Tesis sobre el tema "Guides à modes lents"
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Mahapatra, Sukanya. "Developing slow-mode nanophotonic platform for strong interaction between cold Rb atoms and guided photons". Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASP022.
Texto completoThis thesis presents the results of my PhD research on the design, fabrication, and first optical characterisation of GaInP-based slow-mode nanophotonic waveguides intended for the strong interaction of guided photons with the D₂ transition (780 nm) of ⁸⁷Rb atoms. The approach involves coupling atoms to the guided mode of a waveguide, a concept referred to as Waveguide Quantum Electrodynamics (Waveguide QED). The photonic crystal waveguides were designed with dispersion engineering to achieve slow mode with high group indices (∼30 - 50) around 780 nm. In the design, fabrication tolerance has been addressed by ensuring guided mode over a bandwidth of ∼10 nm. The waveguide is intended to be suspended, allowing free space around its vicinity to facilitate the convenient transport of atoms to its proximity and easy coupling of light from an external laser source. Details on an optimized and reproducible nanofabrication process have been reported. The encountered fabrication challenges and the corresponding solutions have been addressed, followed by an analysis of the fabrication results. A preliminary optical characterisation of the waveguides was conducted, in which the transmission spectra featuring the guided mode around 780nm were observed
Zang, Xiaorun. "Lumière lente dans les guides à cristaux photoniques pour l'interaction renforcée avec la matière". Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0172/document.
Texto completoIn this thesis, we firstly investigated the striking influence of random disorder on light transport near band edges in one dimensional photonic crystal wave guides, i.e. light localization. Near-field measurements, statistical simulations and theoretical model revealed the existence of a lower bound for the spatial extent of localized modes. We also showed that the disorder level and the spatial extent of individual localized mode is linked by the photon effective mass rather than the generally considered group velocity. Secondly, hybrid cold atoms and photonic crystal wave guides system have been recognized as a promising paradigm for engineering large light-matter interaction at single atoms and photons level. In this thesis, we studied the basic physics, i.e. light transport in periodic nanophotonic wave guides coupled to two-level atoms. Our developed general semi-analytical expression can quickly characterize the coupling between cold atoms and guided photons. Aim to overcome the significant technical challenges existed for developing hybrid atom-photonic systems, we designed a nanophotonic waveguide, which supports a slow guided Bloch mode with large evanescent tail in free space for cold atoms trapping (release the limitation imposed by Casmir Polder force and technical challenge of nanoscale manipulation of cold atoms). To match precisely the slow light region of the guided mode to the atomic transition line, we carefully engineered the photonic band and the dispersion curve (i.e.flatness) of the guided mode so that the interaction strength is robust against unpredictable fabrication imperfection
Latry, Olivier. "Théorie des modes locaux dans les guides perturbés application : couplage fibre optique - photodiode PIN". Rouen, 1995. http://www.theses.fr/1995ROUE5001.
Texto completoFerrier, Lydie. "Micro-nano structures à base de cristaux photoniques pour le contrôle 3D de la lumière". Phd thesis, Ecole Centrale de Lyon, 2008. http://tel.archives-ouvertes.fr/tel-00625602.
Texto completoFaggiani, Rémi. "Resonant nanophotonics : structural slow light and slow plasmons". Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0396/document.
Texto completoEnhancing light-matter interactions at micro and nanoscales is one of the spearheads of nanophotonics. Indeed, the control of the field distribution due to the resonant interaction of nanostructures with electromagnetic waves has prompted the development of numerous optical components for many applications in telecommunication, spectroscopy or sensing. A promising approach lies in the control of light speed in nanostructures. Light slowdown, obtained by wave interferences in periodic structures or subwavelength confinement in plasmonic waveguides, is associated to pulse compressions and large field enhancements,which are envisioned as key processes for the miniaturization of optical devices and the enhancement of light-matter interactions.The thesis studies both fundamental aspects and possible applications related to slow light in photonic and plasmonic nanostructures. In particular, we study the impact of periodic system sizes on the group velocity reduction and propose a novelfamily of resonators that implement slow light on very small spatial scales. We then investigate the role of fabrication disorder in slow periodic waveguides on light localization and demonstrate how modal properties influence the confinement of localized modes. Also we propose a new hollow-core photonic crystal waveguide that provides efficient and remote couplings between the waveguide and atoms thatare trapped away from it. Finally we demonstrate the important role played by slow plasmons on the emission of quantum emitters placed in nanogap plasmonic antennas and explain how large radiation efficiency can be achieved by overcoming quenching in the metal. Additionally, one part of the thesis is devoted to thederivation of a novel modal method to accurately describe the dynamics of plasmonic resonators under short pulse illumination
Gerelli, Emmanuel. "Nanopinces optiques à base de modes de Bloch lents en cavité". Phd thesis, INSA de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00838792.
