Dissertations / Theses on the topic 'Fréquences THz'
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Loghmari, Zeineb. "Lasers à cascades quantiques InAs / AISb au-delà de 10µm : émission mono-fréquence et génération du THz par différence de fréquences." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTS088.
Applications such as gas spectroscopy or medical imaging require light sources emitting in the mid- and far infrared (10 µm<λ < 28 µm) as well as in the THz (λ > 60µm). High-performance, continuous wave regime (CW) and single-frequency emission components are essential for this type of application. Quantum cascade lasers (QCLs) are the only sources that can cover this wide range of wavelengths thanks to their inter-sub-band transitions. However, the performance of LCQs in this wavelength range is often limited by non-radiative transitions. The latter generate mechanisms such as photon absorption by TO phonons or electron relaxation by LO phonons. As a result, laser emission in CW and at room temperature becomes particularly difficult. The objective of this thesis is the development of InAs/AlSb LCQs above 10 µm for single-frequency emission and THz generation by frequency difference. A key point in this work is the use of the InAs/AlSb material system. Their advantage is based on the low effective mass. It is 0.023m0 for InAs compared to 0.041m0 for InGaAs and 0.067m0 in GaAs.First, the development of LCQ active regions based on InAs/AlSb emitting at 11µm was carried out. This work made it possible to produce single-frequency DFB sources emitting continuously at 295K and which were used in QEPAS spectroscopy for ethylene sensing. This LCQ has also been transferred to Silicon (Si) substrate. He has demonstrated the world's most efficient LCQ grown directly on Si substrate. The wavelength range ≥ 11µm was also explored. First, by using a dielectric waveguide where this study leads to an active region design at 20µm whose performances exceed the state of the art in the world with continuous operation up to 240K. Then, these technologies were also exploited by using metal-metal waveguides. In this part, the limits of this waveguide were tested. This made it possible to produce a dual-frequency DFB CQL with a metal-metal waveguide emitting two wavelengths in the far infrared for the generation of THz by difference frequency. In this context, the non-linearity of this type of active region has been optimized. The extraction of the THz wave was also studied
Zakharenko, Olena. "Spectroscopie THz de molécules atmosphériques : application à l'étude de composés organiques volatils." Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10018/document.
We present the molecular spectroscopy results with the experimental developments and the analyses of high resolution spectra of molecules of atmospheric interest. We set up and tested a new frequency multiplication chain intended to extend the range of THz spectrometer in the PhLAM laboratory. The important parameters of the spectrometer, such as sensitivity, measurement precision and harmonic composition of the radiation source, were characterized using the rotational spectra of two simple molecules: formaldehyde and carbon monoxide. The extended analysis of rotational structure of HDCO, D2CO and 13C, 17O, 18O, and 13C18O isotopic species is also presented.Furthermore we studied the millimeterwave and terahertz rotational spectrum of 3 significant atmospheric molecules: methacrolein and methyl vinyl ketone, the main oxidation products of isoprene, and ethyl nitrite, a combustion product of alcohol based fuels and of photochemical oxidation of volatile organic compounds. These complex molecules are characterized by different large amplitude motions. In particular, the methyl group torsion was modeled in the experimental accuracy for the ground and the lowest excited vibrational states for methacrolein and methyl vinyl ketone. We thus provide an essential information for the detailed analysis of infrared spectra, recorded by high-resolution infrared spectroscopy, in the atmospheric windows
Cardenas, Nieto Jairo Ricardo. "Modélisation et optimisation de l’émission THz par des oscillations de Bloch." Paris 6, 2010. http://www.theses.fr/2010PA066383.
Bernard, Vincent. "Stabilisation en fréquence de lasers à CO² en dessous du Hertz : application à la métrologie des fréquences dans la région spectrale de 30 THz." Paris 6, 1997. http://www.theses.fr/1997PA066762.
Iskandar, Zyad. "Système de formation de faisceau dans la bande 300 GHz en technologie BiCMOS 55nm pour l’imagerie THz." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAT072/document.
The sub-millimeter wave band that covers the frequency range from 300 GHz to 3 THz has an interesting properties such the ability to penetrate materials. For THz imaging, it is possible to detect objects inside packages, clothes... With the evolution of integrated technologies and the increase of the cut-off frequencies of transistors 〖(f〗_t/f_max), many circuits and systems have been fabricated around 300 GHz, especially phased arrays for beamforming applications. These systems generate a signal and steer it electronically in a direction of the space. In this work, a novel architecture of phased array is proposed. It is based on the generation of a signal in the 270-300 GHz band, while controlling its phase by using phase shifters implemented in the LO path in the 45-50 GHz band. Each bloc should be measured in a stand-alone version, in order to get an idea about whole system performances. For this, the transmitter in the 270-300 GHz band has been realized first. It consists of a sub-harmonic injection locked oscillator, a passive mixer and IF amplifiers. Then, a novel architecture of phase shifter was proposed, it is based on slow waves coupled lines. Finally, a frequency multiplier chain was performed to generate the injection signal by using a lower frequency signal (3-5 GHz). The circuits are fabricated in a 55nm BiCMOS technology from STMicroelectronics. Measurements results are in a good agreement with simulations. Once the blocks are validated, sub systems are realized in order to validate one path of the array. The perspectives of this work include the design and realization of the complete phased array with multiple paths/antennas
Lai, Ngoc Diep. "Etude théorique et expérimentale des lasers solides bi-fréquences dans les domaines GHz à THz, en régime continu ou impulsionnel." Phd thesis, Rennes 1, 2003. https://tel.archives-ouvertes.fr/tel-00410958.
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.
Focusing 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
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.
