Dissertations / Theses on the topic 'Multimode light'
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1
Wang, Qi. "Studies of multimode fibre linked white light interferometric sensor systems." Thesis, City University London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389649.
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Zheng, Zhan. "Two-photon--two-atom excitation with quantum multimode light states." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066589/document.
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Deux photons - deux atomes (2P2A) excitation s’avère être un banc de test importantde propriétés optiques quantiques. Depuis 1980, on sait que la probabilité de transition2P2A peut être grandement améliorée en utilisant la source monochromatique cohérenteavec la présence d’interactions atomiques qui induisent un pic de résonance de 2P2A. En2004 , Muthukrishnan et al. sont trouvés une grande amélioration de la transition ainsique d’une résonance de 2P2A, quand une source de deux photons intriqués, provenant dela radiation d’un atome cascade à trois niveaux, interagit avec les deux atomes différentsde l’ interaction. Leur conclusion est que : dans certaines situations, l’intrication peutremplacer un vrai hamiltonien d’interaction, qui est une déclaration de grande portée etune propriété importante liée à l’intrication. Ce phénomène mérite plus d’attention et defavoriser la compréhensionTwo-photonÐtwo-atom (2P2A) excitation turns out to be an important test bench of quantum optical properties. In 2004, Muthukrishnan et al. announced a great enhancement of the transition at 2P2A resonance, when an entangled two-photon state, coming from a three-level cascade, interacts with two non-interacting atoms. Their conclusion: in some situations, entanglement can replace a real interaction Hamiltonian, reveals an important property related to entanglement. In this thesis, We study in detail the efficiency of various multimode two-photon states of light to induce the simultaneous excitation of two atoms of different kinds under 2P2A resonance condition. We find that several separable, correlated states, produced either by an atomic cascade or parametric down-conversion, or even appropriate combinations of coherent states, have comparable efficiencies as the photon state produced by an atomic cascade. We conclude that the true physical origin of the enhancement is the frequency anti-correlations, neither the temporal correlations, time ordering, nor entanglement. To present, we are not sure whether or not the enhancement is a quantum effect. We also studied: 1. the optimized 2P2A transition probability for a given photon spectrum; 2. the influence coming from finite lifetimes of the excited detecting atoms; 3. the 2P2A transition probability in the presence of atomic interaction
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Ning, Ya Nong. "A study of optical fibre interferometric systems using multimode laser diode light sources." Thesis, City University London, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316037.
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Wickenbrock, A. "Cold atoms in light fields : from free space optical lattices to multimode optical cavities." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1349525/.
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The electromagnetic mode density of the vacuum can be dramatically modified by the presence of an optical resonator. In the strong coupling regime, spontaneous emission in a cavity becomes a reversible process and the intracavity photon number undergoes Rabi oscillations. We load up to 200x10^3 ^133Cs atoms into a nearly confocal lossy cavity and reach the collective strong coupling regime. Normal mode splitting, the hallmark of this regime, is observed and cooperativities up to C_coll = (186±5) are measured. In a second experiment we investigate for the first time the multi-mode character of the coupled cavity-atom system. In a confocal cavity the higher-order transverse cavity modes are degenerate in frequency and accessible to the spontaneous emission of the atomic ensemble. We observe an increase of the coupling constant measured via modal decomposed transmission analysis, which could be attributed to the presence of the higher-order modes. Normal mode splitting proportional to the square root of the atom number was visible for all of the different mode components. Furthermore, we observe a redistribution of the relative weights in the modal transmission composition, which scales with the atom number in the cavity mode. In a second set of experiments, ^87Rb atoms were loaded into a dissipative lin ⊥ lin lattice. By driving the lattice with a biharmonic force, transport can be observed when the systems symmetries are broken: the so called ratchet effect. Research in this area is concerned with the appearance of current reversals. We were able to identify dissipation related symmetry breaking as the underlying cause of an observed current reversal, which occurs as a function of the driving frequency. Furthermore, in a second experiment, we use the ratchet effect as a probe of the optical potential depths. We show that an oscillating force with a frequency far above any other system-inherent timescale, can be used to renormalize the optical potential. The ^87Rb atoms experience an average position dependent force, which becomes controllable over the amplitude of the applied driving.
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Leedumrongwatthanakun, Saroch. "Quantum information processing with a multimode fibre." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS526.
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Le transport à haut débit de données à travers des fibres optiques grâce au multiplexage spatial est en pratique limité par la diaphonie modale. Au lieu de considérer ce couplage modal comme une limitation, nous exploitons ici ce mélange de modes comme une ressource. Nous mettons en oeuvre un réseau optique linéaire programmable basé sur le concept de design photonique inverse, exploitant les techniques de mise en forme du front d’onde. Nous démontrons la manipulation d’interférences quantiques à deux photons sur divers réseaux linéaires, comprenant des degrés de liberté spatiaux et de polarisations. En particulier, nous vérifions expérimentalement la « zero transmission law » dans des interféromètres de Fourier et de Sylvester, permettant de quantifier le degré d’indiscernabilité d’un état d’entrée. De plus, grâce à la possibilité de mettre en oeuvre un réseau non unitaire, nous mettons en évidence l’anti-coalescence de photons dans toutes les configurations de sortie, et réalisons une expérience d’absorption cohérente. Nous démontrons ainsi l’aspect reconfigurable de l’implémentation de tels réseaux optiques linéaires dans des fibres multimodes. De plus, nous étudions les propriétés statistiques du speckle à un et à deux photons générés à partir de divers états d’entrée, après propagation dans une fibre multimode. Ces propriétés statistiques du speckle peuvent être utilisées pour extraire des informations sur la dimensionnalité, la pureté et l’indiscernabilité d’un état quantique inconnu, permettant ainsi leur classification. Ce travail met en évidence le potentiel du contrôle de front d’onde en milieux complexes pour le traitement quantique de l’informationTransport of information through a multimode optical fibre raises challenges when one wants to increase the data traffic using many spatial modes due to modal cross-talk and dispersion. Instead of considering those complex mixing of modes as a detrimental process, in this dissertation, we harness its mode mixing to process quantum optical information. We implement a reconfigurable linear optical network, a fundamental building block for scalable quantum technologies, based on an inverse photonic approach exploiting the technology of wavefront shaping. We experimentally demonstrate manipulation of two-photon quantum interference on various linear optical networks across both spatial and polarization degrees of freedom. In particular, we experimentally show the zero-transmission law in Fourier and Sylvester interferometers, which are used to certificate the degree of indistinguishability of an input state. Moreover, thanks to the ability to implement a non-unitary network, we observe the photon anti-coalescence effect in all output configurations, as well as the realization of a tunable coherent absorption experiment. Therefore, we demonstrate the reconfigurability, accuracy, scalability and robustness of the implemented linear optical networks for quantum information processing. Furthermore, we study the statistical properties of one-and two-photon speckles generated from various ground-truth states of light after propagating through a multimode fibre. These statistical properties of speckles can be used to extract information about the dimensionality, purity, and indistinguishability of an unknown input state of light, therefore allowing for state classification. Our results highlight the potential of complex media combined with wavefront shaping for quantum information processing
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Heinrich, Georg [Verfasser], and Florian [Akademischer Betreuer] Marquardt. "Nanomechanics interacting with light: Dynamics of coupled multimode optomechanical systems / Georg Heinrich. Betreuer: Florian Marquardt." Erlangen : Universitätsbibliothek der Universität Erlangen-Nürnberg, 2011. http://d-nb.info/101763923X/34.
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Neo, Poh Ling. "Increasing the transmission capacities of a multimode fibre transmission link using a spatial light modulator." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612421.
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Chille, Vanessa. "Quantum optics with structured light." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066358/document.
