systems / Uttam Nandi ; Sascha Preu, Clara Saraceno." Darmstadt : Universitäts- und Landesbibliothek, 2021. http://d-nb.info/124124832X/34.
Bičiūnas, Andrius. "Semiconductor materials for components of optoelectronic terahertz systems activated by femtosecond 1 µm wavelength laser pulses." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2012. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2012~D_20121107_091148-13422.
Disertacijos darbo tikslas buvo sukurti ir ištirti puslaidininkinius terahercinių (THz) impulsų emiterius ir detektorius, skirtus sistemoms, naudojančioms 1 μm bangos ilgio femtosekundinę lazerinę spinduliuotę. THz impulsų generavimo ir detektavimo sistema, kurios optoelektroninius puslaidininkinius komponentus aktyvuoja femtosekundiniai lazerio impulsai, yra plačiai taikoma terahercinėje laikinės srities spektroskopijoje. Tradiciškai tokiose sistemose naudojami Ti:safyre femtosekundiniai lazeriai, kurių spinduliuotės bangos ilgis yra ~800 nm. Šios sistemos nėra patogios dėl jų matmenų, nes lazeriai turi sudėtingą kelių pakopų kaupinimo sistemą. Pastaruoju metu THz impulsų generavimui vis dažniau naudojami femtosekundiniai kietakūniai ir šviesolaidiniai lazeriai, kurių spinduliuotės bangos ilgis patenka į artimosios IR spinduliuotės sritį. Tačiau šios sistemos vis dar neturi tinkamos medžiagos fotolaidiems elementams gaminti, kurie būtų žadinami 1 – 1,55 µm bangos ilgio lazeriais. Tokios medžiagos, visų pirmą, turi būti jautrios optinei spinduliuotei, o jų draustinės energijos tarpas turi atitikti žadinamos spinduliuotės fotonų energiją, be to sluoksniai turi pasižymėti didele tamsine varža bei labai trumpomis krūvininkų gyvavimo trukmėmis (~ 1 ps). Šioje disertacijoje yra pateikiami THz impulsų generavimo panaudojus puslaidininkių paviršius ir fotolaidžias antenas rezultatai, žadinant 1 µm bangos ilgio femtosekundiniais lazerio impulsais.
Skjeie, Hans Christian Bakken. "Terahertz Time-Domain Spectroscopy." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elektronikk og telekommunikasjon, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19214.
Hussain, Ali. "Ultrabroadband time domain terahertz spectroscopy." Thesis, University of Bath, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431734.
Torcedo, Jojit Camama. "Time-domain Terahertz Spectroscopy of water." Diss., [Riverside, Calif.] : University of California, Riverside, 2010. http://proquest.umi.com/pqdweb?index=0&did=2019861181&SrchMode=2&sid=1&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1274284155&clientId=48051.
Includes abstract. Title from first page of PDF file (viewed May 18, 2010). Includes bibliographical references. Issued in print and online. Available via ProQuest Digital Dissertations.
Camus, Enrique Castro. "Polarisation resolved terahertz time domain spectroscopy." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441048.
Graber, Benjamin. "HIGH POWER TIME DOMAIN TERAHERTZ SPECTROSCOPY." Diss., Temple University Libraries, 2014. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/301211.
Ph.D.
