Dissertations / Theses on the topic 'Sub-THz'
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Tsiatmas, Anagnostis. "Novel approaches in manipulating, guiding, and generating THz and sub-THz fields." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/359886/.
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This thesis serves to address the main challenges of the terahertz technology, providing new efficient ways of actively manipulating, guiding, and generating THz and sub-THz fields. This is accomplished by taking a truly interdisciplinary approach and exploiting the physics of superconductors, and the electrodynamics of metamaterial and plasmonic structures. Metamaterial arrays made of superconducting films are suggested for manipulating the THz radiations, while superconducting plasmonic waveguides are considered for achieving efficient propagation of THz waves. In addition, metamaterial arrays composed of bimetallic rings that exhibit both plasmonic and thermoelectric properties are investigated as a possible new source of THz radiation and strong magnetic fields. I have demonstrated experimentally, for the first time, that high- and low-critical temperature superconducting metamaterials are able to show sub-radiant resonances of Fano type that can be controlled with temperature. Such metamaterial resonances show vanishing radiation losses, while superconductors have very low Ohmic losses. Thus, these structures offer an efficient way to actively manipulate sub-THz (and THz) fields. I have reported on the first experimental realisation of the extraordinary transmission effect in periodically perforated superconducting films. I have shown that the level of transmission of sub-THz waves through these structures could be controlled with temperature near the superconducting transition point. The latter enabled to identify the role of the plasmonic excitations in the mechanism of extraordinary transmission. I have shown that superconductors below their gap-frequency (several THz for high-temperature superconductors) are similar in behaviour to plasmonic metals at optical frequencies. Geometries of superconducting structures have been identified that support almost dispersionless propagation of plasmonic-like modes with frequencies up to several THz, exhibiting both extreme localisation and very low propagation losses. Finally, I have theoretically demonstrated that metamaterial arrays composed of bimetallic gold-nickel nanorings, when illuminated by ultrafast optical pulses, support transient thermoelectric currents that lead to the generation of magnetic pulses of subpicosecond duration, nanoscale localisation and peak amplitudes of the order of one Tesla. These results could facilitate the study of ultrafast nanoscale magnetic phenomena and have potential use in such applications as material characterisation and magnetic recording.
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Dupre, Olivier. "Spectroscopie optique au sub-THz et au sub-Kelvin de supraconducteurs." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAY033/document.
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Dans le cadre de ma thèse, j’ai étudié des supraconducteurs par une nouvelle technique de spectroscopie optique. Cette technique, inspirée de détecteurs de photons utilisés en astrophysique, permet de faire des mesures de 0 à 300 GHz, avec une résolution de ~1 GHz, à une température de ~100 mK. Les supraconducteurs étudiés sont lithographiés sous la forme de résonateurs pour devenir des détecteurs de photons dont leur fréquence de résonance varie en fonction de leur densité superfluide. Au cours de cette thèse, j’ai fabriqué et étudié des résonateurs à partir de différents matériaux supraconducteurs (en couches minces). La dimensionnalité joue un rôle essentiel dans la supraconductivité. A priori, en deux dimensions un système ne devrait pas être supraconducteur mais il existe de nombreux contre-exemples (monocouche de FeSe, interface d’oxydes,…). Dans ce contexte l’aluminium est particulièrement intéressant car le mécanisme supraconducteur est conventionnel (couplage électron-phonon) et que l’on peut faire varier son épaisseur (couches minces) et sa microstructure (aluminium granulaire) relativement facilement. La thèse se compose de deux parties.Dans une première partie je me suis intéressé à l’influence de l’épaisseur sur la supraconductivité de couches minces d’aluminium (de 15nm à 200nm). Dans la majorité des matériaux supraconducteurs, la température critique diminue avec l’épaisseur alors que dans certains matériaux, comme dans l’aluminium, elle augmente. Différentes théories existent pour expliquer ce phénomène mais il n’existe actuellement aucun consensus. Par des techniques combinées de spectroscopie à forte résolution et de résistivité, j’essaye d’apporter un éclairage nouveau à l’augmentation de la température critique dans l’aluminium lors de la diminution de l’épaisseur. J’interprète ce phénomène comme étant lié à un durcissement des phonons, ce qui ne constitue pas une explication habituellement citée.Dans une deuxième partie, on présente des supraconducteurs désordonnés, à savoir l’oxyde d’indium (InOx) et l’aluminium granulaire (GrAl). Dans ces matériaux, on a mis en évidence des excitations sous le gap supraconducteur par des mesures de spectroscopie optique. Ces excitations, dont l’origine est discutée, sont a priori inattendues dans les supraconducteurs conventionnels.Ainsi, on a mis en évidence dans des résonateurs d’oxyde d’indium la détection très sélective en énergie de photons ayant une énergie très inférieure au gap supraconducteur. On explique le mécanisme de détection en démontrant qu’il est lié à l’excitation des modes de résonance d’ordre supérieur, associée à la non linéarité de l’inductance cinétique avec le courant circulant dans le résonateur.Dans l’aluminium granulaire, on a étudié certaines excitations sous le gap supraconducteur dans deux échantillons de résistivité différente. Une antenne radio-fréquences placée devant le cryostat illumine les résonateurs. On choisit un résonateur quelconque et on sélectionne la fréquence des photons délivrés par l'antenne de telle sorte qu'elle corresponde aux différentes excitations que l'on souhaite étudier. On s'intéresse alors à l'influence de la puissance des photons incidents sur l’évolution de la résonance. On met en évidence des comportements non standards de la fréquence de résonance ainsi que du facteur de qualité, selon les excitations étudiéesDuring my PhD-thesis, I studied superconductors thanks to a new optical spectroscopy measurements technique, based on photon detectors for astrophysics. This technique enables measurements ranging from 0 to 300 GHz with a resolution of ~1 GHz at a temperature of ~100 mK. The superconductors are lithographed into resonators whose resonance frequency depends on the superfluid density. During this thesis, I made and studied resonators from different superconducting materials in thin films.Dimensionality plays a fundamental role in superconductors. In principle, in two dimensions a system should not be superconducting but there are a lot of counterexamples like single layer of FeSe or oxide interfaces. In this context, aluminum is particularly interesting for mainly two reasons. First, the superconducting mechanism is conventional : it consists in an electron-phonon coupling. Then, it is pretty easy to modify its thickness (thin films) and its microstructure (granular aluminum).The manuscript is composed of two parts.In the first part, I studied the role played by the thickness on the superconductivity of aluminum thin films, ranging from 15 nm to 200 nm. In most superconductors, the critical temperature decreases with thickness, whereas in some materials like aluminum, it increases. Several theories may explain this phenomenon but there is currently no consensus. Thanks to combined techniques of high resolution optical spectroscopy and of resistivity measurements, I suggest that the origin of the critical temperature increase in aluminum thin films would be phonon hardening. This explanation is not among the popular ones.In the second part, we present disordered superconductors, namely indium oxide (InOx) and granular aluminum (GrAl). In these materials, we evidenced sub-gap optical absorptions. In principle, these absorptions are unexpected in superconductors. We show that they are caused by higher order resonance mode excitations combined with kinetic inductance non-linearity with the current circulating in the resonator.In granular aluminum, we studied some sub-gap excitations in two samples with a different room temperature resistivity. A radio-frequency antenna situated in front of the dilution refrigerator illuminates the resonators. We choose a resonator and we select the photon frequency in such a way that it matches with the different studied excitations. We observe the influence of the incident photon power on the resonance. We evidence non standard behaviors of resonance frequency and quality factor, according to the studied excitations
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Fernandes, Luís Olavo de Toledo. "Tendências espectrais de explosões solares em frequências Sub-THz." Universidade Presbiteriana Mackenzie, 2017. http://tede.mackenzie.br/jspui/handle/tede/3470.