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La présente thèse a pour objectif d'analyser la lumière structurée non-classique et ses caractéristiques. L'optique quantique et la lumière structurée sont deux sujets qui font l'objet d'examens nombreux. Ils sont néanmoins rarement examinés en combinaison. Les propriétés quantiques de la lumière structurée sont moins bien étudiées qu'ils devraient l'être. Par la lumière structurée nous entendons les champs lumineux qui montrent une structure transverse complexe de l'intensité, la phase ou la polarisation. Nous voulons lier les deux sujets de l'optique quantique et la lumière structurée dans la présente thèse. Dans ce but, nous générons expérimentalement des champs lumineux structurés non-classiques. En particulier, nous réalisons une expérience qui permet de générer des faisceaux vectoriels vectoriels - c'est-à-dire des faisceaux lumineux dont l'état de polarisation présente une structure transverse complexe - qui montrent une réduction du bruit quantique. En outre, nous étudions théoriquement les propriétés spatiales de faisceaux lumineux, ainsi que leur bruit. Plus spécifiquement, nous analysons l'incertitude quantique dans la largeur d'un faisceau lumineux. Pour prouver la faisabilité de la vérification expérimentales de nos résultats théoriques, nous réalisons des simulations pour la mesure de paramètres spatiales utilisant un détecteur mulitpixelsThis thesis aims at learning more about nonclassical structured light. Quantum optics and structured light are two topics that are subject to countless scientific examinations. However, they are very rarely combined and the quantum properties of structured light are not as thoroughly studied as they deserve. By structured light, we mean any light fields with complex transverse distributions of intensity, phase or polarization. We want to link the topics of quantum optics and structured light in this thesis. For this purpose, we experimentally generate particular nonclassical structured light fields. In particular, we construct an experimental setup that enables us, in principle, to produce arbitrary amplitude squeezed vector beams, i.e. light beams with a complex transverse structure of the state of polarization. Furthermore, we analyze spatial properties of light beams, and their quantum noise theoretically. We specifically perform theoretical examinations of the quantum noise in the width of a light beam. To show the feasibility of an experimental verification of our theoretical results, we conduct simulations for the measurement of spatial parameters of a beam's cross-section by a multipixel detector
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Zhao, Xin. "Study of Multimode Extrinsic Fabry-Perot Interferometric Fiber Optic Sensor on Biosensing." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/34534.
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The electrostatic self-assembly (ESA) method presents an effective application in the field of biosensing due to the uniform nanoscale structure. In previous research, a single mode fiber (SMF) sensor system had been investigated for the thin-film measurement due to the high fringe visibility. However, compared with a SMF sensor system, a multimode fiber (MMF) sensor system is lower-cost and has larger sensing area (the fiber core), providing the potential for higher sensing efficiency.
In this thesis, a multimode fiber-optic sensor has been developed based on extrinsic Fabry-Perot interferometry (EFPI) for the measurement of optical thickness in self-assembled thin film layers as well as for the immunosensing test. The sensor was fabricated by connecting a multimode fiber (MMF) and a silica wafer. A Fabry-Perot cavity was formed by the reflections from the two interfaces of the wafer. The negatively charged silica wafer could be used as the substrate for the thin film immobilization scheme. The sensor is incorporated into the white-light interferometric system. By monitoring the optical cavity length increment, the self-assembled thin film thickness was measured; the immunoreaction between immunoglobulin G (IgG) and anti-IgG was investigated.
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Czarske, Jürgen W., Daniel Haufe, Nektarios Koukourakis, and Lars Büttner. "Perspectives of multimode fibers and digital holography for optogenetics." SPIE, 2016. https://tud.qucosa.de/id/qucosa%3A34836.
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Optogenetic approaches allow the activation or inhibition of genetically prescribed populations of neurons by light. In principle, optogenetics offers not only the ability to elucidate the functions of neural circuitry, but also new approaches to a treatment of neurodegenerative diseases and recovery of vision and auditory perception. Optogenetics already has revolutionized research in neuroscience. However, new methods for delivering light to three-dimensionally distributed structures e.g. in the brain are necessary. A major hurdle for focusing light through biological tissue is the occurring scattering and scrambling of the light. We demonstrate the correction of the scrambling in a multimode fiber by digital optical phase conjugation with a perspective for ptogenetics.
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Wang, K. "Design, measurement and analysis of multimode light guides and waveguides for display systems and optical backplane interconnections." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1435557/.
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The aim of the research in this thesis was to design and model multimode lightguides for optimising visible light for liquid crystal display systems and to design, model and experimentally test infrared light propagation within polymer multimode waveguides as board-to-board interconnects for high data rate communication. Ray tracing models the behaviour of a novel LCD colour separating backlight to optimize its efficiency by establishing the optimum dimensions and position for a unique micro-mirror array within the light guide. The output efficiency increased by 38.2% compared to the case without the embedded mirror array. A novel simulation technique combined a model of liquid crystal director orientation and a non-sequential ray tracing program was used first time to compute the reflected intensity from a LCOS device for a rear projection TV system. The performance of the LCOS display was characterised by computing the contrast ratio over a ±15° viewing cone. Photolithographically manufactured embedded multimode waveguides made from acrylate Truemode® polymer are characterized by measuring the optical transmission loss of key waveguide components including. straight, bend and crossing. Design rules derived from the experimental measurement were used to optimize optical PCB (OPCB) layout. A most compact and complex optical interconnects layout up-to-date for data centres, including parallel straight waveguide sections, cascaded 90° bends and waveguide crossing other than 90° angles, was designed, tested and used in an optic-electrical demonstration platform to convey a 10.3 Gb/s data. A further new method for reducing the end facet roughness and so the coupling loss, by curing a thin layer of core material at the end of the waveguide facet to cover the roughness fluctuations, was proposed and successfully demonstrated giving the best results reported to date resulting in an improvement of 2.8 dB which was better than the results obtained by using index matching fluid.
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Tovar, Anthony Alan. "Off-axis multimode light beam propagation in tapered lenslike media including those with spatial gain or loss variation." PDXScholar, 1988. https://pdxscholar.library.pdx.edu/open_access_etds/3839.
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The propagation of light beams in inhomogeneous dielectric media is considered. The derivation begins with first principles and remains general enough to include off-axis asymmetric multimode input beams in tapered lenslike media with spatial variations of gain or loss. The tapering of lenslike media leads to a number of important applications. A parabolic taper is proposed as a model for a heated axially stretched fiber taper, and beams in such media are fully characterized. Other models are proposed by the concatenation of a parabola with other taper functions.
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Gouzien, Élie. "Optique quantique multimode pour le traitement de l'information quantique." Thesis, Université Côte d'Azur (ComUE), 2019. http://www.theses.fr/2019AZUR4110.
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Cette thèse étudie l’optique quantique multimode, aussi bien du point de vue de la génération que celui de la détection. Elle s’articule autour de trois volets. Nous étudions la génération de lumière comprimée multimode dans une cavité. Pour cela nous considérons la forme la plus générale de hamiltonien quadratique, permettant entre autres de décrire l’utilisation de plusieurs pompes dans un matériau effectuant du mélange à quatre ondes. Une approche combinant fonctions de Green et décompositions de matrices symplectiques est décrite. Cette théorie générique est appliquée à des cas particuliers. Dans un premier temps, des exemples en basse dimension sont donnés. Ensuite, une configuration d’oscillateur paramétrique optique pompé de manière synchrone (SPOPO) est décrite et étudiée ; les résultats obtenus montrent que ce système a un comportement très différent de celui du SPOPO utilisant une non-linéarité d’ordre 2. Ces travaux ouvrent la voie à la réalisation de peignes de fréquences quantiques avec des micro-résonateurs en anneau gravés sur silicium. Un autre problème examiné est celui de prendre en compte l’information temporelle obtenue lors du clic d’un détecteur de photon unique. Pour cela nous utilisons un formalisme multimodal temporel afin d’expliciter les opérateurs décrivant la mesure. Les principaux défauts des détecteurs réels, dont la gigue temporelle, l’efficacité finie et les coups d’obscurité sont pris en compte. L’utilisation des opérateurs est illustrée par la description d’expériences usuelles de l’optique quantique. Enfin, on montre que la lecture du temps de clic du détecteur permet d’améliorer la qualité de l’état généré par une source de photons annoncés. En troisième partie nous présentons un schéma de génération d’intrication hybride entre variables continues et discrètes, pour laquelle la partie discrète est encodée temporellement. Ce schéma est analysé en détail vis-à-vis de sa résistance aux imperfections expérimentalesThis thesis studies multimode quantum optics, from generation to detection of light. It focuses on three main parts. Multimode squeezed states generation within cavity is studied. More specifically, we take into account general quadratic Hamiltonian, which allows describing experiments involving arbitrary number of modes and pumps within a medium performing four-wave mixing. We describe a generic approach combining Green functions and symplectic matrix decomposition. This general theory is illustrated on specific cases. First, low-dimensional examples are given. Then, a synchronously pumped optical parametric oscillator (SPOPO) is described and studied; it shows a very distinct behavior from that of the SPOPO using second order non-linearity. This work opens way to the realization of quantum frequency combs with ring micro-resonators engraved on silicon. Single-photon detectors are described taking into account temporal degrees of freedom. We give positive-valued measurement operators describing such detectors including realistic imperfections such as timing-jitter, finite efficiency and dark counts. Use of those operators is illustrated on common quantum optics experiments. Finally, we show how time-resolved measurement allows improving the quality of state generated by single-photon heralded source. In the third part we propose a protocol for generating a hybrid state entangling continuous and discrete variables parts, for which the discrete part is time-bin encoded. This scheme is aanalysed in detail with respect to its resilience to experimental imperfections
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Sperber, Tom. "Control of light in a disordered medium with gain : wavefront-shaping the pump in fiber amplifiers and fiber lasers." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS366.