Texto completoKnoesen, André. "Guided modes in anisotropic dielectric planar waveguides". Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/14898.
Texto completoPerségol, Dominique. "Réalisation d'un modulateur électrooptique utilisant l'excitation résonnante des modes guides". Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37617533m.
Texto completoECKERLE, MICHAEL. "Couplage des modes dans les guides d'ondes optiques multimodes et applications". Université Louis Pasteur (Strasbourg) (1971-2008), 1994. http://www.theses.fr/1994STR13189.
Texto completoBonnet, Anne-Sophie. "Analyse mathematique de la propagation de modes guides dans les fibres optiques". Paris 6, 1988. http://www.theses.fr/1988PA066093.
Texto completoCHEN, SHUFEN. "Modes hybrides dans des guides realises par echange protonique sur linbo#3". Nice, 1992. http://www.theses.fr/1992NICE4595.
Texto completoLe, Pennec François. "Structures alternatives de filtres passe-bande microondes combinant résonateurs diélectriques et modes évanescents". Brest, 1991. http://www.theses.fr/1991BRES2021.
Texto completoDjellouli, Rabïa. "Contributions à l'analyse mathématique et au calcul des modes guides des fibres optiques". Paris 11, 1988. http://www.theses.fr/1988PA112139.
Texto completoThis work deals with the mathematical and numerical analysis of propagation characteristics of guided modes of several dielectric structures: Optical fibers, half couplers and optical couplers. From the mathematical view-point we first study a scalar equation which modelize the propagation under the assumptions of weak guidance. Then we analyse the complete system of the Maxwell equations. These studies are based on the spectral theory of self-adjoint operators. We etablish , by the Max-Min principle, the dispersion relation between the frequency and the propagation constant. Then we give a detailed description of the dispersion curves: framing, dependance with respect to the index profile, asymptotic behaviour, cut-off. . . From the numerical point of view, we propose an original method, based on integral representation, to calculate the propagation constants and the cut-off frequencies of guided modes of step-index profile fibers with arbitrarily shaped cross sections. The case of an optical couplers is also treated by this method with an appropriate adaptation. We end this work by making various numerical simulations in order to validate our approximation method. The conclusion is that our method is well adapted to the computation of the optical structures presented above: good accuracy and reasonnable cost
Djellouli, Rabïa. "Contribution à l'analyse mathématique et au calcul des modes guides des fibres optiques". Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37613278s.
Texto completoSalomon, Antoine. "Cristaux photoniques bidimensionnels en SOI et leur couplage avec un miroir de Bragg". Université Joseph Fourier (Grenoble), 2007. http://www.theses.fr/2007GRE10018.
Texto completoSimilar to eletronic crystals, photonic crystals are rnaterials whose dielectric is modulated. Just like in electronic,where the periodical variation of the potential structures the electrons' energies dispersion, this modulation of the optical index structures the photons' energies dispersion. It is then possible to control light by forbidding certain energies, band or space directions. Ln addition, because of their high integration and their compatibility with conventional C-MOS type technologies, Silicon On Insulator (SOI) photonics crystals possesses a strong potential for the development of future electro-photonic chips. Ln this context, the object of this thesis woks was the study of SOI photonic crystals light sources and especially the coupling between two dimensional photonic crystal light sources and a Bragg mirror. Ln a first part, this work focuses on the theoretical and technological aspects of photonic crystals. We describe the physical principles, especially the band structure, of photonic crystals in order to exhibit the way they operate and their properties. Then we present the technological fabrication as well as optical characterization tools. Ln a second part, we report on the coupling between radiatives desexcitations and photonic crystals' optical modes. We demonstrate that by coupling to slow group velocity modes or cavity modes, an optical source at 1. 1[Mu]m can be achieved. The results obtained are in agreements with calculated band diagrams. Finally we investigate the coupling between a Bragg mirror and a two dimensional photonic crystal. More precisely, we study the impact of the coupling distance on light extraction and the quality factor (Q). We show that these two quantities are periodical functions of [Lambda]/2 of it. We also exhibit that, according to the coupling distance, it is possible to enhance light extraction and the Q, compared to the characteristics of the single crystal. At last we present the first realization of a device coupling a two dimensional photonic crystal and two Bragg mirrors
Wilson, Daniel W. "Optical waveguiding in photorefractive crystals : photoinduced polarization conversion and electron waveguiding in semiconductor nanostructures : modes, directional coupling, and discontinuities". Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/14934.