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Fundação de Amparo a Pesquisa do Estado de São Paulo
Fundo Mackenzie de Pesquisa
Previous sub-THz studies were derived from single event observations. Spectral trends for a larger collection of sub-THz bursts have been analyzed for the first time. It consists of a set of 16 moderate to small impulsive solar radio bursts observed at 0.2 and 0.4 THz by the Solar Submillimeter-wave Telescope (SST) between 2012 and 2014 at El Leoncito, in the Argentinean Andes.The peak burst spectra included data from new solar patrol radio telescopes (45 and 90 GHz),and were complemented with microwave data obtained by the RSTN, when available. We evaluate critically errors and uncertainties in sub- THz flux estimates caused by calibration techniques and the corrections for atmospheric transmission, and introduce a new method to obtain uniform flux scale criterion for all 16 events. The sub-THz bursts were searched during reported GOES soft x-ray events of class C or larger, during periods of the SST observations. Seven out of 16 events exhibit spectral maxima in the range 5-40 GHz with fluxes decaying at sub-THz frequencies (3 of them associated to GOES class X, and 4 to class M). Nine out of 16 events exhibited the sub-THz spectral component. From these, 5 events exhibited the sub-THz emission fluxes increasing with frequency separated from the microwave spectral component (2 classified as X and 3 as M) and 4 events have been detected at sub-THz frequencies only (3 classified as M and 1 as C). The results suggest that the THz component might be always present, with the minimum turn-over frequency increasing as a function of the energy of the emitting electrons. In view of the peculiar nature of many sub-THz bursts events, their better understanding requires further investigations of bursts examined on the standpoint of SST observations alone.
Estudos prévios de explosões solares na faixa sub-THz foram derivados de observações de eventos isolados. Tendências espectrais para uma coleção de eventos sub-THz foram analisadas pela primeira vez. O trabalho consiste no estudo e comparação de um conjunto de 16 explosões solares impulsivas muito bem detectadas, classificadas como fracas ou moderadas, observadas em 0,2 e 0,4 THz pelo Telescópio Solar para Ondas Submilimétricas (SST – 𝑆𝑜𝑙𝑎𝑟 𝑆𝑢𝑏𝑚𝑖𝑙𝑙𝑖𝑚𝑒𝑡𝑒𝑟−𝑤𝑎𝑣𝑒 𝑇𝑒𝑙𝑒𝑠𝑐𝑜𝑝𝑒) entre os anos de 2012 e 2014, no parque de 𝐸𝑙 𝐿𝑒𝑜𝑛𝑐𝑖𝑡𝑜, nos Andes Argentinos. Os espectros destas explosões são complementados com dados dos rádio polarímetros (POEMAS - 𝑃𝑂𝑙𝑎𝑟𝑖𝑧𝑎𝑡𝑖𝑜𝑛 𝐸𝑚𝑖𝑠𝑠𝑖𝑜𝑛 𝑜𝑓 𝑀𝑖𝑙𝑙𝑖𝑚𝑒𝑡𝑒𝑟 𝐴𝑐𝑡𝑖𝑣𝑖𝑡𝑦 𝑎𝑡 𝑡ℎ𝑒 𝑆𝑢𝑛) em 45 e 90 GHz, e também com dados em microondas, obtidos pela Rede de Telescópios Solar em Rádio (RSTN – 𝑅𝑎𝑑𝑖𝑜 𝑆𝑜𝑙𝑎𝑟 𝑇𝑒𝑙𝑒𝑠𝑐𝑜𝑝𝑒 𝑁𝑒𝑡𝑤𝑜𝑟𝑘), quando disponíveis. Foram avaliados criticamente os erros e incertezas na estimativa de fluxos na faixa sub-THz, causados pelas técnicas de calibração e correções para transmissão atmosférica, e, assim, introduzido um novo método para obtenção de uma escala de fluxo uniforme, com o mesmo critério para todos os 16 eventos. Os eventos detectados na faixa sub-THz foram analisados e comparados com eventos observados em raios X pelo satélite GOES - 𝐺𝑒𝑜𝑒𝑠𝑡𝑎𝑡𝑖𝑜𝑛𝑎𝑟𝑦 𝑂𝑝𝑒𝑟𝑎𝑡𝑖𝑜𝑛𝑎𝑙 𝐸𝑛𝑣𝑖𝑟𝑜𝑛𝑚𝑒𝑛𝑡𝑎𝑙 𝑆𝑎𝑡𝑒𝑙𝑙𝑖𝑡𝑒, classificados como C, M, ou X, para o mesmo período de operação do SST. A análise estatística é referente a este conjunto de explosões solares muito bem detectadas, onde 7 dos 16 eventos exibiram valores de fluxo máximos na faixa entre 5-40 GHz, com fluxos decaindo nas frequências sub-THz (sendo 3 associados à classe X, e 4 à classe M). Nove dos 16 eventos exibiram a componente espectral sub-THz. Destes, 5 eventos apresentaram emissões na faixa sub- THz com fluxos crescentes com a frequência, separadamente da componente espectral em microondas (2 classificados como X e 3 como M) e 4 eventos foram detectados apenas nas frequências sub-THz (3 com classificação M e 1 com C). Os resultados sugerem que a componente THz pode estar sempre presente, com uma frequência mínima de inversão espectral crescente em função da energia dos elétrons de emissão.
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Kantemur, A., Q. Tang, and H. Xin. "Design of volumetric sub-THz negative refractive index metamaterial with gain." IEEE, 2016. http://hdl.handle.net/10150/622669.
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Conventional passive metamaterials always suffer from the limitation of loss and dispersion due to fundamental causality issue. Especially it becomes severe due to material loss at terahertz frequency. Our work resolves the loss problem by introducing gain device into the metamaterial structure. A passive volumetric metamaterial is firstly designed on the quartz substrate. A negative resistance is inserted into the wire of the structure to provide the gain. We have identified resonant tunneling diodes that work up into THz frequency and shown in simulation that simultaneous negative index and gain can be obtained.
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Moron, Guerra José. "Design of Sub-THz heterodyne receivers in 65 nm CMOS process." Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10053/document.
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Le but de cette thèse est d'explorer les opportunités de design au-delà des fréquences millimétriques en se rapprochant le plus possible de la bande THz en technologie CMOS. L’application spécifique est la détection hétérodyne pour l'imagerie THz. Sachant qu’on vise des fréquences autour de 280 GHz et on travaille avec la technologie CMOS 65 nm, les composant réalisés fonctionnent 80 GHz au-dessus de la fréquence de coupure fmax des transistors utilisés. En termes de réalisation on a développé deux oscillateurs à verrouillage par injection sous-harmonique fonctionnant autour de 280 GHz. La fréquence d’injection de chaque oscillateur est d’environ 47 GHz (1/6 de la fréquence de sortie). Afin de produire des oscillations au-delà de fmax, des techniques de génération harmonique ont été utilisées (push-push, triple-push, etc). Les oscillateurs génèrent des signaux de – 19 et – 14 dBm de puissance à 280 GHz. Chaque composant a été utilisé comme oscillateur local pour des récepteurs hétérodynes fonctionnant à la même fréquence. Ces récepteurs n’ont pas de LNA au début de la chaîne à cause des faibles fréquences de coure néanmoins ils utilisent des mélangeurs passifs afin de pouvoir multiplier des signaux au-delà des limites. Les deux récepteurs développés ont un gain de conversion de – 6 dB et ont des figures de bruit (NF) de 36 et 30 dB. La version la plus performante du récepteur (30 dB de NF) a été intégrée avec une antenne développée par le Labsticc afin de pouvoir réaliser des images Sub-THz avec la détection hétérodyneThe main goal of this thesis is to explore design opportunities beyond the millimeter wave frequencies and to get as close as possible to the THz band using CMOS technologies. The main application is the heterodyne detection for THz imaging. The cut-off frequencies ft/fmax of the used process (65 nm CMOS) are 150/205 GHz, the chosen operation frequency of the developed systems is 280 GHz which means that the circuits developed during this thesis operate at least 80 GHz beyond their fmax cut-off frequency. Two 280 GHz sub-harmonic injection locked oscillators were developed, the injection frequency corresponds to one sixth of the ouput frequency. In order to generate oscillations beyond fmax, harmonic boost techniques are used such as the push-push and triple push techniques. The output power of the oscillators are - 19 and - 14 dBm at 280 GHz. Both components were used as local oscillators for two heterodyne receivers operating around the same frequency. In order to down-covert the Sub-THz signal, a passive resistive mixer is used; this kind of circuit allows mixing beyond the active transistor limits. Also there is no LNA at the begining of the Rx chain since the cut-off frequencies are very low and there will be no gain for amplification at 280 GHz. The conversion gain of both receivers is - 6 dB however the NF's are 36 dB and 30 dB. The best receiver (30 dB) is co-integrated with an antenna (developed by Labsticc) using the same process allowing heterodyne detection THz imaging
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Billet, Maximilien. "Photodétecteurs rapides à la longueur d’onde de 1550 nm pour la génération et la détection d’ondes sub-THz et THz." Thesis, Lille 1, 2018. http://www.theses.fr/2018LIL1I008/document.