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L'émergence récente des techniques de façonnage spatial a démontré la possibilité de contrôler la propagation de la lumière à travers des milieux désordonnés, telles que des fibres multimodes. Le cas particulier d'une fibre multimode à gain présente une complexité supplémentaire, car la pompe, elle-même multimode, peut agir sur le signal dans des profils d'amplification spatialement complexes. Le gain hétérogène résultant est donc équivalent à un processus de diffusion non unitaire. Ces systèmes peuvent trouver leur applications plusieurs domaines, notamment les communications optiques, les lasers à fibre de haute puissance, et les lasers aléatoires. Dans ce travail, nous considérons une fibre multimode dopée par un élément de terre rare et pompée par une pompe cohérent dont le faisceau passe par un schéma de mise en forme de front d’onde. Cette architecture nous permet de configurer la composition modale de l’excitation dans la fibre. Nous explorons la possibilité d'exploiter les degrés de liberté ainsi offerts dans le pompage pour contrôler le signal en sortie. Un modèle théorique et son implémentation numérique permettent de quantifier les degrés de contrôle réalisable, tout en révélant les mécanismes fondamentaux qui les limitent. Dans une configuration d’amplificateur, les expériences ont permis de valider les prédictions du modèle en montrant un effet significatif du façonnage de la pompe sur le speckle à la sortie de l’amplificateur. Dans une configuration de la cavité d'effet laser, les travaux expérimentaux ont démontré la capacité du schéma de modulation de favoriser les modes laser choisisThe recent advent of wavefront-shaping techniques has demonstrated the ability to control the propagation of light through a broad range of complex media, amongst them multimode fibers. The case of a multimode fiber which is also a gain medium presents increased complexity, since the pump beam, in itself multimode, may act upon the signal light in speckle-like spatial profiles of amplification. The resulting heterogeneous gain may be viewed as analogous to a non-unitary scattering process. Interest in the study of such systems has recently risen in several domains, such as optical communications, high-power fiber lasers, and random lasers. In this work, we consider a multimode fiber doped by a rare-earth element, and pumped by a coherent pump beam that passes through a wave-front shaping scheme, rendering the modal composition of the excitation within the fiber configurable. We explore the possibility of harnessing the degrees of freedom thus offered in the pumping, for controlling the output signal of such a gain system. A theoretical model and its implementation as a numerical solver serve to quantify the degree of achievable control, as well as providing insights into the fundamental mechanisms limiting it. In an amplifier configuration, the experimental work successfully validated the model’s predictions by showing a significant effect of the wave-front shaping of the pump upon the speckle at the amplifier’s output. In the lasing cavity configuration, the experimental work demonstrated the ability of the pump modulation scheme to influence the lasing emission, in particular to favor or suppress chosen lasing modes
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Al-Mamun, Mohammad Shah. "Development of a Miniature, Fiber-optic Temperature Compensated Pressure Sensor." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/71308.
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Since the invention of Laser (in 1960) and low loss optical fiber (in 1966) [1], extensive research in fiber-optic sensing technology has made it a well-defined and matured field [1]. The measurement of physical parameters (such as temperature and pressure) in extremely harsh environment is one of the most intriguing challenges of this field, and is highly valued in the automobile industry, aerospace research, industrial process monitoring, etc. [2]. Although the semiconductor based sensors can operate at around 500oC, sapphire fiber sensors were demonstrated at even higher temperatures [3].
In this research, a novel sensor structure is proposed that can measure both pressure and temperature simultaneously. This work effort consists of design, fabrication, calibration, and laboratory testing of a novel structured temperature compensated pressure sensor. The aim of this research is to demonstrate an accurate temperature measurement, and pressure measurement using a composite Fabry-Perot interferometer. One interferometer measures the temperature and the other accurately measures pressure after temperature compensation using the temperature data from the first sensor.Master of Science
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Perret, Solveig. "Génération de lumière Supercontinuum dans le visible et l’ultraviolet dans des fibres optiques multimodes de silice dopée à saut d'indice." Thesis, Bourgogne Franche-Comté, 2020. http://www.theses.fr/2020UBFCD024.
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Bien que la propagation non-linéaire d'impulsions multimodales ait été étudiée dans les fibres optiques multimodes depuis les années 1970, les récents développements dans le domaine des matériaux et des techniques de fabrication des fibres ont considérablement renouvelé l'intérêt pour ce domaine. Dans cette thèse, nous rapportons l'étude expérimentale du processus de conversion non-linéaire de fréquence dans les fibres à saut d'indice multimodes pour générer de nouvelles composantes spectrales dans les régions du proche ultraviolet (UV-A) et du visible. Deux études particulières ont été réalisées. Dans la première, une fibre à saut d'indice faiblement multimode a été étudiée avec deux sources laser à 532~nm et 1064~nm. En fonction des particularités des conditions expérimentales, les résultats obtenus avec le pompage à 532~nm ont donné soit un large continuum multimode s'étendant de 515~nm à 680~nm, soit une série de composantes spectrales discrètes émises dans des modes d'ordre supérieur sur la plage de 524~nm à 538~nm. De plus, toujours en fonction des conditions expérimentales, lors du pompage à 1064~nm, les expériences ont donné soit un supercontinuum multimode s'étendant de 560~nm à 2350~nm, soit une série de pics spectraux discrets dans des modes d'ordre supérieur observés simultanément avec un élargissement spectral continu. Dans la seconde étude, les expériences ont porté sur la conversion non-linéaire de fréquences dans une fibre à cristaux photoniques en verre de silice spéciale UV avec pompage à 532~nm et 355~nm. Les résultats du pompage à 355 nm, en particulier, ont permis de générer des pics spectraux discrets d'ordre supérieur sur la plage 350~nm à 379.7~nm. D'autres expériences avec une injection dans les ponts de la microstructure de la fibre à cristaux photoniques ont permis d'obtenir un continuum en cascade Raman s'étendant de 350~nm à 390~nm. Les travaux expérimentaux de cette thèse ont été accompagnés soit de calculs théoriques des accords de phase intermodaux, soit de simulations de la propagation d'impulsions dans une fibre optique, si nécessaire. Cette thèse contribue à l'ensemble croissant de résultats montrant l'utilité des effets non-linéaires dans les fibres multimodes pour générer un rayonnement cohérent sur de larges plages spectralesAlthough multimode non-linear propagation has been studied in multimode optical fibres since the 1970s, recent developments in materials and manufacturing techniques have greatly renewed interest in this area. In this thesis, we report the experimental study of nonlinear frequency conversion processes in multimode fibres to generate new spectral components in the near ultraviolet (UV-A) and visible spectral regions. Two particular studies have been carried out. In the first, a few-mode step-index fibre was studied with two pump laser sources at 532~nm and 1064~nm. Depending on the particular experimental conditions, the results with 532~nm pumping yielded either a broad multimode continuum spanning over 515--680~nm, or as series of discrete spectral components emitted in particular higher-order modes over the range 524--538~nm. And again depending on experimental conditions, when pumping at 1064~nm, experiments yielded either a broadband multimode continuum spanning over 560--2350~nm, or a series of discrete spectral peaks in higher-order modes observed simultaneously with continuous spectral broadening. In the second study, experiments studied nonlinear frequency conversion in a UV-grade silica glass photonic crystal fibre with pumping at 532~nm and 355~nm. Results for 355~nm pumping in particular yielded the generation of higher-order mode discrete spectral peaks over the range 350--379.7~nm. Additional experiments pumping the photonic crystal fibre microstructure cladding region yielded a Raman cascade continuum spanning 350--390~nm. The experimental work in this thesis was accompanied by theoretical calculations of intermodal phase matching, or simulations of pulses propagation in an optical fibre as required. This thesis contributes to the growing body of results showing the utility of nonlinear effects in multimode fibre to generate coherent radiation over broad spectral ranges
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Verrier, Isabelle. "Influence de certains paramètres sur la propagation lumineuse dans les fibres optiques : fluctuations d'intensité en sortie de fibre multimodale." Saint-Etienne, 1988. http://www.theses.fr/1988STET4008.