The 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
Moron, Guerra José. "Design of Sub-THz heterodyne receivers in 65 nm CMOS process." Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10053/document.
The 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
Acef, Mohand Ouali. "Améliorations et comparaisons d'étalons de fréquences optiques : développement d'un spectromètre à très haute résolution autour de 28 THz et application à la spectroscopie de SF6." Paris 11, 1989. http://www.theses.fr/1989PA112052.
Pallas, Florent. "Etude théorique et expérimentale du fonctionnement bifréquence de microlasers continus et impulsionnels pour la génération d'ondes RF et THz." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00877894.
Leviandier, Thierry. "Modélisation Pluie-débit Durée Fréquence." Habilitation à diriger des recherches, Université Pierre et Marie Curie - Paris VI, 2008. http://tel.archives-ouvertes.fr/tel-00360116.
Une première partie traite de l'aspect spatial des transferts, visant à exprimer sous une forme très synthétique la structure arborescente du réseau hydrographique. Elle suffit à transcrire des effets d'échelle et les grands contrastes internes au bassin versant concernant la fonction de production, ce qui asseoit une méthode de régionalisation efficace. Une variante plus réaliste dans la représentation de l'hydraulique permet de représenter l'atténuation hydraulique au sein d'un bassin versant.
La modélisation stochastique de la pluie (CECP) procède par désagrégation de la pluie totale d'un épisode en sous épisodes. Cette décomposition \textit{quantité} x \textit{forme} permet d'utiliser des fonctions monotones à forme donnée, et donc d'inverser le modèle ou de calculer facilement des probabilités conditionnelles, opérations généralement impossibles avec d'autres modèles. Le modèle n'est donc pas restreint à une utilisation en simulation, mais permet un calcul explicite (numérique) des fréquences rares.
Les probabilités conditionnelles se révèlent par ailleurs une représentation conjointe des aspects dynamiques et probabilistes que l'on propose d'appeler modèle pluie-débit-durée-fréquence, et qui manifeste l'existence de durées critiques dépendantes de la fréquence. On propose par ailleurs une formulation approchée, sous forme de loi dérivée, c'est à dire une distribution de probabilité dont les paramètres sont les paramètres de la transformation pluie-debit.
Pour estimer ce modèle dans des conditions variées de disponibilité de l'information, on propose d'utiliser l'information de Kullback-Leibler, avec une adaptation pour les valeurs extrêmes.
Elmaleh, Coralie. "Développement d’un prototype ultrasensible d’analyse de gaz dans le domaine submillimétrique." Electronic Thesis or Diss., Littoral, 2024. http://www.theses.fr/2024DUNK0698.
This thesis explores the technological development of a spectroscopic experiment in the submillimeter range, also known as Terahertz (THz). This spectral band stands out for its ability to precisely resolve molecular doublets, enabling clear and precise identification of complex gas mixtures, even when other wavelengths might fail.Although the THz region offers exceptional resolving power, spectrometers operating in this region often face sensitivity challenges due to the development of technology in this band. Thanks to an innovative approach, we have implemented the first Cavity Ring-Down Spectroscopy (CRDS) experiment capable of quantifying compounds to ppb precision. The study is concentrated between 550 GHz and 650 GHz, a window of the THz spectrum that not only offers unrivalled resolution and molecular sensitivity, but also possesses the ability to penetrate non-conducting materials while being non-ionizing. These properties position this technology at the cutting edge of analysis tools, promising a plethora of applications, from fundamental research to industrial applications
Bourgeois, Pierre-Yves. "Référence Secondaire de Fréquence à Résonateur Saphir Cryogénique." Phd thesis, Université de Franche-Comté, 2004. http://tel.archives-ouvertes.fr/tel-00008331.
Bondu, François. "L'interféromètre Virgo :propriétés optiques, stabilisation en fréquence du laser." Habilitation à diriger des recherches, Université de Nice Sophia-Antipolis, 2008. http://tel.archives-ouvertes.fr/tel-00284986.
J'ai réalisé l'asservissement en fréquence du laser pour mesurer ces variations de temps de vol. La stabilité relative de fréquence en boucle du laser est de 1e-21 sur 100 ms ; je montre que le système obtenu respecte les spécifications. J'étudie dans le mémoire les propriétés d'un système où les boucles d'asservissements sont imbriquées.
Les cavités optiques résonnantes de l'interféromètre Virgo sont les éléments essentiels de la conversion d'une onde gravitationnelle. J'étudie l'ensemble des propriétés d'un oscillateur Fabry-Perot. Je montre comment elles peuvent être évaluées in situ à partir de mesures des fonctions de transfert utilisées pour leur verrouillage. Les cavités Fabry-Perot sont les oscillateurs de référence. Je fais un état des lieux de l'ensemble des perturbations susceptibles de perturber la stabilité de phase.
Abadie, Claire. "Détecteurs et lasers THz à base d'antennes accordables en fréquence." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS145/document.
Optoelectronic devices are crucial for many applications in everyday life: computers, smartphones, connected objects in general.The THz range (0.1-10 THz) still remains industrially unexploited because of the intrinsic difficulties to produce or generate THz photons. However, many applications exist for THz radiation : in the medical field for example, for the sensitive detection of gases, or for the imaging of concealed objects in the visible range.This thesis focuses on quantum well photodetectors (QWIPs) and quantum cascade lasers (QCLs) operating in the THz range in order to develop compact, fast and sensitive devices (but operating at cryogenic temperatures).We used Split Ring Resonators (SRR), inspired by metamaterial research, in order to design and develop subwavelength tunable THz detectors with an external inductance.Concerning lasers, this thesis studies THz micro-lasers using microdisk resonators with the aim of designing and manufacturing lasers operating on the fundamental electromagnetic mode (dipolar mode). The future perspective of this work is to build an entirely sub-wavelength and fast laser in the THz spectral range
Fosas, De Pando Miguel Ángel. "Génération d'ondes acoustiques à fréquences discrètes autour d'un profil d'aile : analyse de stabilité globale." Phd thesis, Ecole Polytechnique X, 2012. http://tel.archives-ouvertes.fr/tel-00816987.