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Les photodétecteurs rapides sont des composants optoélectroniques qui permettent de générer et de détecter des ondes de fréquences sub-THz et THz. Cette thèse présente la conception, la fabrication et la caractérisation de photodétecteurs rapides à semiconducteurs III-V. L’objectif est de proposer des systèmes fonctionnant à la longueur d’onde de 1550 nm, et donc compatibles avec les technologies des télécommunications. Nous étudions en détail des photoconducteurs en AsGa-BT pour le sous-échantillonnage, des photodétecteurs de type MSM-InAlAs/InGaAs pour le sous-échantillonnage et le photomélange et des photodiodes UTC en InGaAs/InP pour le photomélangeFast photodetectors are optoelectronic devices wich allow to generate and to detect electromagnetic waves at sub-THz and THz frequencies. This thesis presents the design, the fabrication and the characterization of fast photodetectors made using III-V semiconductors. The objective is to develop systems working at a wavelength of 1550nm, compatibleswith the telecommunication technologies. We will study in detail LT-GaAs photoconductors for sub-sampling, InAlAs/InGaAs-MSM photodetectors for sub-sampling and photomixing and InGaAs/InP UTC-photodiodes for photomixing
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Escate, Maria Victoria Gutierrez. "O estudo das explosões solares simpatéticas e sua observação em frequências SUB-THz." Universidade Presbiteriana Mackenzie, 2015. http://tede.mackenzie.br/jspui/handle/tede/1306.
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Previous issue date: 2015-06-18Fundação de Amparo a Pesquisa do Estado de São Paulo
Sympathetic solar flares are events occurring nearly simultaneously at distinct active regions with physical connection between them. Two flares that occurred on March 8, 2011 in active regions NOAA (National Oceanic and Atmospheric Administration) 11163 (N17W91) and AR 11165 (S20W91) is being studied. The larger flare occurred in the Southern region and was preceded by a smaller flare in the Northern region, about 5 minutes before. Both events were observed by RHESSI. The first explosion was detected by SST in the AR of north hemisphere, in two stages. There are also EUV SDO high cadence images that exhibit a distinct rapid flash coinciding with the SST burst as well as clear large scale magnetic connections between the two active regions. Three possible flare triggering agents from the Northern region towards the Southern region are being investigated: (a) hydrodynamic waves along the large coronal interconnecting magnetic structure, (b) surface Moreton-like shock waves, (c) plasma echoes.
Explosões solares simpatéticas são eventos que ocorrem quase simultaneamente, em regiões ativas distintas. Este trabalho apresenta o estudo de duas explosões solares que ocorreram no dia 8 de março de 2011, nas regiões ativas NOAA 11163 (N17W91) e 11165 (S20W91), entendidas como um evento simpatético característico. A maior explosão ocorreu na região sul, precedida por uma explosão menor na região norte, 5 minutos antes. Ambas detecções foram observadas em raios-X duros pelo satélite RHESSI. A primeira explosão também foi detectada pelo SST na RA do hemisfério norte. Imagens do SDO/AIA em EUV de alta cadência exibem um flash rápido e distinto, coincidente com a detecção do SST. As observações mostram que existem conexões magnéticas em grande escala entre as duas regiões ativas. Isso nos permitiu estudar três possíveis agentes de ativação entre as duas regiões ativas, sendo investigados, então, os seguinte mecanismos de ativação: (i) ondas hidrodinâmicas, ao longo da grande estrutura magnética coronal; (ii) ondas de choque do tipo Moreton, e, (iii) eco de plasma.
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Cortes-Medellin, German, Stefan O'Dougherty, Christopher Walker, Paul F. Goldsmith, Chris Groppi, Steve Smith, and Pietro Bernasconi. "Optical design for the large balloon reflector." SPIE-INT SOC OPTICAL ENGINEERING, 2016. http://hdl.handle.net/10150/622510.
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We present the details of the optical design, corrector system, mechanical layout, tolerances, pointing requirements, and overall performance of the sub-millimeter wavelength Large Balloon Reflector telescope (LBR).
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Graff, David L. "Sub-millimeter Spectroscopy at the Confusion Limit." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1275448827.
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Janke, Christof. "Neuartige Methoden zur Erhöhung der Generationseffizienz kohärenter THz-Strahlung und deren Transmission durch Sub-wellenlängen-Aperturen /." Aachen : Shaker, 2004. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=014182311&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Amado, Rey Ana Belen [Verfasser], Oliver [Akademischer Betreuer] Ambacher, and Roca Yolanda [Akademischer Betreuer] Campos. "Analysis, design, and experimental evaluation of sub-THz power amplifiers based on GaAs metamorphic HEMT technology." Freiburg : Universität, 2018. http://d-nb.info/1160875405/34.
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Pavanello, Fabio. "Uni-travelling carrier photodiodes and metal mesh filters based on sub-wavelength apertures for THz applications." Thesis, Lille 1, 2013. http://www.theses.fr/2013LIL10172/document.
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Le grand intérêt des fréquences THz (0.1-10 THz) pour l’imagerie, la spectroscopie et les communications sans fils a conduit à un important développement de dispositifs pour la génération et la détection d’ondes THz. Les photodiodes à transport unipolaire font partie des principales sources grâce à leur comportement large bande (0-3 THz), leur fonctionnement à température ambiante, leur longueur d’opération à 1.55 µm et leur taille compacte. Le plus grand inconvénient est la leur faible puissance RF générée à haute fréquence (ordre du µW à 1 THz). Une technique pour l’augmenter consiste à utiliser des puissances optiques en entrée plus élevées. Par contre, cette solution peut conduire à leur destruction due à l’échauffement, surtout en cas d’absorption non voulue.Dans la première partie de la thèse un contact électrique basé sur un réseau sub-longueur d’onde a été développé pour réduire ce problème. Cette solution donne des bonnes propriétés électriques, optiques et thermiques avec un procédé plus simple en termes de fabrication et caractérisation par rapport aux travaux précédents.Un deuxième inconvénient est relié à leur caractère non-linéaire qui conduit à un bruit à basse fréquence à cause du large spectre des sources optiques. Ce problème est critique dans le cas de mesures à haute fréquence avec des détecteurs incohérentes car les puissances RF sont très faibles.Dans la deuxième partie de la thèse un filtre passe-haut avec une haute transparence et large bande a été développé sur un diélectrique avec faible pertes aux fréquences THz. Le procédé développé peut être utilisé pour des dispositifs en espace libre grâce aux propriétés optique du diélectriqueThe increasing interest in the THz region (0.1-10 THz) for applications like imaging, spectroscopy and wireless communications is leading to a strong development of devices for the generation and detection of THz waves. Uni-travelling carrier photodiodes (UTC-PDs) are one of the main sources due to their broadband behavior (0-3 THz), room temperature operation, driving wavelength of 1.55 µm and compactness. Their main drawback comes from the low output RF powers at high frequencies (order of µW at 1 THz). A technique to increase their RF powers consists in using higher optical driving powers. However, this solution may lead to their failure because of heating, especially in case of unwanted absorption.In the first part of the thesis an electrical contact based on sub-wavelength apertures has been developed to reduce this issue. This solution has been shown valuable under multiple aspects. It provides good electrical, optical and thermal properties, while leading to an easier process in terms of fabrication and characterization with respect to previous works.A second drawback of UTC-PDs is due to their non-linear behavior which leads to a noise at low frequency because of the broad spectrum of the driving optical signals. This issue is critical for measurements at high frequencies with incoherent detectors due to the low RF powers to be detected.In the second part of the thesis a high-transparency broadband high-pass mesh filter has been developed on a novel low-loss dielectric material to filter-out this noise. The developed process can be exploited in other free-space devices like metamaterials due to the remarkable properties of this dielectric at THz frequencies
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Jung, Cécile. "Conception et fabrication de circuits intégrés basés sur les nano-diodes Schottky GaAs fonctionnant aux fréquences THz et sub-THz pour les récepteurs hétérodynes spatiaux dédiés à l'astrophysique." Paris 11, 2009. http://www.theses.fr/2009PA112240.