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L'étude de flux lumineux lors d'un couplage fibre-fibre a permis d'évaluer, en lumière incohérente et cohérente, l'énergie couplée, les fluctuations et le rapport signal sur bruit. Ce travail a amené alors à considérer les variations d'intensité en sortie de fibre sous influence d'une courbure et de modéliser les répartitions de puissance lumineuse en fonction de cette contrainte
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Zanzi, Andrea. "Passive and active silicon photonics devices at TLC telecommunication wavelengths for on-chip optical interconnects." Doctoral thesis, Universitat Politècnica de València, 2020. http://hdl.handle.net/10251/149377.
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[EN] Optical technologies are the backbone of modern communication systems providing
high-speed access to the Internet, efficient inter and intra-data center interconnects
and are expending towards growing research fields and new markets such as satel-
lite communications, LIDARs (Laser Imaging Detection and Ranging) applications,
Neuromorphic computing, and programable photonic circuits, to name a few. Be-
cause of its maturity and low-cost, silicon photonics is being leveraged to allow these
new technologies to reach their full potential.As a result, there is a strong need for
innovative, high-speed and energy-efficient photonic integrated building blocks on
the silicon platform to increase the readiness of silicon photonic integrated circuits.
The work developed and presented in this thesis is focused on the design and char-
acterization of advanced passive and active devices, for photonic integrated circuits.
The thesis consists of three main chapters as well as a motivation and concluding
sections exposing the rationale and the accomplishments of this work. Chapter one
describes the design and characterization of an electro-optical Mach-Zehnder mod-
ulator embedded in highly efficient vertical pn junction exploiting the free-carrier
dispersion effect in the O-band.. Chapter two is devoted to the design and charac-
terization of a novel geometry of asymmetrical multimode interference device and
its implementation in a Mach-Zehnder modulator. Chapter three is dedicated to
the design and characterization of innovative 1-dimensional photonic crystal designs
for slow- lightmodulation applications. An extensive analysis of the main trade-off
arising from the use of slow light is presented.[ES] Las tecnologías ópticas son el eje vertebrador de los sistemas de comunicación mod- ernos que proporcionan acceso de alta velocidad a la Internet, interconexiones efi- cientes entre centros de datos y dentro de ellos. Además, se están expandiendo hacia campos de investigación crecientes y nuevos mercados como son las aplicaciones de comunicaciones por satélite, los LIDAR (Laser Imaging Detection and Ranging), la computación neuromórfica y los circuitos fotónicos programables, por nombrar algunos. La fotónica de silicio está considerada y aceptada ampliamente como una de las tecnologías clave para que dichas aplicaciones puedan desarrollarse. Como resultado, hay una fuerte necesidad de estructuras fotónicas básicas integradas que sean innovadoras, que soporten altas velocidades de transmisión y que sean más eficientes en términos de consumo de potencia, a fin de aumentar la capacidad de los circuitos integrados fotónicos de silicio. El trabajo desarrollado y presentado en esta tesis se centra en el diseño y la car- acterización de dispositivos avanzados pasivos y activos, para circuitos fotónicos integrados. La tesis consta de tres capítulos principales, así como de sendas sec- ciones de motivación y conclusiones que exponen los fundamentos y los logros de este trabajo. El capítulo uno describe el diseño y la caracterización de un modulador electro-óptico Mach-Zehnder incorporado en una unión pn vertical altamente eficien- ciente que explota el efecto de dispersión de plasma en banda O. El capítulo dos está dedicado al diseño y caracterización de una nueva geometría de dispositivo de interferencia multimodo asimétrico y su aplicación en un modulador Mach-Zehnder. El capítulo tres está dedicado al diseño y caracterización de innovadores cristales fotónicos unidimensionales para aplicaciones de modulación con luz lenta. Se pre- senta un amplio análisis de los principales retos derivados del uso de la misma.
[CA] Les tecnologies òptiques són l'eix vertebrador d'aquells sistemes de comunicació moderns que proporcionen accés d'alta velocitat a la Internet, així com intercon- nexions eficients inter i entre centres de dades. A més a més, s'estan expandint cap a camps d'investigació creixents i nous mercats com són les aplicacions de co- municacions per satèl·lit, els LIDAR (Laser Imaging Detection and Ranging), la computació neuromòrfica i els circuits fotònics programables, entre d'altres. La fotònica de silici és considerada i acceptada àmpliament com una de les tecnologies clau i necessàries perquè aquestes aplicacions puguen desenvolupar-se. Per aquest motiu, es fa necessària l'existència d'estructures fotòniques bàsiques integrades que siguen innovadores, que suporten altes velocitats de transmissió i que siguen més eficients en termes de consum de potència, a fi d'augmentar la capacitat dels cir- cuits integrats fotònics de silici. El treball desenvolupat i presentat en aquesta tesi se centra en el disseny i la caracterització de dispositius avançats passius i actius, per a circuits fotònics integrats. La tesi consta de tres capítols principals, així com d'una secció de motivació i una altra de conclusions que exposen els fonaments i els assoliments d'aquest treball. El capítol u descriu el disseny i la caracterització d'un modulador electro-òptic Mach-Zehnder incorporat en una unió pn vertical d'alta efi- ciència que explota l'efecte de dispersió de plasma en la banda O. El capítol dos està dedicat al disseny i caracterització d'una nova geometria de dispositiu d'interferència multimode asimètric així com a la seua aplicació en un modulador Mach-Zehnder. El capítol tres està dedicat al disseny i caracterització d'innovadors cristalls fotònics unidimensionals per a aplicacions de modulació amb llum lenta. S'inclou també una anàlisi detallada dels principals reptes derivats de l'ús d'aquest tipus de llum.
I want to thank you the Generelitat Valenciana and the European Project L3MATRIX for the funding, without them my doctorate would not taken place.
Zanzi, A. (2020). Passive and active silicon photonics devices at TLC telecommunication wavelengths for on-chip optical interconnects [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/149377
TESIS
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Štolzová, Hana. "Analýza limitů zobrazování multimodovými optickými vlákny." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-392838.