Bonnin, Xavier. "Étude stéréoscopique de la directivité des sursauts radio solaires de type III aux fréquences inférieures à 10 MHz." Phd thesis, Université Paris-Diderot - Paris VII, 2008. http://tel.archives-ouvertes.fr/tel-00461521.
Alcouffe, Grégoire. "Production d'équivalents d'aérosols de l'atmosphère de Titan par plasma radio-fréquence." Phd thesis, Versailles-St Quentin en Yvelines, 2010. http://tel.archives-ouvertes.fr/tel-00597792.
Alcouffe, Grégoire. "Production d'équivalents d'aérosols de l'atmosphère de Titan par plasma radio fréquence." Phd thesis, Versailles-St Quentin en Yvelines, 2010. http://www.theses.fr/2010VERS0012.
The experiment prampre produces equivalents of aerosols of Titan's atmosphere thanks to a low pressure radio frequency plasma in a N2-CH4 gaseous mixture, representative of Titan's atmosphere, working in continuous or pulsed mode. The first goal of this work is to study the plasma. Electron density measurements, by microwave resonant cavity method, show this latter is lower in N2-CH4 mixtures than in pure N2. By optical emission spectroscopy, we show that this decrease in electron density is compensated by an increase in their energy. The second goal is a study of aerosols growth. Sem observations point out the influence of plasma parameters on the aerosols mean diameter between 300NM and 1µM. With 10S pulses, it is about 90NM, representative of Titan's aerosols. The pulsed mode shows that the formation time of aerosols is a few tens of seconds. This time is reduced at high pressure or at low amounts of CH4. At last, by measuring the polarization degree of the light of a 532NM laser beam scattered by aerosols, we can study their growth in situ and in real time. By comparing the measured polarization degree variations withe a mie-scattering model, we measure the evolution of aerosols mean radius and size distribution withe time. The obtained growth rates in radius of aerosols are about 4NM/S
Karbou, Fatima. "Inversion des mesures radiométriques haute-fréquence au-dessus des surfaces continentales." Phd thesis, Université de Versailles-Saint Quentin en Yvelines, 2004. http://tel.archives-ouvertes.fr/tel-00524882.
André, Nicolas. "ONDES ET INSTABILITÉS BASSE-FRÉQUENCE DANS UN PLASMA GYROTROPE. APPLICATION À L'INSTABILITÉ D'INTERCHANGE DANS LES MAGNÉTOSPHERES DES PLANETES GÉANTES." Phd thesis, Université Paul Sabatier - Toulouse III, 2003. http://tel.archives-ouvertes.fr/tel-00010486.
Afin de prendre en compte la nature des plasmas magnétosphériques, peu collisionnels, un formalisme exact d'étude linéaire des ondes et instabilités basse-fréquence dans les plasmas gyrotropes a été développé. Ce formalisme permet notamment de considérer les effets des forces non-électromagnétiques (force de gravitation, centrifuge et de Coriolis), les paramètres de la stratification (gradients et courbure) et certains effects cinétiques (résonance Landau).
Ce formalisme est dans un premier temps validé dans le cas des plasmas homogènes, avant d'être appliqué au cas des plasmas stratifiés. Les modes les plus influencés par la stratification du milieu, dénommés modes de quasi-interchange, y sont identifiés en termes de mode d'Alfvén, mode magnétosonore lent et mode miroir, suivant la terminologie classique en milieu homogène. Les critères d'instabilité des différents modes de quasi-interchange sont entièrement obtenus de manière analytique et sont appliqués au cas du plasma multi-espèces présent dans le tore de plasma du satellite Io de Jupiter, tel que décrit à travers les observations des sondes Voyager et Galileo.
Enfin, en attendant les observations de la mission Cassini en 2004 pour appliquer ces résultats dans l'environnement spatial de Saturne, son survol de Jupiter en décembre 2000 - janvier 2001 est présenté brièvement. L'analyse des données champ magnétique obtenues lors de ce survol nous permet de mettre en évidence profondément dans la magnétogaine jovienne des signatures observationnelles du mode miroir, identifié auparavant à l'aide de notre formalisme théorique.
Kessouri, Pauline. "Mesure simultanée aux fréquences moyennes et cartographie de la permittivité diélectrique et de la conductivité électrique du sol." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00787908.
Lasne, Y. "Imagerie radar basse fréquence pour l'exploration des zones arides terrestres et martiennes : détection de l'humidité du sous-sol et cartographie de la paléohydrologie." Phd thesis, Université Paul Sabatier - Toulouse III, 2005. http://tel.archives-ouvertes.fr/tel-00320160.
Illig, Serena. "Variabilité basse fréquence de l'Atlantique Tropical:Rôle de la dynamique océanique équatoriale et Influence d'El Niño Southern Oscillation." Phd thesis, Université Paul Sabatier - Toulouse III, 2005. http://tel.archives-ouvertes.fr/tel-00260664.
Schmeissner, Roman. "Frequency combs at the quantum limit." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066699.