Terahertz (THz) has become a strong area for scientific research and commercial application in recent years. This research group has redesigned and optimized a THz photoconductive antenna, which currently operates with approximately 10x the power of a commercial antenna. It has been determined by this research that the THz signal emitted from a photoconductive antenna consists of coherent and incoherent signals. In addition to the improvement of the THz photoconductive antenna, I have optimized an electro optic THz detection system by characterizing the field dependency of an electro optic crystal, which enabled me to estimate the THz electric field strength. The high power THz source and optimized detection system were combined into a high power, high resolution time domain THz spectrometer. This spectrometer was used to conduct original measurements of the THz spectrum of water vapor, ionized air, and various chemical vapor including explosives. Most of these measurements were only possible with our improved THz spectrometer. In order to understand ionized air, an additional study was carried out to explore the ionization of several gases (e.g. N2, O2, Ar, CO2, and water vapor) which were ionized by radioactive isotopes. This unique study found that in addition to dose rate, the gamma energy of the radioactive isotopes and the sequential ionization levels of gases affect the equilibrium ion densities of these gases. This effect was especially pronounced for argon gas. The study of ion dynamics in gases has lead to the development of a prototype for stand-off detection and identification of radioactive isotopes. This prototype, despite being simple in design, can detect isotopes faster and more cheaply than a conventional gamma ray spectrometer. Throughout this thesis research I have successfully developed a high power, high resolution terahertz spectrometer and demonstrated that with the spectrometer I could identify characteristic resonances of water vapor, some chemicals including explosives, and even ionized air produced by nuclear isotopes. From the characteristic resonance frequencies one can understand the underlying physics or chemistry of molecules or atoms.
Temple University--Theses
Koseoglu, Devrim. "Material Characterization With Terahertz Time-domain Spectroscopy." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/2/12611648/index.pdf.
110>
crystals of various thicknesses to test the applicability of this algorithm. We have shown that the algorithm developed provides a quick way of eliminating the &ldquo
etalon&rdquo
reflections from the data. In addition, it is also shown that these &ldquo
etalon&rdquo
effects can be used for the frequency calibration of terahertz time-domain spectrometers.
Tych, Katarzyna Maria. "Terahertz time-domain spectroscopy of biological macromolecules." Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.540584.
Chung, A. L. "Material parameter extraction in terahertz time domain spectroscopy." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/352056/.
Moore, Graeme Patrick. "Time domain terahertz electro- and magneto-optic spectroscopy." Thesis, University of Bath, 2001. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392059.
Peter, F. "Advanced emitters and detectors for terahertz time-domain spectroscopy." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-61479.
Lloyd-Hughes, James. "Terahertz time-domain spectroscopy of carrier trapping in semiconductors." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437186.
Schiff-Kearn, Aidan. "Experimental and Numerical Investigations into Terahertz Time-Domain Spectroscopy." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/38708.
Smith, Ryan Michael. "Terahertz frequency analysis of gaseous and solid samples using terahertz time-domain spectroscopy." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/3386.
Karaoglan, Gulten. "Investigation Of Dc Generated Plasmas Using Terahertz Time Domain Spectroscopy." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12612070/index.pdf.
Wheatcroft, Justin C. "Terahertz time domain spectroscopy and Fresnel coefficient based predictive model." Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1347483587.
Bandaranayake, B. M. Bimali S. "Terahertz time domain spectroscopy (THz-TDS) for solid state analysis." Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/3046.
Upadhya, Prasanth Chandrashekara. "Coherent generation and detection of Terahertz radiation : time domain Terahertz spectroscopy of molecular crystals." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614771.
Koral, Can. "Experimental Investigation Of Nanofluids Using Terahertz Time Domain Spectroscopy (thz Tds)." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614424/index.pdf.
Pan, Yi. "Terahertz time-domain spectroscopy and near-field imaging of microstructured waveguides." Thesis, University of Bath, 2013. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607613.
Hissen, Huzifa Zain Alabdeen Abdarahman. "Spectral characterization of materials using terahertz time domain spectroscopy (THz-TDS)." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/96030.
ENGLISH ABSTRACT: Terahertz (THz) radiation is often used in many promising applications such as information and communication technology and airport security. Optimized and adapted terahertz fields hold huge promise for leading this technology further. This study is focused on terahertz time domain spectroscopy (THz-TDS). In THz-TDS the electric field is measured, therefore both amplitude and phase information of the THz pulse can be obtained. We used the pump-probe technique in order to measure a THz pulse from the photoconductive antenna. A pulsed fiber laser with FWHM of ' 100 fs was used for this. The frequency spectrum of the measured THz pulse was obtained via a fast Fourier transform. We studied the principles of the THz pulse generation as well as detection, with a photoconductive antenna as emitter and detector. In this study terahertz spectroscopy has been used to investigate the refractive index and absorption coefficient of different types of materials in the terahertz region. The last part of this study deals with a simple process for material parameter extraction of a polymer sample using commercial software called Teramat1.0. It uses the sample thickness, the reference THz pulse and the transmitted THz pulse to retrieve the complex refractive index of the sample.