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L'objectif de ce travail de thèse est de concevoir et réaliser des circuits mélangeurs à 330GHz et à 183GHz pour la détection hétérodyne en astrophysique. Ces circuits sont basés sur les diodes Schottky, permettant ainsi un fonctionnement à température ambiante. Le thème principal de la thèse consiste à élaborer un protocole de fabrication de diodes Schottky submicroniques et à les intégrer dans des circuits mélangeurs. Ces circuits seront assemblés dans un bloc de test et caractérisés en termes de performances RF. Ce travail de thèse pourra être utilisé pour des circuits à plus hautes fréquences, aussi bien pour les mélangeurs que pour les multiplicateurs. Un processus de fabrication entièrement basé sur la lithographie électronique a été développé, permettant la réalisation de diodes Schottky ayant des anodes submicroniques et le perfectionnement de leurs caractéristiques électriques. De nombreuses études spécifiques d'optimisation de contact ohmique et de contact Schottky ont permis d'obtenir des résistances en séries inférieures à 10Ω et des meilleurs facteurs d'idéalité entre 1,08 et 1,15. Deux types de circuits ont été réalisés. L'un pour un fonctionnement à 330GHz composé d'une paire d'anodes anti-parallèles sur une membrane de 10μm. L'autre, pour une fréquence de fonctionnement à 183GHz, consiste en un circuit MMIC comprenant une paire d'anodes anti-parallèles sur une membrane de 50μm. Un des composants à 330GHz a été intégré dans un bloc mélangeur et ses performances RF ont été caractérisées. Le résultat préliminaire a été encourageant avec une température de bruit de 1800K pour une perte en conversion de 8dBThe objective of this thesis is to design and integrate circuits mixers at 330GHz and 183GHz for heterodyne detection in astrophysics. These circuits are based on Schottky diodes, allowing operation at room temperature. The main point of the thesis is to develop a protocol for fabrication of submicron Schottky diodes and to integrate them in circuits mixers. These circuits are integrated in a test block and characterized in terms of RF performances. This thesis work may be used for circuits at higher frequencies, for both mixers and multipliers. A fabrication process entirely based on electron beam lithography has been developed, allowing the realization of Schottky diodes with submicronic anodes and improvement of their electrical characteristics. Many studies for specific optimization of the ohmic and schottky contacts have yielded to series resistances below 10Ω and to best ideality factors between 1,08 and 1,15. Two types of circuits have been made. One for operation at 330GHz composed of a pair of anti-parallel anodes on a 10μm membrane. The other, for a frequency of 183GHz, consists of a MMIC circuit including a pair of anti-parallel anodes on a 50μm membrane. One of the components to 330GHz has been integrated into a mixer bloc, its RF performances have been characterized. The preliminary result was encouraging with a noise temperature of 1800K for a conversion loss of 8dB
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Janke, Christof [Verfasser]. "Neuartige Methoden zur Erhöhung der Generationseffizienz kohärenter THz-Strahlung und deren Transmission durch sub-wellenlängen Aperturen / Christof Janke." Aachen : Shaker, 2004. http://d-nb.info/1181620864/34.
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Kaltenecker, Korbinian J. [Verfasser], Hanspeter [Akademischer Betreuer] Helm, Markus [Akademischer Betreuer] Walther, and Bernd-Michael [Akademischer Betreuer] Fischer. "Breaking the diffraction limit : experiment and theory on sub-diffraction limited focusing and imaging realised in the THz frequency regime." Freiburg : Universität, 2016. http://d-nb.info/1119899370/34.
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Gidel, Vincent. "Contribution à la modélisation RF de diode Schottky intégrée en Technologie BiCMOS 55 nm et visant des applications sub-THz." Thesis, Université Côte d'Azur, 2020. http://www.theses.fr/2020COAZ4088.
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Dans un monde qui doit faire face aux défis de la mobilité et de la sécurité, le besoin croissant d’applications adaptées aux nouveaux modes de vie a fait émerger de nouveaux marchés technologiques. L’enjeu réside à la fois dans l’augmentation du trafic mondial de données mobiles ainsi que dans la conception de systèmes de détection LiDAR plus efficients. Cette tendance duale a motivé de nombreux travaux de recherche en bande millimétrique afin de développer de circuits toujours plus performants. Les recherches scientifiques présentées dans cette thèse s’inscrivent dans ce sens. La première partie de l’étude porte sur le développement d’une architecture de diode Schottky innovante en technologie BiCMOS 55. Les diodes conçues montrent des performances intrinsèques à l’état de l’art avec des fréquences de coupure avoisinant les 1 THz. Une stratégie de modélisation analytique a été initiée en s’appuyant sur le dimensionnel et la physique de l’architecture et se montre efficacement en bon accord avec les facteurs de mérite extraits des mesures. Les diodes sont ensuite incluses dans deux circuits démonstrateurs. Le premier est un mélangeur sous-harmonique intégré sur silicium fonctionnant autour de 106 GHz. La conception du mélangeur s’appuie sur l’utilisation conjointe de l’architecture de diode Schottky et du modèle analytique développés en technologie BiCMOS 55nm. Malgré des pertes de conversion de 20,3 dB, la réception d’un signal QAM-16 démodulé avec un débit de 40 Gbit/s a pu être démontrée. Le second circuit démonstrateur porte sur le développement d’un pixel unitaire pour des applications d’imagerie fonctionnant à 2,5 THz. Cette deuxième étude propose également une stratégie détaillée de conception d’antennes intégrées en technologie silicium. L’objectif est d’établir la faisabilité de ces circuits innovants sur des technologies silicium commerciales en vue de s’insérer dans les marchés 5G et LiDAR afin d’adresser les enjeux actuelsIn a world facing new challenges such as mobility or safety, the increasing demand of applications fitted to new ways of life has driven the emergence of new technology markets. The challenge twofold lies in the rise of global mobile data traffic and the design of more efficient LiDAR sensor’s systems. This dual trend has prompted research studies on millimeter-wave bands in order to contribute to the development of increasingly competitive electronics circuits. Scientific researches presented in this thesis falls within this perspective. The first part of the study deals with the development of an innovative Schottky diode architecture in BiCMOS 55 nm technology. The fabricated Schottky diodes show state-of-the-art intrinsic performance with cut-off frequencies nearby 1 THz. An analytical modeling strategy have been initiated by leveraging the architecture dimensions and physics to efficiently provide à fair agreement with the factor of merit extracted from measurements. Some of these devices are then included in two demonstrator circuits. The first one is a silicon-based subharmonic mixer operating around 106 GHz. The subharmonic mixer design relies on the collaborative use of the Schottky diode architecture and the analytical lumped model developed in BiCMOS 55nm technology. Despite a 20.3 dB conversion loss, the reception of QAM-16 demodulated signal with data rate up to 40 Gbit/s has been achieved. The second circuit concerns a unit pixel for imager applications operating at 2.5 THz. This second study also suggests a detailed strategy of the integrated antennas designed in silicon technology. This research work aims at determining the feasibility innovative circuits designed with commercially available silicon technologies in order to address 5G and LiDAR markets
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Seif, Marcelino. "Caractérisation et modélisation des sources de bruit BF dans les transistors bipolaires développés en technologie BiCMOS (sub 0,13µm) pour applications RF et THz." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS127/document.