Precision metrology is one application of optical frequency combs. Classical noise in their properties typically limits achievable measurement sensitivity. Amplitude and phase noise in optical frequency combs have already been studied extensively. So far, noise sidebands close to the carrier of either individual optical frequencies or of the mean field were considered. This thesis develops methods to precisely characterize amplitude and phase noise down to the quantum limit. To this aim a transmissive, broadband passive cavity is developed. It filters and inter-converts amplitude and phase noise. The analysis of its signal by the use of homodyne detection provides a quantum limited measurement of phase noise. The application of ultrafast pulse shaping enables the measurement of the spectral correlations of amplitude and phase noise. Being represented by the use of covariance matrices, the entire noise correlations over the optical spectrum are characterized on the example of a Ti:Sapph oscillator. The measured noise correlations exhibit spectral structures, so-called “modes”. Their shape matches with the theoretical prediction. This concept known from multi-partite optical quantum systems is consequently applicable to classical noise in frequency combs. The knowledge of the intrinsic noise modes is likely provide an improvement of precision metrology experiments with combs
Lasne, Yannick. "Imagerie radar basse fréquence pour l'exploration des zones arides terrestres et martiennes : détection de l'humidité du sous-sol et cartographie de la paléohydrologie." Phd thesis, Université Paul Sabatier - Toulouse III, 2005. http://tel.archives-ouvertes.fr/tel-00180231.
Puigt, Mathieu. "Méthodes de séparation aveugle de sources fondées sur des transformées temps-fréquence. Application à des signaux de parole." Phd thesis, Université Paul Sabatier - Toulouse III, 2007. http://tel.archives-ouvertes.fr/tel-00270811.
Nous avons tout d'abord étudié et amélioré des méthodes proposées précédemment par l'équipe, basées sur des critères de variance ou de corrélation, pour des mélanges linéaires instantanés. Elles apportent d'excellentes performances pour des signaux de parole et peuvent aussi séparer des spectres issus de données astrophysiques. Cependant, la nature des mélanges qu'elles peuvent traiter limite leur champ d'application.
Nous avons donc étendu ces approches à des mélanges plus réalistes. Les premières extensions considèrent des mélanges de sources atténuées et décalées temporellement, ce qui correspond physiquement aux mélanges en chambre anéchoïque. Elles nécessitent des hypothèses de parcimonie beaucoup moins fortes que certaines approches de la littérature, tout en traitant le même type de mélanges. Nous avons étudié l'apport de méthodes de classification non-supervisée sur nos approches et avons obtenu de bonnes performances pour des mélanges de signaux de parole.
Enfin, une extension théorique aux mélanges convolutifs généraux est décrite mais nécessite de fortes hypothèses de parcimonie et le réglage d'indéterminations propres aux méthodes fréquentielles.
Le, Quilliec Guénhaël. "Application du martelage à haute fréquence à l'optimisation de la maintenance des ouvrages et des structures soudées." Phd thesis, Ecole Centrale de Nantes (ECN), 2011. http://tel.archives-ouvertes.fr/tel-00961736.
Aurino, Mario. "Réseaux de bolomètres à électrons chauds supraconducteurs à haute Tc en ondes terahertz : avancées technologiques." Paris 6, 2009. http://www.theses.fr/2009PA066328.
Moro, Melgar Diego. "Conception et optimisation de la tête haute fréquence d'un récepteur hétérodyne à 1.2 THz pour l'instrument JUICE-SWI." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066618/document.
The design, fabrication and testing of a frequency heterodyne receiver at 1.2 THz has been developed by Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères (LERMA) and it is the foundation of this dissertation. The studies, analysis and results presented in this manuscript have been carried out within the framework of the JUpiter ICe moon Explorer (JUICE) mission. JUICE is one of the proposed missions in the agenda of the European Space Agency (ESA) Cosmic Vision 2015-2025 program. The objective of the JUICE satellite mission is to study the Jovian system, especially the Jupiter atmosphere properties and the surface characteristics of its icy moons. Scientific equipment consisting of ten state-of-the-art instruments and one experiment comprise the payload of this satellite. The development of a 1.2 THz channel is part of the Submillimeter Wave Instrument (SWI) devoted to recovering the spectroscopy data of the Jupiter atmosphere and icy-moons’ surface composition. The scientific principle for this receiver is all-solid-state semiconductor technology based in GaAs Planar Schottky Barrier Diodes (PSBDs). The achievement of a 1.2 THz channel based in PSBDs totally developed by European partners was the major challenge proposed for SWI, with LERMA committed to this assignment. The required ultra-scaling of the Schottky anode size of PSBDs in the attainment of the THz range has been achieved in collaboration with Laboratoire de Photonique et de Nanostructures (LPN) using e-beam photolithography in the fabrication of Monolithic Microwave Integrated Circuits (MMIC). An important part of this dissertation addresses the appearance of additional physical phenomena when ultrascaling solid-state PSBDs. Particularly, the modification of the electrical resistivity and capacitance of SBDs due to two-dimensional phenomena has been studied by means of a physical microscopic Two-Dimensional Monte Carlo (2D-MC) simulator, in collaboration with the University of Salamanca, Salamanca, Spain. As discussed within this manuscript, the accurate characterization of the diode capacitance is one of the critical points when opening a frequency window in the required frequency range of a THz application. A misunderstanding of this modified capacitance during the design of these devices can lead to a considerable offset in the frequency range of the experimental module. However, the accurate modeling of PSBDs in such high frequency applications is only a part of the expertise required for the successful completion of this challenge. The accurate and meticulous analysis of the interrelationship between the electromagnetic behavior of the MMIC chip and the physical behavior of the integrated PSBDs is the main challenge faced in this dissertation for the development of the 1.2 THz receiver. This task has been addressed using the commercial Ansys High Frequency Simulation/Structure Software (Ansys-HFSS) and the Keysight Advance Design System (Keysight-ADS). The combination of the three-dimensional electromagnetic characterization of the chip structure (obtained with HFSS) with the non-linear electrical circuit simulation (carried out by ADS) of diodes is the current methodology for the design of these modules. The analytical electrical model of PSBDs required by ADS software has been defined by this author in agreement with the results obtained with the 2D-MC simulator. The implementation of this approach in the design and optimization of the different stages of the accomplished 1.2 THz receiver is the main subject of this dissertation. The interaction between the physical model of the PSBDs and the electromagnetic modeling of the structure will be discussed within the different chapters of this dissertation. Finally, the mechanical engineering of these applications must be addressed in this discussion
Thébault, Julien. "La coquille de Comptopallium radula (Bivalvia; Pectinidae), archive eulérienne haute-fréquence de la variabilité de l'environnement côtier tropical (Océan Pacifique)." Phd thesis, Université de Bretagne occidentale - Brest, 2005. http://tel.archives-ouvertes.fr/tel-00012033.