AFRIKAANSE OPSOMMING: Terahertz (THz) straling word gereeld gebruik vir belowende toepassings soos inligting en kommunikasie tegnologie en lughawe sekuriteit. Geoptimeerde en aangepaste terahertz velde dra by tot die bevordering van die tegnologie. Hierdie studie fokus op terahertz tyd domein spektroskopie (THz-TDS). In THz-TDS word die elektriese veld gemeet en dus word beide amplitude en fase inligting van die THz puls verkry. Ons gebruik ’n pomp en toets tegniek om die THz puls deur ’n fotogeleidende antenna te bepaal. ’n Gepulseerde vesel laser met FWHM van 100 fs word hiervoor benut. Die frekwensie spektrum van die gemete THz puls word bereken deur ’n vinnige Fourier transvorm te bereken. Die beginsels van die generering en deteksie van THz pulse is bestudeer met ’n fotogeleidende antenna as sender en ontvanger. In die studie is terahertz spektroskopie gebruik om die brekingsindekse en die absorpsie koeffisiënte van verskillende materiale in die terahertz gebied te bepaal. Die laaste gedeelte van die studie handel oor ’n eenvoudige proses om die materiaal parameters van ’n polimeer te bepaal deur gebruik te maak van kommersiële sagteware Teramat 1.0. Die monster dikte, die THz verwysingspuls en die deurgelate puls word gebruik om die komplekse brekingsindeks van die materiaal te bereken.
Li, Ruoyu. "Hydrogen bonding structure and dynamics studied by terahertz time-domain spectroscopy." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648484.
Xia, Chen. "Terahertz Time-Domain Spectroscopy of Low-Dimensional Materials and Photonic Structures." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1355168322.
Taulbee, Anita R. "Terahertz Time-Domain Spectroscopy and Imaging of Biological Compounds and Tissues." Miami University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=miami1249412289.
Metbulut, Mukaddes Meliz. "Development Of Compact Terahertz Time-domain Terahertz Spectrometer Using Electro-optic Detection Method." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610983/index.pdf.
Smith, Shane Raymond. "Construction and characterization of a multi-antenna terahertz time-domain spectroscopy setup." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96733.
ENGLISH ABSTRACT: Recent progress in laser and semiconductor technology has allowed for far easier generation and measuring of coherent terahertz radiation, a previously difficult region in the radiation spectrum to coherently generate. Time based terahertz spectroscopy is a rather unique form of spectroscopy. Not only is it time based, but the electric field is measured instead of the intensity. This allows for the measurement of the complex refractive index. From this one can obtain certain details of the structure and environment of the sample being studied. A terahertz time-domain spectroscopy setup was constructed during this project. This setup used low temperature grown GaAs photoconductive antennae, with multiple antenna size options available for both the receiving and transmitting antennae. After the construction and alignment of this setup, the antennae were characterized. Lastly measurements were performed on the background, sugar and silicon to demonstrate the capabilities of the system. It was found that the measured terahertz electric field amplitude increased with the intensity of the pump pulse and that the amplitude of the measured terahertz electric field was dependent on the polarization of the pump pulse. As the size of the antenna was increased so too did the amplitude of the measured electric field and conversely the bandwidth of the measured terahertz electric field decreased with the increase of antenna size. This held true for both the transmitting and receiving antennae.