Texto completoRATAJCZAK, PHILIPPE. "Applications du formalisme rigoureux des equations integrales a l'etude de structures 3d inhomogenes excitees par modes guides". Nice, 1995. http://www.theses.fr/1995NICE4830.
Texto completoLomer, Barboza Mauro. "Contribution à l'étude des modes de galerie optiques : Fabrication de guides optiques non linéaires par diffusion de plomb". Limoges, 1992. http://www.theses.fr/1992LIMO0162.
Texto completoGanier, Franck. "Le traitement cognitif : déterminant de la conception de documents procéduraux : le cas des guides d'utilisation SEB". Dijon, 1999. http://www.theses.fr/1999DIJOL003.
Texto completoThe aim of the work reported here was to transfer knowledge acquired in the field of psycholinguistics to the domain of technical writing and, in particular, to that of writing instructions. Several studies carried out in natural situations and in laboratory suggested theorical research and applications. A preliminary observation allowed to apprehend users'behaviors when dealing with procedural documents. Furthermore, three studies were carried out to investigate the effects of different instructional formats on how users processed instructional documents. In the first experiment, seven formats of instructions were tested with two groups of adults at two levels of education (high vs. Low levels of schooling). The second experiment assessed the effects of an advanced organizer on the elaboration of a representation and a control activities during the execution of instructions. The third experiment explored users' representations induced by processing textual or graphic instructions. These investigations allowed to developp a procedural model of processing instructions aimed at helping technical writers to design procedural documents. This "user-model" helped to improve markedly the quality of documents, facilitated searching, and lead to a greater understanding of the instructions
Petitjean, Michae͏̈l. "Etude de microrésonateurs optiques par modes de galerie couplés à des fibres polies sur le côté". Limoges, 2000. http://www.theses.fr/2000LIMO0006.
Texto completoKulatunga, Ushiri Kumarihamy. "Argumentation as a Lens to Examine Student Discourse in Peer-Led Guided Inquiry for College General Chemistry". Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4712.
Texto completoCourtois, Loys. "Détermination de modes électromagnétiques de guides d'ondes corrugués surdimensionnés sur l'installation de chauffage des électrons du Tokamak Tore Supra". Grenoble INPG, 2001. http://www.theses.fr/2001INPG0013.
Texto completoGacemi, 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.
Texto completoFocusing 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
Hamitouche, Zahia. "Études expérimentales et numériques de la propagation dans des guides d'onde à section linéairement variable". Le Havre, 2008. http://www.theses.fr/2008LEHA0003.
Texto completoThe aim of this work is to provide the experimental and numerical results on the behaviour of a Lamb wave in duraluminium elastic waveguides. These waveguides include an area of linearly varying section, located between two areas of constant thickness of 2 mm and 5 mm. These waveguides are only differing by the slope of their varying section domain. Several phenomena were observed : the adiabaticity of the Lamb modes in the area of varying section, the reflexion of an incident Lamb mode when it reaches its thickness cut-off in the varying section area and its transmission outside this zone by tunnel effect. The experimental and numerical results obtained show the existence of adiabatic waves in all the studied guides. In particular, the amplitude of normal displacements of the adiabatic S0 mode on the plane surface varies according to the thickness and shows a number of resonances located in this zone. The number and the positions of resonances are strongly depending of the varying section slope. If the same mode is propagated towards the decreasing thicknesses in a waveguide of strong slope, a transmission of this incident wave is observed at the end of the varying section domain into other modes. When the Lamb modes having cut-off are propagated towards the decreasing thicknesses, a reflexion at their thickness cut-off is observed. Nevertheless, a small part of their energy is transmitted by tunnel effect into other Lamb modes in the thinner part of the waveguide. The energy of the transmitted modes have been measured and represents a maximum of 2% of the energy of the incident mode. In addition, the varying section area shows a phenomenon of frequency filtering for the Lamb modes having cut-off. The experimental results are in good agreement with the numerical results. The numerical study allowed the obtention of a reliable predictive model and helped to highlight the physical meaning of the observed phenomenon
Lecouvé, Marc. "Conception et réalisations de filtres microondes à modes évanescents à l'aide d'un algorithme génétique : Egalisation d'amplitude par l'algorithme de levenberg-Marquardt". Bordeaux 1, 2000. http://www.theses.fr/2000BOR12211.