Ce travail de thèse porte sur l'utilisation de la coquille de Comptopallium radula, un mollusque bivalve tropical de la famille des Pectinidae, pour reconstruire la variabilité de l'environnement dans le lagon sud-ouest de Nouvelle-Calédonie, un écosystème sous l'influence de diverses perturbations (réchauffement climatique, urbanisation, exploitation minière). Cette étude repose sur la comparaison de données géochimiques archivées dans la coquille de ce pectinidé au cours de sa vie, avec plusieurs variables physiques, chimiques et biologiques mesurées dans le lagon (suivi environnemental hebdomadaire). L'objectif de cette approche est de calibrer et de mettre en œuvre différents proxies climatiques et environnementaux.
Des marquages à la calcéine, effectués in situ sur des individus juvéniles, ont tout d'abord permis de démontrer que les stries de croissance présentes à la surface externe de la coquille de C. radula se forment avec une périodicité de 2 jours.
Des analyses isotopiques (δ18O et δ13C) ont ensuite été effectuées à partir de micro-échantillons de calcite prélevés le long de l'axe de croissance maximale de 6 coquilles juvéniles. Connaissant la périodicité de formation des stries, une date calendaire a pu être attribuée avec précision à chacun de ces prélèvements (résolution hebdomadaire). Nos résultats démontrent que les variations ontogéniques du δ18Ocalcite permettent de reconstruire les variations de la température de l'eau avec une précision de 1 °C. Quant à la composition isotopique du carbone (δ13Ccalcite), elle ne peut pas être utilisée comme proxy de la production primaire pélagique. Ses variations sont vraisemblablement contrôlées par le métabolisme benthique (sédiment et coraux).
Suite à ces analyses isotopiques, des analyses élémentaires ont été effectuées sur les mêmes coquilles à l'aide d'un système d'ablation laser couplé à un spectromètre de masse à plasma induit (LA-ICP-MS). Nos résultats démontrent que C. radula, au travers des concentrations en métaux dans sa coquille, ne peut être utilisé comme outil de bio-surveillance des apports en métaux dans le lagon : les variations ontogéniques de ces concentrations reflètent probablement les variations temporelles haute-fréquence des flux de métaux à l'interface eau-sédiment. Quant au baryum et au molybdène, leurs concentrations coquillières pourraient être utilisées comme proxies des biomasses de diatomées et de diazotrophes, respectivement.
Cette étude démontre donc le potentiel considérable de la coquille de C. radula comme archive eulérienne haute-fréquence de la variabilité climatique et environnementale dans le lagon sud-ouest de Nouvelle-Calédonie. Elle met également en lumière l'importance des processus benthiques sur l'incorporation des signaux géochimiques dans la matrice calcitique de la coquille. Son utilisation en tant qu'outil paléocéanographique est désormais conditionnée par la découverte de gisements fossiles de l'espèce.
Heggy, Essam. "Etude et modélisation des performances des radars sondeurs basse fréquence pour la recherche de l'eau dans le sous-sol de Mars." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2002. http://tel.archives-ouvertes.fr/tel-00011598.
Mikael, Ali. "Evaluation des paramètres physiques des bâtiments : amortissement, fréquence et modes de comportement des structures de génie civil : approche expérimentale." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00597269.
Ma, San Zhou. "Etude des phénomènes transitoires d'ondes à haute fréquence dans les postes blindés à THT à l'héxafluorure de soufre." Ecully, Ecole centrale de Lyon, 1988. http://www.theses.fr/1988ECDL0017.
Nyobe, Yome Jean-Maurice. "Contribution à la modélisation des transformateurs HT et THT alimentés en fréquence variable par convertisseurs statiques à multirésonance." Montpellier 2, 1993. http://www.theses.fr/1993MON20234.
CASTELLTORT, Sébastien. "Origine et modification des cycles stratigraphiques à haute-fréquence (10's à 100's ka). Rôle des déformations courte longueur et modélisation du comportement des systèmes fluviatiles." Phd thesis, Université Rennes 1, 2003. http://tel.archives-ouvertes.fr/tel-00003936.
Gélis, Céline. "Inversion des formes d'onde élastique dans le domaine espace-fréquence en deux dimensions.Application à la caractérisation de la subsurface dans le cadre de la détection de cavités souterraines." Phd thesis, Université de Nice Sophia-Antipolis, 2005. http://tel.archives-ouvertes.fr/tel-00199493.