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Multimódová vlákna jsou zobrazovacím prostředkem s významným potenciálem v in-vivo mikroendoskopii. V poslední době tato metoda zaznamenala velký rozvoj, a to díky zdokonalování výpočetní a jiné techniky, například prostorové modulace světla. Cílem této práce bylo nalézt specifické limity zobrazování multimódovými vlákny a představit jejich počítačovou simulaci. Byl zkoumán vliv způsobu osvětlení optického systému obsahujícího multimódové vlákno na jeho schopnost fokusace a zobrazování. Analýzou dat získaných ze simulací a experimentu bylo zjištěno, že různá míra omezení Gaussovského svazku a plnění apertury multimódového vlákna má za následek významnou změnu zobrazovacích schopností systému. Při pozorování kvality fokusace bylo zjištěno, že nejlépe se projevují svazky málo omezené aperturou vlákna. Tento fakt byl potvrzen i experimentálním měřením. Zobrazování za použití svazků s podobnými hodnotami omezení (50%) projevovalo i nejlepší schopnost přenosu kontrastu. Avšak při analýze rozlišení dvou bodových objektů se jako nejvhodnější projevily svazky významně přeplňující numerickou aperturu vlákna, 100% a více. Přítomnost tohoto rozdílu poukazuje na skutečnost, že multimódové vlákno není zcela náhodné médium, ale propagace světla skrz multimódové vlákno projevuje znaky závislosti na vnějších zobrazovacích podmínkách, jako je například změna omezení osvětlovacího svazku. V této práci bylo představeno několik způsobů vyhodnocení kvality zobrazování pomocí multimódového vlákna. Každé z těchto kritérií podalo dílčí charakteristiku chování optického systému obsahujícího multimódové optické vlákno. Jednotlivé výsledky se neshodují na jednom konkrétním řešení a nutí osobu využívající zobrazovací systém obsahující multimódové vlákno ke zvážení několika aspektů, a to v jakém prostředí bude daný optický systém využívat a který parametr kvality zobrazení bude považovat za nejdůležitější.
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Yusuf, Isse Jamila, and Ghouch Chaimae El. "Information Theoretic Similarity Measures for Robust Image Matching : Multimodal Imaging - Infrared and Visible light." Thesis, KTH, Teoretisk datalogi, TCS, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-186450.
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Abstract This study aimed to investigate the applicability of three different information theoretic similarity measures in image matching, mutual information (MI), cross-cumulative residual entropy (CCRE) and sum of conditional variances (SCV). An experiment was conducted to assess the impact on the performances of the similarity measures when dealing with multimodality, in this case in the context of infrared and visible light. This was achieved by running simulations of four different scenarios using images taken in infrared and visible light, and additionally with variations in amount of details to create different experimental setups. Namely experimental setup A: unimodal data sets with more and less details and experimental setup B: multimodal datasets with more and less details. The result showed that the concept of multimodality gives a statistically significant effect on the performances of all similarity measures. Observations were made that the similarity measures performances also, when trying to match images with different amount of details, differed from each other. This provided a basis for judgement on what measure to use as to give as clear and sound results as possible depending on the variation of detail amount in the data. With this study, it was concluded that the similarity measure CCRE gave the most clear and sound results in the context of multimodality concerning infrared and visible light for both cases of more or less details. Even though the other similarity measures performed well in some cases, CCRE would be to recommend as observed by this study. Keywords : Image matching, image registration, information theoretic similarity measures, multimodal imaging, similarity measures, MI, CCRE, SCV, infrared, visible light.Denna studie syftade till att undersöka tillämpligheten av tre olika informationsteoretiska likhetsmått vid matchning av bilder, mutual information (MI), cross cumulative residual entropy (CCRE) och sum of conditional variances (SCV). Ett experiment genomfördes för att bedöma hur de olika likhetsmåtten påverkades i kontexten av multimodalitet, i detta fall i samband med infrarött och synligt ljus. Detta uppnåddes genom att köra simuleringar av fyra olika scenarier med hjälp av bilder tagna i infrarött och synligt ljus, och dessutom med variationer i mängden detaljer för att skapa olika experimentella uppsättningar. Nämligen experimentuppsättning A: unimodala datamängder med mer / mindre detaljer och experimentuppsättning B: multimodala datamängder med mer / mindre detaljer. Resultatet visade att multimodalitet har en statistiskt signifikant påverkan på alla likhetsmått. Observationer gjordes att likhetsmåttens beteenden, när man försöker matcha bilder med olika mängd detaljer, skilde sig från varandra. Detta gav en grund för bedömning av vilken av dessa likhetsmått som då kunde användas för att ge de mest tydliga och stabila resultaten som möjligt beroende på variationen av mängden detaljer i datat. Med denna studie drogs slutsatsen att likhetsmåttet CCRE gav mest de tydliga och stabila resultaten i samband med multimodalitet gällande infrarött och synligt ljus för båda fallen av mer eller mindre detaljer. Även om de andra likhetsmåtten också gav goda resultat i vissa fall, skulle CCRE vara att rekommendera, som observerat i denna studie.
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Toledo, Acosta Bertha Mayela. "Multimodal image registration in 2D and 3D correlative microscopy." Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1S054/document.
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Cette thèse porte sur la définition d'un schéma de recalage automatique en microscopie corrélative 2D et 3D, en particulier pour des images de microscopie optique et électronique (CLEM). Au cours des dernières années, la CLEM est devenue un outil d'investigation important et puissant dans le domaine de la bio-imagerie. En utilisant la CLEM, des informations complémentaires peuvent être collectées à partir d'un échantillon biologique. La superposition des différentes images microscopiques est généralement réalisée à l'aide de techniques impliquant une assistance manuelle à plusieurs étapes, ce qui est exigeant et prend beaucoup de temps pour les biologistes. Pour faciliter et diffuser le procédé de CLEM, notre travail de thèse est axé sur la création de méthodes de recalage automatique qui soient fiables, faciles à utiliser et qui ne nécessitent pas d'ajustement de paramètres ou de connaissances complexes. Le recalage CLEM doit faire face à de nombreux problèmes dus aux différences entre les images de microscopie électronique et optique et leur mode d'acquisition, tant en termes de résolution du pixel, de taille des images, de contenu, de champ de vision et d'apparence. Nous avons conçu des méthodes basées sur l'intensité des images pour aligner les images CLEM en 2D et 3D. Elles comprennent plusieurs étapes : représentation commune des images LM et EM à l'aide de la transformation LoG, pré-alignement exploitant des mesures de similarité à partir d'histogrammes avec une recherche exhaustive, et un recalage fin basé sur l'information mutuelle. De plus, nous avons défini une méthode de sélection robuste de modèles de mouvement, et un méthode de détection multi-échelle de spots, que nous avons exploitées dans le recalage CLEM 2D. Notre schéma de recalage automatisé pour la CLEM a été testé avec succès sur plusieurs ensembles de données CLEM réelles 2D et 3D. Les résultats ont été validés par des biologistes, offrant une excellente perspective sur l'utilité de nos développementsThis thesis is concerned with the definition of an automated registration framework for 2D and 3D correlative microscopy images, in particular for correlative light and electron microscopy (CLEM) images. In recent years, CLEM has become an important and powerful tool in the bioimaging field. By using CLEM, complementary information can be collected from a biological sample. An overlay of the different microscopy images is commonly achieved using techniques involving manual assistance at several steps, which is demanding and time consuming for biologists. To facilitate and disseminate the CLEM process for biologists, the thesis work is focused on creating automatic registration methods that are reliable, easy to use and do not require parameter tuning or complex knowledge. CLEM registration has to deal with many issues due to the differences between electron microscopy and light microscopy images and their acquisition, both in terms of pixel resolution, image size, content, field of view and appearance. We have designed intensity-based methods to align CLEM images in 2D and 3D. They involved a common representation of the LM and EM images using the LoG transform, a pre-alignment step exploiting histogram-based similarities within an exhaustive search, and a fine mutual information-based registration. In addition, we have defined a robust motion model selection method, and a multiscale spot detection method which were exploited in the 2D CLEM registration. Our automated CLEM registration framework was successfully tested on several real 2D and 3D CLEM datasets and the results were validated by biologists, offering an excellent perspective in the usefulness of our methods
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Kandoth, Noufal. "Design, Synthesis and Characterization of Photoactivable Cyclodextrin-Based Nanoparticles for Multimodal Anticancer Therapy." Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1280.
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Abstract
The general goal of this thesis is the development of new generation photoactivable smart nanomaterials that can be modulated into tremendous way to achieve multimodal anticancer and antimicrobial therapeutic actions. Here the cyclodextrins act as the building block for the development of the nanocarrier in order to convey the therapeutic payload to the desired site. With this goal in mind, we have developed several kinds of nanosystems and are discussed in each chapter. The entire dissertation is divided into four sections based on the types of materials and the sections are further divided into twelve chapters based on the functional behavior of each nanosystems.