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Les travaux de thèse, présentés dans ce manuscrit, portent sur la caractérisation et la modélisation des sources de bruit basse fréquence dans les transistors bipolaires à hétérojonction Si/SiGe:C issus des filières BiCMOS 130 et 55 nm utilisées pour la réalisation de circuits intégrés dédiés aux futures applications dans le domaine du THz. A partir des mesures réalisées en fonction de la polarisation, de paramètres géométriques (surface et périmètre d'émetteur principalement) et de la température, la composante de bruit en 1/f, associée aux fluctuations du courant de base, a été entièrement caractérisée et les sources de bruit associées localisées. Les paramètres du modèle compact SPICE ont été extraits et comparés avec ceux de la littérature. Pour la technologie BiCMOS 130 nm, la valeur obtenue pour la figure de mérite KB égale 6,8 10-11 µm² ce qui représente le meilleur résultat publié à ce jour, toutes filières de transistors bipolaires confondues. Réalisée sur une plaque entière, l'étude statistique de la dispersion du niveau de bruit en 1/f a permis d'étendre la modélisation compacte de type SPICE. Mesuré sur une large gamme de température, le niveau de bruit en 1/f n'a pas présenté de variation significative. Pour la première fois, une étude complète de la composante de bruit en 1/f associée aux fluctuations du courant de collecteur est présentée et les paramètres du modèle SPICE extraits. Concernant la caractérisation des composantes de génération-recombinaison (présence non systématique), une étude statistique a montré que les transistors de plus petites dimensions étaient les plus impactés. La comparaison entre les différentes technologies montre que ces composantes sont beaucoup plus présentes dans les technologies les moins matures. Quand ces composantes ont été associées à du bruit RTS, une méthode de caractérisation temporelle et fréquentielle a été mise en œuvre. Enfin, dans certains cas, une étude en basses températures a permis d'extraire les énergies d'activation des pièges responsables de ces composantes de génération-recombinaisonThe presented thesis work, in this manuscript, focuses on the characterization and modeling of the low frequency noise sources in heterojunction bipolar transistors Si/SiGe :C derived from 130 to 55 nm BiCMOS technology used in the production of integrated circuits dedicated for THz domain applications. From measurements versus bias, geometrical parameters (emitter area and perimeter) and temperature, the 1/f noise component, associated to the base current fluctuations, has been fully characterized and the associated sources have been localized. The SPICE compact model parameters have been extracted and compared with those of the literature. For the BiCMOS 130 nm technology, the obtained figure of merit value of 6,8 10-11 µm2 represents the best published result so far in all bipolar transistors. The dispersion study of the 1/f noise component, performed over a complete wafer, allowed us to extend the SPICE type compact modeling. Measured over a large temperature range, the 1/f noise did not show any variations. For the first time, a complete characterization of the 1/f component at the output of the transistors is presented as well as the extraction of SPICE parameters. Regarding the characterization of generation-recombination components (unsystematic presence), a statistical study has showed that transistors with small emitter areas (Ae < 1 µm2) are affected more than the transistors with large emitter areas by the presence of g-r components. Comparison between different technologies shows that these components are much more present in the less mature technologies. When these components have been associated to RTS, time and frequency domain method is implemented. Finally, in some cases, a study at low temperatures was used to extract the activation energy of the traps responsible for the generation-recombination components
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Mirando, Dinesh Amal. "Millimeter – Wave/Terahertz Chirped Michelson Interferometer Techniques for Sub Surface Sensing." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1484698597373738.
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Cetnar, John S. "Atmospheric Effects on the Propagation of MMW and Sub-MMW Radiation." Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1276703479.
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Pítra, Kamil. "Antény pro oblasti (sub)milimetrových vln." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-233662.
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Disertační práce se zabývá návrhem a optimalizací kruhově polarizované anténa pro oblast terahertzových kmitočtů. V práci se věnuji zjednodušené teorii terahertzového zdroje a návrhu vhodné antény pro tento zdroj. Návrh je zaměřen na dosažení kruhové polarizace z lineárně polarizovaných antén. Abych potlačil šíření povrchové vlny na elektricky tlustém dielektrickém substrátu, věnuji se návrhu a optimalizaci specifických periodických struktur. Návrh těchto struktur je poměrně komplikovaný, protože neexistuje přímočarý vztah mezi vlastnostmi struktur s elektromagnetickým zádržným pásmem (EBG) a geometrií buňky. Abych vhodně koncentroval vyzařovanou energii do úzkého svazku, věnuji se návrhu a optimalizaci částečně odrazného plochy (PRS), které působí jako planární čočka pro terahertzovou anténu.
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Nader, Esfahani Nima. "Terahertz and Sub-Terahertz Tunable Resonant Detectors Based on Excitation of Two Dimensional Plasmons in InGaAs/InP HEMTs." Doctoral diss., University of Central Florida, 2014. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6327.
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Plasmons can be generated in the two dimensional electron gas (2DEG) of grating-gated high electron mobility transistors (HEMTs). The grating-gate serves dual purposes, namely to provide the required wavevector to compensate for the momentum mismatch between the free-space radiation and 2D-plasmons, and to tune the 2DEG sheet charge density. Since the plasmon frequency at a given wavevector depends on the sheet charge density, a gate bias can shift the plasmon resonance. In some cases, plasmon generation results in a resonant change in channel conductance which allows a properly designed grating-gated HEMT to be used as a voltage-tunable resonant detector or filter. Such devices may find applications as chip-scale tunable detectors in airborne multispectral detection and target tracking.
Reported here are investigations of InGaAs/InP-based HEMT devices for potential tunable resonant sub-THz and THz detectors. The HEMTs were fabricated from a commercial double-quantum well HEMT wafer by depositing source, drain, and semi-transparent gate contacts using standard photolithography processes. Devices were fabricated with metalized transmission gratings with multiple periods and duty cycles. For sub-THz devices, grating period and duty cycle were chosen to be 9 ?m and 22%, respectively; while they were chosen to be 0.5 ?m and 80% for the THz device. The gratings were fabricated on top of the gate region with dimensions of 250 ?m x 195 ?m.
The resonant photoresponse of the larger grating-period HEMT was investigated in the sub-THz frequency range of around 100 GHz. The free space radiation was generated by an ultra-stable Backward Wave Oscillator (BWO) and utilized in either frequency modulation (FM), or amplitude modulation (AM) experiments. The photoresponse was measured at 4K sample temperature as the voltage drop across a load resistor connected to the drain while constant source-drain voltages of different values, VSD, were applied. The dependence of such optoelectrical effect to polarization of the incident light, and applied VSD is studied. The results of AM and FM measurements are compared and found to be in agreement with the calculations of the 2D-plasmon absorption theory, however, a nonlinear behavior is observed in the amplitude and the line-shape of the photoresponse for AM experiments. For detection application, the minimum noise-equivalent-power (NEP) of the detector was determined to be 235 and 113 pW/Hz1/2 for FM and AM experiments, respectively. The maximum responsivity of the detector was also estimated to be ~ 200 V/W for the two experiments.
The far-IR transmission spectra of the device with nanometer scale period was measured at 4 K sample temperature for different applied gate voltages to investigate the excitation of 2D-plasmon modes. Such plasmon resonances were observed, but their gate bias dependence agreed poorly with expectations.Ph.D.
Doctorate
Physics
Sciences
Physics
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Cabbia, Marco. "(Sub)-millimeter wave on-wafer calibration and device characterization." Thesis, Bordeaux, 2021. http://www.theses.fr/2021BORD0017.