Texto completoChane-Kee-Sheung, Harry. "Etude d'un réseau de fentes longitudinales en guides d'ondes rectangulaires en modes de diffraction et de rayonnement : détermination de sa surface équivalente radar". Toulouse 3, 1993. http://www.theses.fr/1993TOU30116.
Texto completoGallezot, Matthieu. "Simulation numérique du contrôle non-destructif des guides d’ondes enfouis". Thesis, Ecole centrale de Nantes, 2018. http://www.theses.fr/2018ECDN0040/document.
Texto completoVarious elements of civil engineering structures are elongated and partially embedded in a solid medium. Guided waves can be used for the nondestructive evaluation (NDE) of such elements. The latteris therefore considered as an open waveguide, in which most of waves are attenuated by leakage losses into the surrounding medium. Furthermore, the problem is difficult to solve numerically because of its unboundedness. In aprevious thesis, it has been shown that the semi-analytical finite-element method (SAFE) and perfectly matched layers(PML) can be coupled for the numerical computation of modes. It yields three types of modes: trapped modes,leaky modes and PML modes. Only trapped and leaky modes are useful for the post-processing of dispersion curves. PML modes are non-intrinsic to the physics. The major aim of this thesis is to obtain the propagated and diffracted fields, based on modal superpositions on the numerical modes. First, we show that the three types of modes belong to the modal basis. To guarantee the uniqueness of the solutions an orthogonality relationship is derived on the section including the PML. The forced response can then be obtained very efficiently with a modal expansion at any point of the waveguide. Modal expansions are also used to build transparent boundaries at the cross-sections of a small finite-element domain enclosing a defect, thereby yielding the diffracted field. Throughout this work, we study whether solutions can be obtained with modal expansions on leaky modes only, which enables to reduce the computational cost. Besides, solutions are obtained at high frequencies (which are of interest for NDE) and in tridimensional waveguides, which demonstrates the generality of the methods. The second objective of this thesis is to propose an imaging method to locate defects. The topological imaging method is applied to a waveguide configuration. The general theoretical framework is recalled, based on constrained optimization theory. The image can be quickly computed thanks to the modal formalism. The case of a damaged waveguide is then simulated to assess the influence on image quality of the emitted field characteristics (monomodal, dispersive or multimodal)and of the measurement configuration
Pierre, Raphaël. "Propriétés effectives d'un cristal photonique. Extensions de la méthode des sources fictives. Application à l'étude du guidage de modes quasi-TEM uniformes". Phd thesis, Université Paul Cézanne - Aix-Marseille III, 2008. http://tel.archives-ouvertes.fr/tel-00360840.
Texto completoLe second volet est l'étude du guidage de modes quasi-TEM uniformes dans un guide métallique au moyen de parois structurées. Les structures sont des surfaces hard analysées grâce à la méthode modale tandis que les guides d'ondes associés le sont par une extension de la méthode des sources fictives. Cartes de champs et relations de dispersion révèlent le comportement des surfaces et guides envisagés.
Hamdad, Sarah. "Synthèse et étude de réseaux de nanoparticules métalliques pour l'exaltation de l'électroluminescence des OLEDs via l'effet plasmonique". Thesis, Paris 13, 2021. http://www.theses.fr/2021PA131056.