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Ob'yedkova, Ekaterina. "Multimodal Environmental Interfaces : discrete and continuous changes of form, light, and color using natural modes of expression." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/91410.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Architecture, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (page 75).
In this thesis, I defined and implemented a framework for design and evaluation of Multinodal Environmental Interfaces. Multimodal Environmental Interfaces allow users to control form, light, and color using natural modes of expression. The framework is defined by categorizing possible changes as discrete or continuous. Discrete and continuous properties of form, light, and color can be controlled by speech, gestures and facial expressions. In order to evaluate advantages and disadvantages of each of the modalities, I designed and conducted a series of experiments. I disproved my hypothesis that whereas discrete changes are easier to control with language, continuous changes are easier to control with gestures and facial expressions through a series of interactive prototypes. I proved my hypothesis that the perception of whether a gesture or a speech command feels intuitive is consistent among the majority of users.
by Ekaterina Ob'yedkova.
S.M.
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Hott, Robert Shawn. "Re-tooling an American metropolis." [Tampa, Fla.] : University of South Florida, 2010. http://digital.lib.usf.edu/?e14.3368.
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Thesis (M.Arch.)--University of South Florida, 2010.Title from PDF of title page. Document formatted into pages; contains 155 pages. The content of this file may cause problems when attempting to access it through some versions of the Internet Explorer or Firefox browser. Recommended browsers for accessing this file are Internet Explorer 8, Opera, Safari, or Chrome on Windows; Firefox, Opera, or Safari on Macs. Includes bibliographical references.
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Hannachi, Ammar. "Imagerie multimodale et planification interactive pour la reconstruction 3D et la métrologie dimensionnelle." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAD024/document.
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La fabrication de pièces manufacturées génère un nombre très important de données de différents types définissant les géométries de fabrication ainsi que la qualité de production. Ce travail de thèse s’inscrit dans le cadre de la réalisation d’un système de vision cognitif dédié à l’évaluation d’objets 3D manufacturés incluant éventuellement des surfaces gauches, en tenant compte des tolérances géométriques et des incertitudes. Ce système permet un contrôle exhaustif de pièces manufacturées et offre la possibilité d’une inspection tridimensionnelle automatique de la pièce. La mise en place d’un système de mesures multi-capteurs (passifs et actifs) a permis d’améliorer significativement la qualité d’évaluation par le biais d’une reconstruction tridimensionnelle enrichie de l’objet à évaluer. En particulier, nous avons employé simultanément un système stéréoscopique de vision et un système à projection de lumière structurée afin de reconstruire les contours et les surfaces de différents objets 3DProducing industrially manufactured parts generates a very large number of data of various types defining the manufacturing geometries as well as the quality of production. This PhD work has been carried out within the framework of the realization of a cognitive vision system dedicated to the 3D evaluation of manufactured objects including possibly free form surfaces, taking into account the geometric tolerances and uncertainties. This system allows the comprehensive control of manufactured parts, and provides the means for their automated 3D dimensional inspection. The implementation of a multi-sensor (passive and active) measuring system enabled to improve significantly the assessment quality through an enriched three-dimensional reconstruction of the object to be evaluated. Specifically, we made use simultaneously of a stereoscopic vision system and of a structured light based system in order to reconstruct the edges and surfaces of various 3D objects
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Alimi, Abib Olushola Yessou. "Imagerie tridimensionnelle en lumière polarisée : vers une analyse multi-échelle et multimodale avec l'imagerie par résonance magnétique pondérée en diffusion." Thesis, Université Côte d'Azur, 2020. http://www.theses.fr/2020COAZ4025.
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L’Imagerie par Résonance Magnétique pondérée en diffusion (IRMd) est la seule modalité in-vivo et non invasive offrant des informations sur la connectivité structurelle du cerveau humain. Cela est effectué via l’estimation de la distribution des orientations de fibres (FOD) de la matière blanche et leur suivi ou tractographie. Dans cette thèse, l’Imagerie tridimensionnelle en Lumière Polarisée (3D-PLI) est, grâce à sa haute résolution, considérée comme une potentielle technique complémentaire et de validation de l’estimation et du suivi des orientations de fibres par l’IRMd. Ainsi, notre travail a pour but principal de combler l’écart de résolution et d’étudier des critères de comparaison quantitative entre l’IRMd et la 3D-PLI pour ainsi ouvrir la voie à une analyse multi-modale et multi-échelle.Nos contributions sont multiples. D’abord, nous étudions l’orientation des fibres produites par 3D-PLI et proposons une méthode pour lever l’ambiguıẗ é du signe de l’inclinaison pour une estimation plus précise. Puis, nous développons une méthode analytique de calcul de la FOD des mesures microscopiques de 3D-PLI à la résolution meso- ou macroscopique de l’IRMd. Ensuite, à partir des données PLI du cerveau, nous effectuons la tractographie à diverses échelles et montrons la conservation de l’architecture structurelle des fibres malgré la baisse de résolution. Enfin, nous nous intéressons à la théorie de l’homologie en vue d’évaluation quantitative des résultats de tractographie. En somme, nous développons des méthodes en IRMd et 3D-PLI, et les validons sur des données synthétiques et réelles tout en établissant les bases d’études multi-échelles et multi-modales entre IRMd et 3D-PLIDiffusion Magnetic Resonance Imaging (dMRI) is the only non-invasive and invivo imaging modality able to provide human brain structural connectivity information. This is done via an estimation of the fiber orientation distribution (FOD) of white matter and dMRI tractography. In this thesis, three-dimensional Polarized Light Imaging (3D-PLI) is investigated and, thanks to its high spatial resolution, is presented as a complementary and potential technique for validation and guidance of dMRI fiber orientation estimates and tracking. The main goal of this work is, thus, to propose a strategy to close the resolution gap between dMRI and 3D-PLI and to investigate metrics for their quantitative comparison and, henceforth, to pave the way for multiscale and multimodal image analysis.Contributions in this thesis are manifold. First, we study the 3D-PLI fiber orientation and propose a method to disentangle the sign ambiguity of its inclination angle for an accurate determination of the 3D orientation. Second, we introduce an analytical and fast technique to compute the FOD from microscopic 3D-PLI orientation estimates to the meso- or macroscopic dimensions of dMRI. Third, we perform tractography at multiple scales from 3D-PLI human brain data to demonstrate the preservation of the fiber tracts architecture regardless of the decrease in resolution. Finally, we investigate how these obtained tractograms can be inspected using homology theory for a quantitative evaluation between them. Overall, we develop original and efficient dMRI and 3D-PLI methods, validate on both synthetic and human data and lay the foundations for multiscale and multimodal studies between dMRI and 3D-PLI
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Benmoussat, Mohammed Seghir. "Hyperspectral imagery algorithms for the processing of multimodal data : application for metal surface inspection in an industrial context by means of multispectral imagery, infrared thermography and stripe projection techniques." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4347/document.