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Les mesures de précision jouent un rôle crucial dans l'électronique, en particulier dans la caractérisation des transistors bipolaires à hétérojonction (HBT) à base de silicium embarqués dans des dispositifs pour applications THz utilisant la technologie BiCMOS. Grâce aux innovations récentes en termes de fabrication de technologies à l'échelle nanométrique, les dispositifs capables de fonctionner dans la région des ondes submillimétriques deviennent une réalité et doivent répondre à la demande de circuits et de systèmes haute-fréquence. Pour disposer de modèles précis à de telles fréquences, il n'est plus possible de limiter l'extraction des paramètres en dessous de 110 GHz, et de nouvelles techniques permettant d'obtenir des mesures fiables de dispositifs passifs et actifs doivent être étudiées.Dans cette thèse, nous examinerons la caractérisation des paramètres S sur silicium (on-wafer) de différentes structures de test passives et des HBT SiGe en technologie B55 de STMicroelectronics, jusqu'à 500 GHz. Nous commencerons par une introduction de l'équipement de mesure habituellement utilisé pour ce type d'analyse, puis nous passerons aux différents bancs de mesure adoptés au laboratoire IMS, et enfin nous nous concentrerons sur les techniques de calibrage et d’épluchage (de-embedding), en passant en revue les principales criticités de la caractérisation haute-fréquence et en comparant deux algorithmes de calibrage on-wafer (SOLT et TRL) jusqu'à la bande WR-2.2.Deux cycles de production de photomasques pour la caractérisation on-wafer, tous deux conçus à l'IMS, seront présentés: nous introduirons un nouveau design du floorplan et évaluerons sa capacité à limiter les effets parasites ainsi que l'effet de son environnement (substrat, structures voisines et diaphonie). Pour notre analyse, nous nous appuierons sur des simulations électromagnétiques et des simulations EM mixtes de modèle compacte + sonde, toutes deux incluant les modèles des sonde pour une évaluation des résultats de mesure plus proche des conditions réelles.Enfin, nous présenterons quelques structures de test pour évaluer les impacts indésirables sur les mesures d'ondes millimétriques et de nouvelles solutions de conception de lignes de transmission. Deux designs prometteurs seront soigneusement étudiées: le "layout M3", qui vise à caractériser le DUT dans un étalonnage à un seul niveau, et les "lignes à méandre", qui maintiennent la distance entre les deux sondes constante en évitant tout déplacement pendant les mesures sur siliciumPrecision measurements play a crucial role in electronic engineering, particularly in the characterization of silicon-based heterojunction bipolar transistors (HBTs) embedded into devices for THz applications using the BiCMOS technology. Thanks to ongoing innovations in terms of nanoscale technology manufacturing, devices capable of operating in the sub-millimeter wave region are becoming a reality, and need to support the demand for high frequency circuits and systems. To have accurate models at such frequencies, it is no longer possible to limit the parameter extraction below 110 GHz, and new techniques for obtaining reliable measurements of passive and active devices must be investigated.In this thesis, we examine the on-wafer S-parameters characterization of various passive test structures and SiGe HBTs in STMicroelectronics' B55 technology, up to 500 GHz. We start with an introduction of the measuring equipment usually employed for this type of analysis, then moving on to the various probe stations adopted at the IMS Laboratory, and finally focusing on calibration and deembedding techniques, reviewing the major criticalities of high-frequency characterization and comparing two on-wafer calibration algorithms (SOLT and TRL) up to the WR-2.2 band.Two photomask production runs for on-wafer characterization, both designed at IMS, are considered: we introduce a new floorplan design and evaluate its ability to limit parasitic effects as well as the effect of the environment (substrate, neighbors, and crosstalk). For our analysis, we rely on electromagnetic simulations and joint device model + probe EM simulations, both including probe models for an evaluation of measurement results closer to real-world conditions.Finally, we present some test structures to evaluate unwanted impacts on millimeter wave measurements and novel transmission line design solutions. Two promising designs are carefully studied: the "M3 layout", which aims to characterize the DUT in a single-tier calibration, and the "meander lines", which keeps the inter-probe distance constant by avoiding any sort of probe displacement during on-wafer measurements
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Gacemi, Djamal Eddine. "Étude expérimentale et simulation des modes électromagnétiques se propageant sur des guides d’ondes métalliques de petites dimensions aux fréquences THz." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112413.
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Focaliser l’énergie optique en un petit spot de diamètre beaucoup plus petit que la limite de diffraction a longtemps été un sujet très intéressant en photonique. Dans le domaine Térahertz (avec une longueur d’onde de l’ordre de 300 µm) ce défi est particulièrement important pour répondre à l’intérêt croissant de l’imagerie haute résolution et de la spectroscopie des matériaux d’une taille inférieure à l’échelle submillimétrique de la longueur d’onde en espace libre. Dans ma thèse, j’ai étudié le confinement des ondes de surface aux fréquences THz sur des structures métalliques de dimensions sous longueur d’onde. J’ai expérimentalement mesuré le confinement du champ électrique et calculé la relation de dispersion du mode de surface sur une structure métallique déposée sur un substrat diélectrique de faible permittivité. Ces mesures sont obtenues à l’aide d’un banc de mesures THz guidé, développé pendant ma thèse. La mesure est faite en champ proche par une sonde électro-optique micrométrique, librement positionnable. Ces résultats expérimentaux sont complétés par des simulations numériques, obtenues par le logiciel de simulation par éléments finis, Comsol Multiphysics. Les résultats expérimentaux montrent un confinement de λ/20 du mode EM de surface sur une ligne métallique rectangulaire de petites dimensionsFocusing optical energy into a small spot diameter much smaller than the diffraction limit has long been a very interesting topic in photonics. In Terahertz (with a wavelength of about 300 microns) this challenge is particularly important to meet the growing interest in high-resolution imaging and spectroscopy of materials whose size is smaller than the wavelength in free space. In my thesis, I studied the confinement of surface waves at THz frequencies on metal structures with sub-wavelength dimensions . I experimentally measured the confinement of the electric field and calculated the dispersion relation of the surface mode on a metal structure deposited on a low permittivity dielectric substrate. These measurements are obtained using a guided-wave time domain spectroscopy set-up, developed during my PhD. The measurement is made by a near-field freely positionable electro-optical probe. These experimental results are supplemented by numerical simulations obtained by finite element analysis software Comsol Multiphysics. The experimental results show a confinement of λ/20 of the EM surface mode on a sub-wavelength dimension rectangular metal wire
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Li-jhen-li and 李麗珍. "A study of sub-THz gyrotron drives." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/86367430376090427810.
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碩士南臺科技大學
光電工程系
105
The gyrotron backward-wave oscillator is a high-power oscillator that converts the energy of the electron beam into millimeter-wave by the frequency of the electron cyclotron and has a broadband regulation and a low operating voltage characteristic. However, due to its required external magnetic field is too high and the efficiency is too low, so that its practicality reduced. Therefore, this study discusses the large cyclotron radius of the gyrotron backward-wave oscillator, the use of high-order harmonic mechanism to reduce the required external magnetic field, and improve its output power. In addition to the characteristics and development of the gyrotron backward-wave oscillator, this paper includes the history of gyrotron development, nonlinear theory and boundary condition setting, program simulation and operation flow, mode selective circuits. And the oscillation characteristics of different harmonics are analyzed, including the relationship between the start-oscillation current and the applied magnetic field, and the influence of the output power and frequency on the applied magnetic field. We use the steady-state nonlinear program to analyze the results. It is found that the start-oscillation current of the TE_3,7^((3) ) mode with uniform structure is obviously increased with the decrease of the magnetic field, and the operating current is also increased,TE_2,5^((2) )、TE_5,11^((5) ) competition modes occur. Therefore, we use the non-uniform structure of the gyrotron backward-wave oscillator, but TE_3,7,2^((3) ) in the magnetic field range 103.7 ~ 105kG with the lowest start- oscillation current of 0.2 ~ 0.6A, may be with TE_3,7,1^((3) ) produces an axial competition pattern. Finally, we found TE_3,7,3^((3) ) mode, yields output power and frequency on the external magnetic field relationship, found that in TE_3,7,3^((3) ).The simulation results show that the maximum stable output power of TE_3,7,3^((3) ) gyrotron backward-wave oscillator is 4.0 ~ 5.5kW when the magnetic field is 103kG current is 0.6A. In order to make the TE_3,7,3^((3) )mode have low start- oscillation current and high oscillation power, the oscillator radius (Δr)、 magnetic field (ΔB) will be adjusted to increasee the inlet end radius, The simulation results show that the increase of the radius ∆r_w = 1.5×〖10〗^(-4)cm, the oscillation power of 4.0 ~ 5.6kW, adjustable frequency up to 0.4GHz; increase the ΔB =1.1 kG, the oscillation power up to 4.0~5.6 kW, adjustable frequency Up to 0.4GHz .