Texto completoIn this thesis work, we were interested in studying the improvement of the optical and electrical properties of OLEDs using square arrays of Ag nanoparticles. In particular, we focused on the study of surface lattice resonance (SLR) modes in order to understand the interaction mechanisms between the NPs in a grating. We have also studied the influence of these modes on the emission characteristics of an organic layer first under optical pumping and then under electrical pumping. For this, we have set up within the LPL laboratory several optical experiments and developed several numerical calculations in order to interpret the obtained results. These latter confirm the crucial role of Rayleigh anomalies in the appearance of directional emission. In the case of OLEDs, the studies carried out show that the presence of short period metallic structures can help to improve the electrical injection process of holes into the organic device. Besides, we show that the insertion of a longue period grating can improve the efficiency of the OLED. However, the existence of collective SLR modes is not guaranteed in this type of configuration and the emission directivity effects require further studies. The results obtained within the framework of this thesis work constitute an important step towards a deep understanding of the interactions between the grating of metallic NPs and the organic emitters and could open the way towards the study and the realization of superriadiant OLEDs, which would constitute an intermediate step to go to the organic laser diode
Félix, Simon. "Propagation acoustique dans les guides d'ondes courbes et Problème avec source dans un écoulement cisaillé". Phd thesis, Université du Maine, 2002. http://tel.archives-ouvertes.fr/tel-00007890.
Texto completoPour un guide courbe à deux ou trois dimensions, une formulation multimodale de la propagation acoustique est mise en place et validée, et des équations différentielles matricielles sont établies pour la pression et la vitesse longitudinale, ainsi qu'une équation de Riccati pour la matrice impédance. Si les caractéristiques du coude (section, admittance aux parois) sont constantes, un calcul algébrique de la matrice de diffusion est possible, qui permet l'étude des propriétés de diffusion de ce coude et de tout système complexe composé de conduits droits et courbes. Une comparaison de cette approche, ondulatoire, et d'une matrice de diffusion construite par la méthode des rayons montre une très grande similitude entre ces résultats à haute fréquence. L'atténuation dans un coude traité en parois par un matériau absorbant est enfin étudiée dans le cadre de l'approche multimodale et nous mettons en évidence plusieurs propriétés des conduits courbes traités.
La seconde partie de ces travaux concerne le problème de la propagation acoustique dans un guide droit siège d'un écoulement parallèle cisaillé, en présence d'une source. La fonction de Green de l'équation de Pridmore-Brown est calculée dans un premier temps. Par transformée de Fourier spatiale inverse, les pôles de la fonction de Green font apparaître les modes acoustiques perturbés par l'écoulement, dont il est alors possible de calculer l'amplitude. La présence d'un spectre continu dû à la singularité de l'équation de Pridmore-Brown est également mise en évidence, et la contribution du continuum de modes hydrodynamiques correspondant est étudiée et décrite.
Pelat, Adrien. "Approche modale de la propagation acoustique dans les guides d'ondes ouverts : application à l'acoustique urbaine". Phd thesis, Le Mans, 2009. http://cyberdoc.univ-lemans.fr/theses/2009/2009LEMA1014.pdf.
Texto completoIn urban areas, noise has become the main form of ''pollution'' recognized by the population. To address this major issue for society, much research has helped to describe the acoustic propagation in urban areas. However, as consequence of the high geometrical and physical complexity of urban areas, the energetic models implemented in usual predictive software limit the physical description of sound fields. It appears that fundamental work on acoustic propagation in complex environments must be pursued upstream from applications directly related to urban acoustics. In this context of upstream research, the essential idea of this work is to consider the street as an open waveguide. Indeed, the typical elongated shape promotes guided waves along the axis of the street. In contrast, the opening of this guide on an infinite domain - the sky - results in wave radiation leading to energy losses. The study of these competitive effects between guided waves and radiated waves is the key point of this work. To solve the wave equation in such an open three-dimensional guide, the principle of modal decomposition is used. In this approach, the wave field is a combination of a set of modes (called modal basis) whose contributions notably depend on end conditions at the guide extremities. The extension of the modal approach to the case of open waveguides need to introduce the concept of leaky modes. Through a preliminary study about two-dimensional closed guides with variable cross-section, the possibilities of the modal approach are apprehended in simple cases in order to be extended to the more complex case of three-dimensional open guides. Subsequently, a first work about leaky modes is done in the academic case of an open cylindrical guide with rectangular cross-section. In this work, the behavior and properties of leaky modes are studied in details when they are used in a modal approach. It is notably shown that only a small number of modes is necessary to accurately describe the field. Based on the findings of this first research, a coupled Modal-Finite Elements method, more suitable to the ''urban waveguide'' specificities is proposed. This work shows how, using PML (Perfectly Matched Layers), a new problem of propagation in closed guide may be substituted for the original problem of propagation in open guide. In this approach, several characteristics of the geometrical and physical complexity of urban areas can be taken into account. Illustrations based on the numerical implementation of the method reveal physical phenomena related to irregularities and absorption of facades, or the consideration of meteorological effects, and open both academic and applied research prospects
Guenneau, Sébastien. "Homogénéisation des quasi-cristaux et analyse des modes dans des fibres optiques de type cristal photonique". Aix-Marseille 1, 2001. https://hal.archives-ouvertes.fr/tel-01853818.