AFRIKAANSE OPSOMMING: Danksê onlangse tegnologiese onwikkelings in lasers en halfgeleier het dit veel makliker geraak om terahertz straling te genereer wat fase samehangendheid toon. Voor hierdie ontwikkelings was straling in hierdie spektrale gebied moeilik om te genereer op ’n wyse wat fase samehangendheid toon. Tyd verwante terahertz spektroskopie is taamlik uniek, aangesien die metings in tyd geneem word en die elektriese veld amplitude word pleks van die intensiteit gemeet. Een van die voordele van hierdie metode is dat dit toelaat vir die meeting van die komplekse brekingsindeks van monsters. Dit is moontlik om van die komplekse brekingsindeks strukturele en omgewings eienskappe van die monster af te lei. Gedurende die projek was ’n tyd verwante terahertz spektroskopie sisteem gebou wat gebaseer was op lae temperatuur gegroeide GaAs foto-geleidende antennas. Die sisteem bevat vier antennas van verskillende groottes aan beide die sender en ontvanger kant. Die antennas was gekarakteriseer na die bou en belyning van die terahertz sisteem en meetings was gedoen op die agtergrond, suiker en silikon om die sisteem se vermoë te demonstreer. Dit was gevind dat die amplitude van die gemete terahertz elektriese veld groter geraak het soos die intensiteit van die pomp puls verhoog was en dat die die amplitude van die gemete terahertz electriese veld afhanklik was van die polarisasie van die pomp puls. Die amplitude van van die gemete terahertz elektriese veld het gegroei met die grootte van die antenna, maar hoe groter die antenna geraak het, hoe kleiner was die bandwydte van die gemete terahertz elektriese veld. Hierdie was die geval vir beide die sender en ontvanger antennas.
Glancy, Paul Michael. "Terahertz time domain spectroscopy (THz-TDS) of hydrated biomolecular polymers and monomers." Diss., UC access only, 2009. http://proquest.umi.com/pqdweb?index=153&did=1906549291&SrchMode=1&sid=1&Fmt=7&retrieveGroup=0&VType=PQD&VInst=PROD&RQT=309&VName=PQD&TS=1270496277&clientId=48051.
Vita. Includes abstract. Includes bibliographical references (leaves 148-155). Issued in print and online. Available via ProQuest Digital Dissertations.
Smith, William. "Development of techniques for magneto-spectroscopy at terahertz frequencies." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/development-of-techniques-for-magnetospectroscopy-at-terahertz-frequencies(b9445541-8050-4f9b-9b1f-6a2d0c2935c3).html.
Hufnagle, David C. "THE ANALYSIS OF BIOLOGICAL COMPOUNDS AND THREAT AGENTS WITH TERAHERTZ TIME-DOMAIN SPECTROSCOPY AND IMAGING." Miami University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=miami1354282849.
Yu, Yiran. "Measurement of Coating Thickness Based on Terahertz Time-Domain Spectroscopy (THz-TDS) Technology." Thesis, KTH, Fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231335.
Jasper, Evan. "Development of Techniques in Time Domain Terahertz Spectroscopy for the Study of Chiral and Topological Materials." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1597048083501651.
Niklas, Andrew John. "Highly-Configurable Multi-Objective Optimization for Physical Parameter Extraction using Terahertz Time-Domain Spectroscopy." Wright State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=wright1527270199110387.
Yahyapour, Milad [Verfasser]. "A Fast, Flexible, and Compact Terahertz Time-Domain System / Milad Yahyapour." Düren : Shaker, 2020. http://d-nb.info/1217164243/34.
Hawecker, Jacques. "Terahertz time resolved spectroscopy of Intersubband Polaritons and Spintronic Emitters." Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS101.