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Huang, Cheng-yu, and 黃丞宇. "Sub-THz Photonic-Transmitters by 850nm Wavelengths Optical Pulse Pumping." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/pe9n29.
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碩士國立中央大學
電機工程研究所
96
In this paper, we demonstrated two novel photonic transmitters; one is composed of low-temperature-grown GaAs (LTG-GaAs) based separated-transport-recombination photodiode (STR-PD) and the other is GaAs/AlGaAs based Uni-traveling-carrier photodiode (UTC-PD). Both devices are integrated with broadband micromachined monopole antennas but without the integration with Si-lens. Under femto-second optical pulse illumination which the wavelength of around 800nm, the photonic-transmitter can radiate strong sub-THz pulses (20mW peak-power) with a wide bandwidth (100~250GHz). Such result was directly measured by a THz-TDS system, which could be used as a THz UWB data link system. The bias dependent high-peak-power performance of our device implies its application of photonic emitter and data modulator in photonic sub-THz UWB system.
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高文哲. "A study of sub-THz gyrotron devices with external injection signals." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/48473400496788347372.
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碩士南臺科技大學
光電工程系
105
The gyrotron traveling-wave amplifiers(gyro-TWAs) is a high power,broadband,millimeter-wave amplifier,applied in communication,military radarNMR(nuclear magnetic resonance). This study presents a comparative three schemes analysis of fourth-harmonic multiplying gyro-TWA, M=1, M=2 and M=4, respectively. Absolute instabilities in the gyro-TWA are suppressed by distributed-wall losses and a mode selective circuit. The amplification of the waves in a gyro-TWA depends on the lengths of the sections, and the simulated results show that the gain increases for all schemes, as the length of the lossy section or the length of the copper section increases. Finally, at a different multiplier ratio (M = 1, M = 2, M = 4) there is almost the same saturated output powers 15kW and saturated gain 48dB. The fourth chapter is the 900 GHz injection signals drives gyrotron, in order to suppress the mode to avoid competition with the mode,first to use the injection TE89 mode backward power to drive the oscillator to form a phase-locked; and to change the power from the forward injection mode , To the cluster the electron beam amplification mode of operation, suppress the mode, but the results show no matter how much power is injected. Therefore, it is shown that there are two kinds of steady-state solutions, which can not completely suppress the competition mode of the fundamental harmonics, by the backward of and forward wave to the oscillator. In order to avoid the competition of the oscillator mode, this study will reduce the applied magnetic field B0, change the length L5, input segment L1, isolation length L3 and current Ib. From these results, the optimal operating parameters are L1=1.09cm，L2=0.3cm，L3=0.4cm，L4=0.3cm，L5=1.1cm，B0=166.8kG，Vb=30kV，Ib=3A，α=1.1， =5%。Based on the relationship between the output power of the Gyro-TWT and the input power , the results show that the linear gain is about 45dB between Pin = 10-4 ~ 0.05W and Pin = 0.1W saturation gain of 50dB. In addition, the Gyro-TWT saturation power Psat and frequency f relationship shown, the operating frequency of 888.7GHz, maximum power of 6.2kW, bandwidth is about 0.6GHz,gain of 47dB.
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Li, Yu-Tai, and 黎宇泰. "A Study of Sub-THz Impulse Radio Photonic Devices and Application." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/41695931545175167661.
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博士國立交通大學
光電工程系所
97
This study investigates of the key components of optical electrical devices operating in the THz and Sub-THz range (0.1~1THz), including photoconductive (PC) antennas and photonic transmitters (PTs). PTs are integrated high speed photo diodes with printed planar antennas designed based on the required radiation frequency range. This study also examines related high frequency measurement systems and broadband communication applications. The feasibility of several novel photonic transmitters is demonstrated first, which are designed for high peak power generation and wireless ultra-wideband (UWB) communication. Initially, the feasibility of a PT composed of a low-temperature-grown GaAs (LTG-GaAs) based separated-transport-recombination photodiode (STR-PD) and a micromachined slots antenna is demonstrated. Under femto-second (fs) optical pulse illumination, this device radiates strong electrical pulses (300 mW peak power) at a designed frequency of 500GHz. A traditional LTG-GaAs based PT under high, externally applied electrical fields (>50kV/cm) is then eliminated using our STR-PD based PTs (STR-PTs). Monolithic integration of a GaAs/AlGaAs based uni-traveling-carrier photodiode (UTC-PD) with a broadband micromachined antenna creates UTC-PD based PTs (UTC-PTs) that can also radiate strong sub-THz pulses (20mW peak-power) with a narrow pulse-width (<2ps) and wide bandwidth (100~250GHz). The bias dependent peak output-power of both PTs (UTC- and STR-PD based) makes them highly promising for use as a data modulator/emitter for a photonic UWB system. This study also describes in detail the characterization of two high power PTs based on two high power photodiodes, UTC-PD and STR-PD. Both PDs have the same depletion layer thickness, i.e. the same theoretical RC-limited bandwidth, and are monolithically integrated with the same broadband micro-machined circular disk monopole antennas. However, the STR-PD based transmitter exhibits a significantly different dynamic and static performance from that of the UTC-PD based transmitter due to a low temperature grown GaAs (LTG-GaAs) based recombination center inside the active region, as well as a much thinner thickness of an effective depletion layer. Under optical pulse excitation (~480pJ/pulse), the STR-PD based transmitter exhibits a markedly lower maximum average output photocurrent (1.2mA vs. 0.3mA) than that of the UTC-PD transmitter. This is despite the fact that the radiated electrical pulse width and maximum peak power, which are determined by the same THz time domain spectroscopic (TDS) system, of both devices are comparable. Next, high power THz generation by using PC antennas is studied by comparing the emission properties of LT-GaAs PC antennas with GaAs:O PC antennas in the pulse and CW mode. GaAs:O PC antennas can generate a higher THz power than LT-GaAs based both in the pulsed and CW modes. The bandwidths of GaAs:O PC antennas and LT-GaAs PC antennas are measured at approximately 1THz both under pulse (TDS) and CW (photomixing) pumping. However, the THz power of LT-GaAs PC antenna becomes saturated in CW mode, while GaAs:O does not. This finding suggests that GaAs:O PC antenna is a more reliable THz emitter than LT-GaAs, which is difficult to reproduce. To excite THz and Sub-THz radiation, not only are a Ti:Sappire laser (��=800nm) and fiber mode locked laser (��=1550nm) used, but a CW excitation system is also established, which consists of two laser diodes (��=800nm) . The radiated powers of all devices are compared using a Helium-cooled bolometer. Additionally, radiated electrical fields are measured by a TDS system, which is based on LTG-PC antennas. The power spectrum of devices can be determined following fast Fourier transformation (FFT). A wideband communication system is also adopted by using a high speed horn (W band, 75~110GHz) antenna as a receiver to demonstrate the effectiveness of sub-THz wideband communication, which displays an improved data transmission rate. Finally, this study demonstrates the feasibility of wideband communication applications by using our sub-THz emitters as follows: (1) Communication quality of the LTG-GaAs PC antennas based TDS system is improved by using Manchester coding; and (2) A wideband carrier (W band, 75~110GHz) is generated by using a fiber mode-locked laser as system optical source and determining its maximum data transmission rate. In (1), the Ti: Sapphire laser is adopted as the excitation source and we demonstrate that the bit error rate (BER) improved from 10-8 to10-12 by using Manchester coding. In (2), data transmission of 2.5Gbit/s at W band is successfully demonstrated by utilizing the advantage of a high repetition rate of fiber mode-locked laser.
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Chiu, Chih-Heng, and 邱治恒. "High power and high efficiency Sub-THz Photonic-Transmitters at 850nm wavelength." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/41673244531960954322.