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Le travail présenté dans cette thèse porte sur l'inspection de surfaces métalliques industrielles. Nous proposons de généraliser des méthodes de l'imagerie hyperspectrale à des données multimodales comme des images optiques multi-canales, et des images thermographiques multi-temporelles. Dans la première application, les cubes de données sont construits à partir d'images multi-composantes pour détecter des défauts de surface. Les meilleures performances sont obtenues avec les éclairages multi-longueurs d'ondes dans le visible et le proche IR, et la détection du défaut en utilisant l'angle spectral, avec le spectre moyen comme référence. La deuxième application concerne l'utilisation de l'imagerie thermique pour l'inspection de pièces métalliques nucléaires afin de détecter des défauts de surface et sub-surface. Une approche 1D est proposée, basée sur l'utilisation du kurtosis pour sélectionner la composante principale parmi les premières obtenues après réduction des données avec l’ACP. La méthode proposée donne de bonnes performances avec des données non-bruitées et homogènes, cependant la SVD avec les algorithmes de détection d'anomalies est très robuste aux perturbations. Finalement, une approche, basée sur les techniques d'analyse de franges et la lumière structurée est présentée, dans le but d'inspecter des surfaces métalliques à forme libre. Après avoir déterminé les paramètres décrivant les modèles de franges sinusoïdaux, l'approche proposée consiste à projeter une liste de motifs déphasés et à calculer l'image de phase des motifs enregistrés. La localisation des défauts est basée sur la détection et l'analyse des franges dans les images de phaseThe work presented in this thesis deals with the quality control and inspection of industrial metallic surfaces. The purpose is the generalization and application of hyperspectral imagery methods for multimodal data such as multi-channel optical images and multi-temporal thermographic images. In the first application, data cubes are built from multi-component images to detect surface defects within flat metallic parts. The best performances are obtained with multi-wavelength illuminations in the visible and near infrared ranges, and detection using spectral angle mapper with mean spectrum as a reference. The second application turns on the use of thermography imaging for the inspection of nuclear metal components to detect surface and subsurface defects. A 1D approach is proposed based on using the kurtosis to select 1 principal component (PC) from the first PCs obtained after reducing the original data cube with the principal component analysis (PCA) algorithm. The proposed PCA-1PC method gives good performances with non-noisy and homogeneous data, and SVD with anomaly detection algorithms gives the most consistent results and is quite robust to perturbations such as inhomogeneous background. Finally, an approach based on fringe analysis and structured light techniques in case of deflectometric recordings is presented for the inspection of free-form metal surfaces. After determining the parameters describing the sinusoidal stripe patterns, the proposed approach consists in projecting a list of phase-shifted patterns and calculating the corresponding phase-images. Defect location is based on detecting and analyzing the stripes within the phase-images
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Mayer, Jürgen 1977. "Mesoscopic 3D Quantitative Imaging: Attenuation Correction with OPTiSPIM." Doctoral thesis, Universitat Pompeu Fabra, 2015. http://hdl.handle.net/10803/523519.
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This thesis covers a number of technical developments, to improve mesoscopic imaging and analysis, with a focus on quantitative imaging. The main topic is attenuation in light sheet fluorescence microscopies (LSFM). Attenuation can be a prominent part of signal deterioration, however none of the presented technical improvements in LSFM address this problem directly.
We address the problem by fusing optical projection tomography (OPT) with selective plane illumination microscopy (SPIM) in a hybrid setup (OPTiSPIM). In contrast to SPIM, that relys on fluorescent contrast, OPT can reconstruct data from absorbing contrast.
Apart from having registered multimodal datasets by fusing data from different contrast mechanisms, the reconstructed absorption contrast provides a 3D attenuation map to the sample. This map is not accessible with a single SPIM scan, but allows for correcting the deterioration of the fluorescent SPIM signal. The corrected signal provides a more accurate measure of fluorescence in the sample.Aquesta tesi cobreix una sèrie de desenvolupaments tècnics, per a millorar l’adquisició i l’anàlisi d’imatges mesoscòpiques, centrant-se en l’obtenció quantitativa d’imatges. El tema principal és l’atenuació en microscòpia de làmina de llum fluorescent (LSFM). L’atenuació pot ser una causa important en el deteriorament de la senyal, tot i que cap de les millores tècniques existents en LSFM anaven adreçades a aquest problema directament. Hem abordat aquest problema mitjançant la fusió de la tomografia de projecció òptica (OPT) amb la microscòpia de pla d’il.luminació selectiva (SPIM) en un únic aparell híbrid (OPTiSPIM). A diferència de l’SPIM, que es basa en contrast de fluorescència, l’OPT permet recontruir dades del contrast d’absorbància. A part d’haver registrat dades multimodals mitjançant la fusió de dades de diferents mecanismes de contrast, el contrast d’absorció reconstruït obté un mapa d’atenuació en 3D de la mostra que permet la correcció del deteriorament de la senyal fluorescent obtinguda amb l’SPIM. Aquesta senyal corregida permet una mesura més acurada de la fluorescència de la mostra.
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Schmittberger, Bonnie Lee. "Multimode Atomic Pattern Formation via Enhanced Light-atom Interactions." Diss., 2016. http://hdl.handle.net/10161/12108.
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The nonlinear interaction between light and atoms is an extensive field of study with a broad range of applications in quantum information science and condensed matter physics. Nonlinear optical phenomena occurring in cold atoms are particularly interesting because such slowly moving atoms can spatially organize into density gratings, which allows for studies involving optical interactions with structured materials. In this thesis, I describe a novel nonlinear optical effect that arises when cold atoms spatially bunch in an optical lattice. I show that employing this spatial atomic bunching provides access to a unique physical regime with reduced thresholds for nonlinear optical processes and enhanced material properties. Using this method, I observe the nonlinear optical phenomenon of transverse optical pattern formation at record-low powers. These transverse optical patterns are generated by a wave- mixing process that is mediated by the cold atomic vapor. The optical patterns are highly multimode and induce rich non-equilibrium atomic dynamics. In particular, I find that there exists a synergistic interplay between the generated optical pat- terns and the atoms, wherein the scattered fields help the atoms to self-organize into new, multimode structures that are not externally imposed on the atomic sample. These self-organized structures in turn enhance the power in the optical patterns. I provide the first detailed investigation of the motional dynamics of atoms that have self-organized in a multimode geometry. I also show that the transverse optical patterns induce Sisyphus cooling in all three spatial dimensions, which is the first observation of spontaneous three-dimensional cooling. My experiment represents a unique means by which to study nonlinear optics and non-equilibrium dynamics at ultra-low required powers.
Dissertation
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Liu, Hsin-You, and 劉信佑. "Multimode Emission of White Organic Light Emitting Diodes with Resonant Cavity structure." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/32322633021884799506.
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碩士國立成功大學
光電科學與工程研究所
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In this study, we evaporate distributed bragg reflectors (DBR) using e-beam evaporator system, then we fabricate organic light emitting diodes (OLED) on DBR. Our resonant cavity OLED exhibit multimode emission, and spectral narrowing, enhancement of emitting intensity were observed due to the resonant effect. Finally, we measure the characteristic of the devices. In this study, we design suitable DBR reflector, and control the optical length of resonant cavity carefully. We add SiO2 filler layer to increase optical length, and make the resonant cavity device emit a white color consisting of multimode emission. The yield-current density(Y-J) characteristics of the four modes device showed the yield of 5.85cd/A at operation current density of 200A/m2 and its CIE also showed (x=0.33, y=0.32) at 8Volt with better performance in color-rendering index (CRI) of 82.17. The current efficiency was enhanced by 29% compared with conventional organic light emitting diodes(4.53cd/A) by the resonant effect. Our results clearly imply that by the reasonable design of the resonant cavity structure, it is possible to realize multimode emission of white organic light emitting diodes with even higher efficiency and better CRI.
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Pinho, Cátia Manuela Rodrigues. "Optimized photonic integrated solutions for next generation optical systems." Doctoral thesis, 2019. http://hdl.handle.net/10773/29187.
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Next generation optical systems can highly benefit from optimized photonic integrated solutions. Photonic integrated circuits (PIC) appear as a promising technology under the current demand for flexibility/reconfigurability in optical systems and telecommunications networks. PIC-based optical systems offer an efficient and cost-effective solution to data transmission increasing claims. In order to contribute to the development of integrated photonic technology, optimized PIC solutions addressing different steps of the PIC development chain, mainly design, testing, and packaging processes, are investigated.
Optical signal data compression techniques are progressing to sustain the fast processing/storing of large amounts of bandwidth demanding data, with the advantage of resorting to photonic integrated solutions for the implementation of optical transforms, e.g., Haar transform (HT). This demand motivated the research of an optimized PIC design solution in silicon nitride (Si3N4) based platform comprising a two-level HT network for compression, and a switching network as a framework that supplies all logical inputs of the HT network for testing/characterization purposes. Optimized design models for the multimode interference key building block structure of the PIC design solution, are proposed. Additionally, a first test and characterization of PIC solutions implementing the HT for compression applications in indium phosphide (InP) based platform and in a new organic-inorganic hybrid material were realized. Taking advantage of a tunable lattice filter dispersion compensator in Si3N4-based integrated platform, it was demonstrated a real-time extended reach PAM-4 transmission over 40 km enabled by the photonic integrated dispersion compensator, with application in data center interconnects. Under photonic integrated high-Q resonators need for accurate performance measurement, a technique based on RF calibrated Mach-Zehnder interferometer, and Brillouin gain measurements through Lorentzian fitting analysis were successfully attained.