The terahertz (THz) domain provides a rich playground for many practical and fundamental applications, where the low energy of THz photons permits to probe novel light-matter interactions. This work investigates two recent and emerging scientific areas where ultrafast THz spectroscopy can be used as a probe of fundamental phenomena, as well as potentially enabling the conception of new THz sources. In the first case, ultrafast THz spintronics are studied where ultrafast excitations of spintronic heterojunctions result in efficient pulse generation. These structures consist of nanometer thick ferromagnetic - heavy metal junctions, where an optically generated spin-charge in the former is converted to a charge-current in the latter via the Inverse Spin Hall Effect. Beyond these metal-based junctions, ultrafast THz spintronics based on “quantum” materials is also investigated, where THz pulses are generated using quantum phenomena such as the Inverse Edelstein Effect in Topological Insulators, shown to be a promising research direction. The second subject area is focused on THz intersubband polaritons, quasi-particles that emerge from the strong light-matter coupling of a THz photonic cavity and an intersubband transition. Here we are interested in the bosonic nature of the intersubband polaritons, as a long-term aim of realizing a novel THz laser based on Bose-Einstein condensation. In this work, we investigate resonant narrowband pumping of a polariton branch and probe using spectrally broad THz pulses. This shows strong indications of nonlinear effects and potential signatures of scattering processes that could eventually lead to the demonstration of THz polaritonic gain. Finally, to support our work in the above subject areas, technological developments were made in existing THz sources. This included high power THz photoconductive switches using cavities, which permitted the first demonstrations of real time THz imaging with such devices, and high power THz quantum cascade lasers as narrowband laser pumps
Warren, Matthew Timothy. "Time-Domain Terahertz Studies of Strongly Correlated GeV4S8 and Osmate Double-Perovskites." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1512066420271281.
Karlsen, Peter. "Terahertz spectroscopy of charge-carrier dynamics in one-dimensional nanomaterials." Thesis, University of Exeter, 2018. http://hdl.handle.net/10871/33086.
Arik, Enis. "Dielectric Properties Of Fuel Oils And Their Ethanol Mixtures Investigated By Terahertz Time-domain Spectroscopy." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615463/index.pdf.
Khazan, Maxim A. "Time domain terahertz spectroscopy and its application to the study of high-Tc superconductor thin films." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=964408740.
Beck, Matthias [Verfasser]. "Non-Equilibrium Phenomena in Conventional and High-Temperature Superconductors Probed by Time-Domain Terahertz-Spectroscopy / Matthias Beck." München : Verlag Dr. Hut, 2014. http://d-nb.info/1052375502/34.
Rämer, Jan-Martin [Verfasser]. "A Terahertz Time-Domain Spectroscopy-based Vector Network Analyzer Setup with Integrated Pulse Shaping / Jan-Martin Rämer." München : Verlag Dr. Hut, 2016. http://d-nb.info/1097818438/34.
Liang, Qijun [Verfasser]. "Terahertz Time-Domain Spectroscopy : Characterization of Nonlinear Crystals, Nanowires, 2D Gratings,Organic Liquids, and Polystyrene Particles / Qijun Liang." Konstanz : Bibliothek der Universität Konstanz, 2015. http://d-nb.info/1110772335/34.
Maysonnave, Jean. "Dynamique ultrarapide de lasers à cascade quantique Terahertz - le graphène comme émetteur Terahertz." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066360/document.
The terahertz (THz) range is a region of the electromagnetic spectrum which lies at the limit between the electronic and optical domain. Currently, THz applications suffer from the lack of sources and detectors. In this context, this thesis focuses on the fundamental study and the development of new functionalities of different THz sources, usingTHz time-domain spectroscopy (TDS) as a base. This powerful tool enables to acquire the temporal profile of a THz electric field and is used to explore the THz emission properties of quantum cascade lasers (QCLs) and graphene.In the first part, the ultrafast response of QCLs is investigated. A phase control of the electric field of THz QCLs via injection seeding is realised and optimised. This enables the measurement of the amplitude and temporal profile of the laser emission. Throughthese experiments and simulations, a quantitative description of the gain dynamics can be accessed. This information is critical for modelocking. Finally, a fast modulation of the gain of QCLs is realized and leads to short pulses generation (15 ps) in a modelocked regime. These studies open the way for using QCLs as powerful sources in TDS.In the second part, THz radiation generation from graphene under optical excitation is demonstrated by a second order non-linear process. The THz emission results from themomentum transfer from the photons to the electrons of graphene (photon drag). As well as broadband THz generation, novel bandstructure properties of graphene can be explored such as the different dynamics between the photogenerated electrons and holes
Bou, Sleiman Joyce. "Terahertz imaging and spectroscopy : application to defense and security." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0077/document.