Le problème direct associé, la propagation des ondes élastiques, est résolu dans le domaine fréquentiel, permettant la prise en compte efficace d'acquisitions multisources et multirécepteurs, par une méthode numérique de différences finies modélisant la propagation de tous les types d'onde (ondes de volume, de surface, diffractées, réfractées ...). Le stencil de différences finies choisi permet simule précisément la surface libre et la propagation des ondes de surface.
Cette inversion linéarisée s'appuie sur une méthode de gradient, qui minimise une fonction coût contenant les différences entre données observées et calculées. Deux paramètres sismiques sont reconstruits à partir de sismogrammes verticaux et horizontaux. L'inversion est effectuée des basses fréquences vers les hautes fréquences, introduisant des longueurs d'onde de plus en plus courtes dans les images des paramètres. Ces dernières sont sensibles au choix des approximations physiques effectuées pour calculer le gradient de la fonction coût (approximation de Born ou de Rytov), au dispositif d'acquisition, au préconditionnement des données et au choix des paramètres inversés.
Cette méthode est ensuite appliquée à des milieux contenant une surface libre. La surface libre est une interface très contrastée qui donne lieu à des ondes de surface très énergétiques dans les sismogrammes. Les milieux de subsurface sont complexes, les ondes qui s'y propagent subissent des réflexions ou diffractions multiples. Lorsque le milieu contient deux anomalies dont le contraste en vitesse vaut $20 \%$, l'inversion les localise correctement dans un macromodèle connu. Les images sont améliorées et l'amplitude des anomalies est très bien reconstruite lorsque le nombre de fréquences inversées augmente et les données sont sélectionnées des faibles déports vers les grands déports. Avec une anomalie fortement contrastée comme une cavité vide, l'inversion retrouve correctement la position, la forme et la taille de l'objet mais son amplitude est sous-estimée.
L'application à des données réelles verticales de subsurface acquises dans un milieu complexe contenant une cavité maçonnée montre que le milieu hétérogène issu de l'inversion ajuste mieux les données et permet de bien reproduire les ondes inversées. Néanmoins, la cavité n'est pas imagée.
Adelinet, Mathilde. "Du terrain au laboratoire, étude des propriétés élastiques du basalte." Phd thesis, Université du Maine, 2010. http://tel.archives-ouvertes.fr/tel-00672425.
Cardenas, Olaya Andrea. "Digital instrumentation for the measurement of high spectral purity signals." Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCD019/document.
Improvements on electronic technology in recent years have allowed the application of digital techniques in time and frequency metrology where low noise and high accuracy are required, yielding flexibility in systems implementation and setup. This results in measurement systems with extended capabilities, additional functionalities and ease of use.The Analog to Digital Converters (ADCs) and Digital to Analog Converters (DACs), as the system front-end, set the ultimate performance of the system in terms of noise. Moreover, most commercial platforms based on FPGA are clocked by quartz oscillators whose accuracy and frequency stability are not suitable for many time and frequency applications. In this case, it is possible to take advantage of the internal Phase Locked Loop (PLL) for generating the internal clock from an external frequency reference. However, the PLL phase noise could degrade the oscillator stability thereby limiting the entire system performance becoming a critical component for digital instrumentation. The information available currently in literature, describes in depth the features of these devices at frequency offsets far from the carrier. However, the information close to the carrier is a more important concern for time and frequency applications.In this frame, my PhD work is focused on understanding the limitations of the critical blocks of digital instrumentation for time and frequency metrology. The aim is to characterize the noise introduced by these blocks and in this manner to be able to predict their effects on a specific application. This is done by modeling the noise introduced by each component and by describing them in terms of general and technical parameters. The parameters of the models are identified and extracted through the corresponding method proposed accordingly to the component operation. This work was validated by characterizing a commercially available platform, Red Pitaya. This platform is an open source embedded system whose resolution and speed (14 bit, 125 MSps) are reasonably close to the state of the art of ADCs and DACs (16 bit, 350 MSps or 14 bit, 1 GSps/3GSPs) and it is potentially sufficient for the implementation of a complete instrument. The characterization results lead to the noise limitations of the platform and give a guideline for instrumentation design techniques.Based on the results obtained from the noise characterization, the implementation of a digital instrument for frequency transfer using fiber link was performed on the Red Pitaya platform. In this project, a digital implementation for the detection and compensation of the phase noise induced by the fiber is proposed. The beat note, representing the fiber length variations, is acquired directly with a high speed ADC followed by a fully digital phase detector. Based on the characterization results, it was expected a limitation in the phase noise measurement given by the PLL. First measurements of this implementation were performed using the 150 km-long buried fibers, placed in the same cables between INRiM and the Laboratoire Souterrain de Modane (LSM) on the Italy-France border. The two fibers are joined together at LSM to obtain a 300 km loop with both ends at INRiM. From these results the noise introduced by the digital system was verified in agreement with characterization results. Further test and improvements will be performed for having a finished system which is intended to be used on the Italian Link for Frequency and Time from Turin to Florence that is 642-km long and to its extension in the rest of Italy that is foreseen in the next future.Currently, a higher performance platform is under assessment by applying the tools and concepts developed along the PhD. The purpose of this project is the implementation of a state of the art phasemeter whose architecture is based on the DAC. The DAC characterization is under development and preliminary measurements are reported here
Collombon, Mathieu. "Résonance noire à trois photons sur un nuage d'ions calcium confinés." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0017.