Finally, as technical and functional requirements of PIC demand a thorough characterization/testing to provide an accurate prediction of its performance, and current testing platforms can be expensive and have low flexibility, a proof of concept of a new soft-packaging flexible platform for photonic integrated processors and spatial division multiplexing systems, based in spatial light modulation operation principle is proposed.Os sistemas óticos de nova geração beneficiam com a otimização de fotónica integrada. Com os circuitos de fotónica integrada (PIC) avançados a surgir como uma tecnologia promissora, dentro da crescente procura por flexibilidade/ reconfigurabilidade dos sistemas óticos e redes de telecomunicações. Os sistemas óticos baseados em PIC oferecem soluções eficientes e rentáveis em resposta às necessidades crescentes de transmissão de dados. De modo a contribuir para o desenvolvimento tecnológico associado à fotónica integrada, são investigados no âmbito desta dissertação diferentes soluções otimizadas de PIC, abordando diferentes estágios do seu desenvolvimento, nomeadamente projeto/design, teste e encapsulamento. Técnicas de compressão de sinais óticos estão a progredir no sentido de apoiar a expansão de velocidade de processamento e quantidade de armazenamento com elevada largura de banda associada. São esperadas vantagens recorrendo a PIC para a implementação de transformadas óticas, e.g., transformada de Haar (HT). Esta necessidade motivou a investigação de soluções de PIC com design otimizado, desenvolvidas em plataforma integrada de nitreto de silício (Si3N4). O PIC desenhado é constituído por uma rede 2D a executar a HT para fins de compressão e uma rede de comutação para produzir todas as entradas lógicas esperadas para teste e caracterização. São propostos modelos de design otimizados para a estrutura elementar que compõe o PIC, i.e., componente de interferência multimodal. Adicionalmente, foi realizado o primeiro teste e caracterização experimental de um PIC implementando a HT para fins de compressão, numa plataforma integrada de fosfato de índio (InP) e num material orgânico-inorgânico híbrido. Tirando partido de um filtro sintonizável para compensação de dispersão, desenvolvido em plataforma integrada de Si3N4, foi demostrado um link de transmissão alargada (40 km) em modulação PAM-4, com possível aplicação em centros de processamento de dados de interconexão. A necessidade de medições precisas de desempenho para a caracterização efetiva de soluções integradas de ressoadores de elevado fator de qualidade, motivou a implementação de uma técnica de medição eficaz. Esta é baseada num interferómetro de Mach-Zehnder calibrado em rádio frequência e na realização de mediações de ganho de Brillouin por análise Lorentziana de ajuste de curva. Por fim, tendo em conta os rigorosos requisitos técnicos e funcionais associados ao teste/caracterização precisa de PIC e o facto de as atuais soluções serem dispendiosas e pouco flexíveis. Uma prova de conceito de uma nova plataforma flexível de encapsulamento por software é proposta com aplicação em processadores PIC e sistemas com multiplexagem por divisão espacial.
Programa Doutoral em Telecomunicações
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Chistè, Elena. "Light emitting functionalized porous silicon microparticles as multimodal system in theranostics." Doctoral thesis, 2020. http://hdl.handle.net/11562/1012726.
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Porous silicon (pSi) is a sponge-like material obtained by anodic porosification of a crystalline silicon wafer in HF; pSi microparticles can be obtained by sonication of the porous layer. This material is characterized by exclusive intrinsic properties that make it suitable for theranostics (i.e. the combination of therapy and diagnostic) with a faster and more specific response to the disease for each patient (i.e. per-sonalized medicine). Due to a quantum confinement effect, this material was found to be photoluminescent at room temperature, allowing its traceability by op-tical imaging in-vitro and in-vivo. The electrochemical etching produces a material with a high surface to volume ratio, making pSi very attractive as a carrier, in per-spective of drug loading and release. Furthermore, the ability to functionalize the surface is essential for the conjugation with other agents (molecules, dyes, magnet-ic nanoparticles, among all) and for further applications (contrast agent in magnet-ic resonance imaging and for photothermal and photodynamic therapy). Optical properties and porosity, together with the biodegradability, the biocompat-ibility and the absence of immunogenicity are the major characteristics to exploit porous silicon microparticles as a multifunctional system in theranostics. Some of its limitations are related to (i) the broad size distribution, due to the top-down fabrication approach, and (ii) its degradation in aqueous media that causes a pho-toluminescence quenching. One of the aims of this PhD thesis work was to overcome these limiting issues in an original and effective approach: (i) an ultrasonic post-functionalization treat-ment and (ii) an inorganic coating based on TiO2 deposition have been experimen-tally validated, respectively. Once fabrication and functionalization protocols are well addressed (first objec-tive of this experimental work), pSi has several potentialities to be improved, for example, combining further diagnostic or therapeutic functionality. Along this di-rection, the second objective of this thesis work, the more applicative one, was the study about adding magnetic properties to this material by infiltrating and attach-ing magnetic nanoparticles inside its pores. As a fundamental step for the reliabil-ity in theranostics, the interaction with human immune cells is explored to evaluate the internalization mechanism, the biocompatibility and the immunogenicity of this system. To complete the trajectory towards theranostics, preliminary results about the employment of pSi microparticles as immune adjuvant delivery are pre-sented, in the perspective of immunotherapy. It is possible, that the presentation of these molecules carried by the microparticles could lead to enhanced cell activa-tion, with respect to the presentation of the soluble molecule.
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Plöchl, Michael. "Cognition in the Light of Perceptual and Behavioral Context." Doctoral thesis, 2015. https://repositorium.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-2015072313364.
Full textAbstract:
The cognitive processing of a stimulus does not only depend on the physical properties of the stimulus itself but also on the larger context in which it occurs. In this thesis I will present a number of studies that investigate this context-dependency at different levels of cognition. In particular these levels include (1) sensory processing within a modality, (2) sensory integration across modalities and (3) the relation between sensory perception and motor behavior. Accordingly the chapters in this thesis are partitioned into three larger parts, each of which relates to one of these levels.
The first study in Part 1 investigates the role of neural oscillations during perceptual grouping. By measuring EEG during contour integration we were not only able to identify the neural sources involved in this process but also to demonstrate local and long-range synchronization of oscillatory activity within frontoparietal networks. This study is then followed by a more general discussion about the properties of oscillatory activity and how they might relate to event-related potentials.
The focus of Part 2 will then be on cross-modal interactions and their possible utilization for real-life applications. First we show that simultaneously presented auditory and tactile cues lead to interactions on both a behavioral and neural level. Subsequently we demonstrate how the observed perceptual effects can be used to optimize auditory and tactile localization performance. Finally we propose a setup for utilizing tactile information to enhance the perceptual interpretation of 360° visual scenes.
The third and last part of this thesis is dedicated to problems and applications of measuring EEG in the presence of eye movements. Therefore we use eye tracking to investigate and characterize EEG artifacts resulting from ocular activity. Subsequently we develop an algorithm that allows objectively and reliably identifying these artifacts and removing them from the data without affecting the signal from neural sources. Employing this algorithm we then demonstrate that combined EEG and eye tracking can be used for monitoring and shaping both the gaze behavior and the related brain activity in ASD patients.
Next to studying cognition with regard to perceptual and behavioral context, this thesis also focuses on the question how the context-relevant signal components can be identified and extracted from the EEG. In the studies presented here we applied a variety of different strategies to approach this problem. These range from resorting to prior knowledge and analyzing only activity from predetermined cortical sources on the one hand, to purely data driven approaches based on logistic regression or eye tracking information on the other hand.
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Schröder-Schetelig, Johannes. "Multimodal high-resolution mapping of contracting intact Langendorff-perfused hearts." Doctoral thesis, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-1551-8.
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