The aim of this work is to demonstrate the potential and capabilities of terahertz technology for parcels screening and inspection to detect threats such as weapons and explosives, without the need to open the parcel.In this study, we first present terahertz time-domain spectroscopy and spectral imaging for explosives detection. Two types of explosives as well as their binary mixture is analyzed. Due to the complexity of extracting information when facing such mixtures of samples, three chemometric tools are used: principal component analysis (PCA), partial least square analysis (PLS) and partial least squares-discriminant analysis (PLS-DA). The analyses are applied to terahertz spectral data and to spectral-images in order to: (i) describe a set of unknown data and identify similarities between samples by PCA; (ii) create a classification model and predict the belonging of unknown samples to each of the classes, by PLS-DA; (iii) create a model able to quantify and predict the explosive concentrations in a pure state or in mixtures, by PLS.The second part of this work focuses on millimeter wave imaging for weapon detection in parcels. Three different imaging techniques are studied: passive imaging, continuous wave (CW) active imaging and frequency modulated continuous wave (FMCW) active imaging. The performances, the advantages and the limitations of each of the three techniques, for parcel inspection, are exhibited. Moreover, computed tomography is applied to each of the three techniques to visualize data in 3D and inspect parcels in volume. Thus, a special tomography algorithm is developed by taking in consideration the Gaussian propagation of the wave
Maysonnave, Jean. "Dynamique ultrarapide de lasers à cascade quantique Terahertz - le graphène comme émetteur Terahertz." Electronic Thesis or Diss., Paris 6, 2014. http://www.theses.fr/2014PA066360.
The terahertz (THz) range is a region of the electromagnetic spectrum which lies at the limit between the electronic and optical domain. Currently, THz applications suffer from the lack of sources and detectors. In this context, this thesis focuses on the fundamental study and the development of new functionalities of different THz sources, usingTHz time-domain spectroscopy (TDS) as a base. This powerful tool enables to acquire the temporal profile of a THz electric field and is used to explore the THz emission properties of quantum cascade lasers (QCLs) and graphene.In the first part, the ultrafast response of QCLs is investigated. A phase control of the electric field of THz QCLs via injection seeding is realised and optimised. This enables the measurement of the amplitude and temporal profile of the laser emission. Throughthese experiments and simulations, a quantitative description of the gain dynamics can be accessed. This information is critical for modelocking. Finally, a fast modulation of the gain of QCLs is realized and leads to short pulses generation (15 ps) in a modelocked regime. These studies open the way for using QCLs as powerful sources in TDS.In the second part, THz radiation generation from graphene under optical excitation is demonstrated by a second order non-linear process. The THz emission results from themomentum transfer from the photons to the electrons of graphene (photon drag). As well as broadband THz generation, novel bandstructure properties of graphene can be explored such as the different dynamics between the photogenerated electrons and holes
Bičiūnas, Andrius. "Puslaidininkinių medžiagų, skirtų 1 µm bangos ilgio femtosekundiniais lazerio impulsais aktyvuojamų terahercinių optoelektronikos sistemų komponentams, tyrimas." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2012. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2012~D_20121107_091138-15044.
The aim of dissertation was to develop and explore the semiconductor material terahertz (THz) pulse emitters, for Terahertz time–domain spectroscopy (THz–TDS) systems using a 1 μm wavelength femtosecond laser radiation. THz pulse generation and detection using optoelectronic semiconductor components in THz–TDS excited by femtosecond laser pulses become these days a powerful experimental technique. Traditionally, mode-locked Ti:sapphire lasers emitting at the wavelengths ~800 nm are used. However Ti:sapphire lasers require many-stage optical pumping arrangement, the system is quite bulky and complicated. The solution could be the lasers emitting in 1 – 1.55 µm, which can be directly pumped by diode laser bars. Recently, several compact, efficient and cost-effective solid-state and fiber laser systems that generate femtosecond pulses at near-infrared wavelengths have been developed and employed for activating THz–TDS systems. The main obstacle of these systems is the lack of material with appropriate bandgap, high dark resistivity and short (~ ps) carrier lifetimes.