The work presented in this thesis describes the complete experimental set-up and approach to realize three-photon coherent population trapping in a cloud of radiofrequency confined calcium ions. The realization of such a population trapping relies on a stringent conditions of the phase relationship between the three lasers involved in the interrogation process, and also their spectral linewidths. Our experimental approach is based on the optimization of the performance of a frequency-stabilized titanium-sapphirelaser at 411 THz (729nm) at the 10⁻¹⁴ level, in term of relative frequency uncertainties. This laser’s fre-quency stability is subsequently transfered to a optical frequency comb by means of a phase-locked loop. Then the two other lasers involved (866 nm and 794 nm) are phase-locked to the optical frequency combwith the same technique. This work describes the transfer method along with its measured performances. With all the three lasers sharing the same ultra-stable frequency reference we have been able to experi-mentally observe for the first time a 3-photon dark resonance in the fluorescence spectra of the 40 Ca⁺, signature of a coherent population trapping in a 3-photon scheme. The dependence of this resonance at experimental parameters, such as laser powers, laser detunings and local magnetic field, have been studied and are presented in this work. The preliminary results have allowed to explain the behaviour of the dark resonance and explored conditions for the use of the 3-photon dark line as a THz frequency standard
Jangal, Florent. "Apport de la bipolarisation, du traitement adaptatif du signal et de la multirésolution à l'élimination du fouillis ionosphérique pour les radars haute fréquence à ondes de surface." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2007. http://tel.archives-ouvertes.fr/tel-00257608.
Maze, Guillaume. "Interactions Basses Frequences Ocean-Atmosphere dans l'Ocean Austral." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2006. http://tel.archives-ouvertes.fr/tel-00515553.
Ait, Allal Dalal. "Détection d'évènements impulsionnels en environnement radioélectrique perturbé : application à l'observation des pulsars intermittents avec un système temps réel de traitement du signal." Phd thesis, Université d'Orléans, 2012. http://tel.archives-ouvertes.fr/tel-00840256.
Bunel, Morgane. "Recherche de gènes impliqués dans des rétinopathies canines comme modèles de rétinites pigmentaires humaines." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1B019/document.
Dogs are affected by numerous genetic diseases including retinopathies, the subject of my thesis. Historically, humans have exerted a very strong artificial selection to dogs, thus creating some 400 breeds to perform specific tasks or to harbour specific traits. By such an homogenisation of phenotypic and behavioural traits, humans have selected desired alleles but also concentrated undesired deleterious alleles responsible of genetic diseases. These diseases are clinically and genetically similar to human genetic diseases, making dogs a model of choice to search for the genetic bases of such genetic diseases and to develop new therapies for a mutual benefit for dogs and humans. I worked on Progressive Retinal Atrophies (PRA) in two breeds, thanks to the contribution of the veterinary ophthalmologist Dr. Gilles Chaudieu and the breed clubs of border collies and berger picard. Concerning the border collie PRA, genetic analyses performed before my thesis allowed the identification of a locus of 20Mb on the X chromosome. I first completed and supplemented the epidemiological and clinical data for about 500 dogs and continued the sample and data collection. A first genetic linkage analysis on 130 dogs allowed to confirm the transmission mode and the locus. I then performed several genetic analyses (« homozigosity mapping », genotypes analyses, candidate gene sequencing) without significantly reducing the locus,neither finding the causal mutation, unfortunately. In this context and thanks to the development of new sequencing technologies, I chose to sequence the entire genome of three PRA affected border collies and two unaffected related dogs. This work allowed the identification of 117variants, 9 in the locus but none in coding regions. I thus focused my research on genetic variants from potential regulatory regions for 13 candidate genes. In addition, I identified five structural variants. The analysis of these variants is still ongoing. Concerning the berger picard PRA, we have re-initiated the project by collecting samples and designing a large pedigree of 154 dogs. This workled to an international collaboration by the sequencing of the entire genomes of 2 affected and 2 unaffected bergers picards for which the statistical analyses are ongoing. This thesis allowed me to work on the genetics of rare diseases in humans with a spontaneous and original animal model and even if thiswork has not yet reached the identification of the mutations, these two PRAs in these two breeds remain good genetic and therapeutic models for human RP RetinitisPigmentosa
Serradas, Viegas Mendonça Tiago. "Influence of the activities imposed by the human being on equine emotional responses." Thesis, Toulouse, INPT, 2020. http://www.theses.fr/2020INPT0020.
Humans have made profits from equine activities, which evolved through times. Horses worked as transport facilitator, become an advantage in times of war and are athletes in many sport disciplines. Nowadays, horses are involved in therapies to improve human medical conditions as well. Horses are often involved in different equestrian disciplines or work activities, which require a great adaptation capacity of the animal. Therefore, horses’ implication in diverse activities may probably be the reason for the variability of equine emotional responses (either positive or negative). Equine emotional responses to different activities can be investigated using behavioural and physiological indicators of emotions. The aim of this thesis was to study the influence of some activities imposed by humans in horses’ emotional responses. The investigation of novel physiological indicators (biological ones) that may play a role in emotional responses (e.g. oxytocin) was also an aim of this thesis. Results from this thesis demonstrated that equine emotional responses vary according to the activity in which horses are involved. Lateral exercises were beneficial for the emotional states of horses involved in different equestrian disciplines (dressage, jumping, eventing). Equine-assisted therapy did not produce negative nor positive emotions. Sport horses (Chilean rodeo) differed from working horses (urban draught work) in their emotional responses to a specific stimulus. Different plasma levels of free oxytocin were associated with different equine activities. These results disclose many perspectives and research questions. Equine emotional responses should be investigated within each equestrian discipline or work activity separately. Training/working methods investigations may reveal innovative solutions to improve equine welfare. Further investigation on biological indicators (positive or negative) is still needed
Necciari, Thibaud. "Auditory time-frequency masking : Psychoacoustical measures and application to the analysis-synthesis of sound signals." Aix-Marseille 1, 2010. http://www.theses.fr/2010AIX1A100.