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碩士國立中央大學
電機工程研究所
95
We demonstrate a novel photonic transmitter, which is composed of a low-temperature-grown GaAs (LTG-GaAs) based separated-transportrecombination photodiode (STR-PD) and a micromachined slot antenna. Under femto-second optical pulse illumination and Continuous-Wave(CW) illumination, this device radiates strong electrical pulses (4.5mW peak power) without the use of a Si-lens. It can be observed in the Fourier Transform Infrared Spectrometer (FTIR) spectrum of radiated pulses that a significant resonance, with a peak power of approximately 300W peak power, occurs at 500GHz, which corresponds to the designed resonant frequency of the slot antenna. The saturation problem related to the output THz power that occurs with the traditional LTG-GaAs based photonic-transmitters when operated under high external applied electrical fields (>50kV/cm) has been eliminated by the use of our device.
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Wang, Yan-Ting, and 王艶婷. "DESIGN OF SUB-THZ RECEIVER-BASED PHASE-LOCKED LOOP IN CMOS TECHNOLOGY." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/50029222313352172612.
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碩士國立交通大學
電子研究所
101
In contrast to X-ray, THz wave (300GHz-3THz,T-ray) is a non-ionized light source for non-invasive detection of biological tissues without the concern of much radiation exposure. Thus it is believed as an emerging technology for next generation medical imaging system. Additionally, T-ray is capable to penetrate clothing and many (non-metallic) packaging materials. It opens up unique screening possibilities for detection of concealed weapons, chemicals and biological agents, tumors, cavities, and also opportunities for short range radars and secured high data rate wireless communications. Until recently, THz range signal sources are mostly addressed by silicon-germanium process or bulky and expensive optics. As the fmax of CMOS reach over 200GHz, it opens up an opportunity to provide a small size and low cost platform in CMOS technology. In this paper, we proposed a CMOS technique to realize a sub-THz signal source, which can be further boosted into THz range with the aid of phase combination or push-push techniques to open up opportunities of THz applications. To implement a high speed PLL, several cascaded injection-locked frequency divider are used to down convert the high speed output frequency for phase comparison in conventional architecture. For the oscillation frequency close to hundreds of GHz range, the frequency tuning ranges of both VCO and ILFD become very limited, which are highly susceptible to parasitic effects associated with the buffer stage and interconnects. As the injection-locked frequency divider is tend to self-oscillation if it isn’t injection locked properly, the frequency misalignment in divider chain are susceptible to PVT variation and may narrow the locking range of the PLL or cause the loop fail to lock. To circumvent this critical issue, we propose a novel receiver-based PLL (RX-PLL) for over 100GHz operations. In the proposed RX-PLL, the high speed prescalers are replaced by a harmonic mixer. And with the aid of RSSI for automatically frequency sweeping, the phase-locked loop is capable of fast locking and free of misalignment problems. In this thesis, the background of THz signal source will be introduced, and several architectures for high speed PLL will be discussed. Then we proposed a receiver-based architecture and discuss its behavior and noise model. After that, we accomplished a 160GHz RX-PLL and take it as an example to introduce the detail schematics, and then demonstrate its measurement results. Finally, I will summarize the main results of this thesis. The recommendations for future works are also addressed.
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Hsu, Meng-Tse, and 徐孟澤. "A Micromaching Sub-THz Reflector Antenna for Gain Enhancement and Near Field Focus Application." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/7su4k2.
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碩士國立交通大學
電子研究所
106
This paper will present the first silicon-based parabolic Sub-THz reflector antenna with corresponding fabrication processes. The antenna is side fed with an on-chip 340 GHz patch antenna on a reflector made of stacked micromachined silicon substrates with a parabolic-shaped Kapton film coated with aluminum on top. The antenna with a size of 18 x18 x4 mm3 and an aperture of ~10mm can be easily integrated with MMIC (Monolithic Microwave Integrated Circuit) sources, i.e. 40 nm CMOS triple-push oscillator in this case, and exhibit not only ~12.4 dB directive gain enhancement and 4.34° HPBW (Half Power BeamWidth) for far field radiation but also an excellent near field focus characteristic with a 28.5 mm depth of field (DOF). In comparison with the prior arts listed, the characteristics of small form factor, high gain enhancement and minimal HPBW has shown the potential of the reflector antenna for high-speed data transmission and THz imaging system applications.
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Zeng, Yu-lon, and 曾郁崙. "High-Performance GaAs0.5Sb0.5/InP UTC-PD with Graded-Bandgap Collector for Zero-Bias Operation at Sub-THz Regime." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/23749597390333158527.
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碩士國立中央大學
電機工程學系
104
High-speed and high-power photodiodes (PDs) serve as the key component in the millimeter-wave-over-fiber (MoF) or THz wireless communication system. In order to boost the speed of PD up to THz regime, downscaling the depletion layer thickness and device active area is an essential way to minimize both the internal carrier transient time and RC-limited bandwidth. However, the miniaturized size of device usually results in serious device-heating and thermal failure under high-power operation. The primary source of self-heating is the input electrical power, which equals to the product of dc reverse bias of PD and its output photocurrent. To have the PD sustain high-speed and high-power performance even under zero-bias operation should thus be one of effective solutions to minimize this thermal issue. Uni-traveling carrier photodiodes (UTC-PDs), which have only fast electron as active carriers under small external applied electric field (~ 10 kV/cm), is one of attractive choices to meet the above-mentioned application under zero-bias operation. Such device structure has demonstrated an excellent 3-dB O-E bandwidth (>110 GHz) under 1.2 mA output photocurrent with a moderate saturation output power (-18.6 dBm at 2mA) at 100 GHz. In this work, we demonstrate a novel design of UTC-PD, which can further enhance its zero-bias performance. By using type-II (GaAs0.5Sb0.5/InP) absorption/collector interface and AlxInyGa1-x-yAs graded bandgap structure in the collector layer, the current blocking (Kirk) effect can be minimized. State-of-the-art high-speed performance (~140 GHz 3-dB O-E bandwidth at 2mA output photocurrent) and output power (-13.9 dBm at 8 mA) at sub-THz regime (160 GHz) under zero-bias operation has been successfully demonstrated.
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Heugen, Udo [Verfasser]. "Aufbau des THz-p-Germanium-Laser-Spektrometers zur Bestimmung des Einflusses von Sacchariden auf die Wasserdynamiken im Sub-Pikosekunden-Bereich / vorgelegt von Udo Heugen." 2007. http://d-nb.info/987533509/34.
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Alibakhshikenari, M., B. S. Virdee, C. H. See, Raed A. Abd-Alhameed, F. Falcone, and E. Limiti. "High-gain metasurface in polyimide on-chip antenna based on CRLH-TL for sub-terahertz integrated circuits." 2020. http://hdl.handle.net/10454/17985.
Full textAbstract:
YesThis paper presents a novel on-chip antenna using standard CMOS-technology based on metasurface implemented on two-layers polyimide substrates with a thickness of 500 μm. The aluminium ground-plane with thickness of 3 μm is sandwiched between the two-layers. Concentric dielectric-rings are etched in the ground-plane under the radiation patches implemented on the top-layer. The radiation patches comprise concentric metal-rings that are arranged in a 3 × 3 matrix. The antennas are excited by coupling electromagnetic energy through the gaps of the concentric dielectric-rings in the ground-plane using a microstrip feedline created on the bottom polyimide-layer. The open-ended feedline is split in three-branches that are aligned under the radiation elements to couple the maximum energy. In this structure, the concentric metal-rings essentially act as series left-handed capacitances CL that extend the effective aperture area of the antenna without affecting its dimensions, and the concentric dielectric rings etched in the ground-plane act as shunt left-handed inductors LL, which suppress the surface-waves and reduce the substrates losses that leads to improved bandwidth and radiation properties. The overall structure behaves like a metasurface that is shown to exhibit a very large bandwidth of 0.350–0.385 THz with an average radiation gain and efficiency of 8.15dBi and 65.71%, respectively. It has dimensions of 6 × 6 × 1 mm3 that makes it suitable for on-chip implementation.
This work is partially supported by RTI2018-095499-B-C31, Funded by Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER,UE), and innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424 and the fnancial support from the UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E022936/1.
Research Development Fund Publication Prize Award winner, March 2020