Many audio applications, such as sound analysis-synthesis tools or audio codecs, call for specifie signal representations enabling the analysis, processing, and synthesis of non stationary signals. Most of them are concerned with time-frequency (TF) representations such as the Gabor and wavelet transforms that allow decomposing any real-world sound into a set of elementary functions (or "atoms") well localized in the TF domain. On the purpose of adapting these representations to the human auditory perception, the present study investigated auditory masking in the TF domain. Masking has been extensively investigated with simultaneous (frequency masking) and non-simultaneous (temporal masking) presentation of masker and target. A few studies examined TF relations of masking between masker and target. Because those studies involved stimuli that are not maximally compact in the TF plane (. E. , they were temporally and/or spectrally broad), their results are not suitable for predicting masking effects between TF atoms. In this study, we investigated auditory TF masking with masker and target signals having minimum spread in the TF plane, namely Gaussian-shaped sinusoids (referred to as Gaussians). The masker had a carrier frequency of 4 kHz and a level of 60 dB SL. Masker and target were separated either in frequency, in time, or bath. The results of the TF conditions provide the TF spread of masking for stimuli that are maximally concentrated in the TF domain. The results of the simultaneous and non-simultaneous conditions allowed to show that a simple superposition of frequency and temporal masking functions does not provide an accurate representation of the measured TF masking function for Gaussian maskers. Two additional experiments were carried out that examined the effects of masker level and masker frequency in simultaneous conditions. Decreasing the masker level from 60 to 30 dB SL resulted in a reversal of the masking patterns' asymmetry and a narrowing of the frequency spread of masking. The frequency spread of masking at 0. 75 kHz was similar to that obtained at 4 kHz when compared on an ERB scale. This is compatible with the constant-Q frequency analysis by the human auditory system. Finally, a first attempt was made to implement the gathered masking data in a sound signal processing algorithm allowing to remove the perceptually irrelevant atoms in the TF representations of audio signals. Potential applications of such an approach are, for instance, audio codees and sound analysis-synthesis tools
Cexus, Jean-Christophe. "Analyse des signaux non-stationnaires par transformation de Huang, opérateur de Teager-Kaiser et transformation de Huang-Teager (THT)." Rennes 1, 2005. http://www.theses.fr/2005REN1S124.
Quintana, Adrien. "Modification d'expression de NR2B lors de dyskinésies de la patte avant chez le rat induites par traitement chronique à la L-DOPA ou par stimulation à haute fréquence du Noyau Subthalamique." Thesis, Grenoble, 2011. http://www.theses.fr/2011GRENV031.
High frequency stimulation of the subthalamic nucleus (STN-HFS) alleviates parkinsonian motor symptoms and indirectly improves dyskinesia by decreasing L-DOPA requirement. However, inappropriate stimulation can also trigger dyskinetic movements Dyskinesia are thought to be a pathological learning process due to an overactive glutamate transmission within the basal ganglia. Moreover, several molecular changes seem to be involved in this process. The aim of the present study is to compare the molecular mechanisms of dyskinesia induced by L-DOPA and by STN-HFS, by focusing more particularly on the NR2B-containing NMDA receptor. We show by immunohistochemistry that NR2B subunit is hyperphosphorylated within the STN and the EP during a dyskinesiogenic STN-HFS in normal rats. Similar results are obtained from 6-OHDA rats, a model of Parkinson disease. Comparison of these results with those observed in 6-OHDA dyskinetic rats chronically treated with L-DOPA suggest that dyskinesia induction is associated with an hyperphosphorylation of NR2B within a subthalamo-entopeduncular network while activation of NR2B within the striatum seem to be involved in the expression of dyskinesia. A different implication of the two output of the basal ganglia in akinetic and dyskinesiogenic process is also demonstrated. STAR Date de soutenance : 8 juillet 2011 Thèse sur travaux: non
Schuhler, Nicolas. "Frequency-comb stabilized laser sources for absolute distance metrology at the very large telescope interferometer." Université Louis Pasteur (Strasbourg) (1971-2008), 2006. https://publication-theses.unistra.fr/public/theses_doctorat/2006/SCHUHLER_Nicolas_2006.pdf.
The forthcoming instrument of the Very Large Telescope Interferometer (VLTI), called Phase-Referenced Imaging and Micro-arcsecond Astrometry facility (PRIMA), uses a laser metrology system to monitor the variations of internal path lengths. This dissertation addresses the development, integration and test of frequency stabilized laser sources for the PRIMA Metrology system (PRIMET). In the first part, we present in the context of PRIMA and the VLTI the specifications of PRIMET. We recall the basics of single-wavelength laser interferometry and introduce the problems raised by its application to PRIMET. We present the need for the absolute frequency stabilization of PRIMET laser and the interest for an upgrade of PRIMET towards absolute distance measurements. In the second part, we present our contribution to the absolute frequency stabilization of PRIMET Nd:YAG laser on a transition of iodine. We characterize the system and measure precisely its performance with a self-referenced optical frequency comb. We improve the system to reach the specifications in terms of accuracy and stability of the locking frequency. The third part addresses the upgrade of PRIMET towards absolute distance measurements by the use of two-wavelength interferometry. We propose a new concept of two-wavelength laser source frequency stabilized on an optical frequency comb. This permits the generation of an unprecedented large choice of synthetic wavelength with a relative accuracy better than 10−11 in vacuum. We validate the concept on a prototype and shows that it can be used to resolve an optical wavelength. Finally, we propose to apply this concept to the upgrade of PRIMET