Texto completoRamos, Marie. "Etude du couplage entre une fibre optique unimodale et un guide d'onde en optique intégrée en vue de la réalisation d'un connecteur". Saint-Etienne, 1993. http://www.theses.fr/1993STET4025.
Texto completoRassem, Nadège. "Etude du guidage et du confinement de la lumière dans les guides optiques nanostructurés : application au filtrage spectral ultra-sélectif". Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0015.
Texto completoA CRIGF (Cavity Resonator Integrated Grating Filter) is a nanophotonic spectral filter with a narrow bandwidth (less than a nanometer) using a relatively focused beam. This structure, introduced recently (2010), is composed of a guided mode resonance grating filter (or resonant grating, or coupler grating) inserted between two Bragg gratings. Guided mode resonance gratings are known to exhibit very narrow peaks in their reflection spectrum (or transmission), due to the excitation of one guided mode of the structure via one diffraction order. This resonance phenomenon corresponds to an anomaly of Wood. But their major limitation remains their very low angular tolerance, and the CRIGF allows to overpass this problem.In literature, the numerical modeling of CRIGF was done only by FDTD with an important calculations time. We have used RCWA to model numerically the CRIGF by bringing a possibility of research of the eigen-modes. We have mainly shown thanks to calculations the extraordinary angular behavior of the CRIGF is very different from that of infinite gratings. We have proved thanks to the coupled modes theory extended to four modes that this large angular tolerance is due to an additional coupling that did not occur in infinite gratings.With an approach based on the Fabry-Perot cavity, we confirmed that the CRIGF behaves as a lossy Fabry-Perot cavity, which allowed us to define simple design rules such as the control of the spectral width and tuning the centering wavelength
Valier-Brasier, T. "Propagation acoustique en guides fluides et solides à parois rugueuses : formulation intégrale pour ondes de pression, de cisaillement et de Lamb". Phd thesis, Université du Maine, 2010. http://tel.archives-ouvertes.fr/tel-00534139.
Texto completoMathian, Marie. "Antennes large bande pour dispositifs micro-ondes de fortes puissances : mfp". Paris 11, 2007. http://www.theses.fr/2007PA112001.
Texto completoHerbin, Morgane. "Etude de l’influence de différents modes de synthèse sur la nature de la phase active de catalyseurs à base de molybdène : Caractérisation par couplage de spectroscopies XPS/LEIS/ToF-SIMS". Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10069/document.
Texto completoThe coupling of surface analysis techniques (XPS, LEIS et ToF-SIMS) allowed to characterize the nature of the active phase on Mo-based catalysts according to different modes of synthesis. To imitate chemical means by impregnation mode, model catalysts we prepared by spin-coating. In addition, a new physical path, by magnetron sputtering, has been explored for the synthesis of catalysts. Correlations between spectroscopic data XPS and LEIS on model systems determine the recovery rate and the structure of the active phase : Mo low content monomeric and high content polymeric entities. Finally, the catalytic performances of the different catalytic systems for the controlled oxidation of methanol are discussed under spectroscopic characterizations. This work has been performed within INTERREG IV CATARR network (Materia Nova, Mons University and Lille1 University)
Moutaouekkil, Mohammed. "Etude de la propagation des ondes élastiques de Lamb dans les matériaux composites micro/nano structurés : Application pour l’ingénierie des propriétés physiques des résonateurs électromécaniques". Thesis, Ecole centrale de Lille, 2018. http://www.theses.fr/2018ECLI0011/document.
Texto completoThe control of elastic wave propagation relies mainly on the design of artificial media based on structured materials to achieve advanced propagation dispersion engineering. During the thesis, the dispersion of the mode (S0) in micro-structured membranes based on AlN was numerically investigated and the resulting applications explored. The strong link between mode dispersion and sensitivity to external disturbances is highlighted by combining the AlN membrane with a layer of SiO2 structured into strips. In particular, it is shown that it is possible to obtain a TCF = 0 for the resonators without any degradation of the K2 coefficient. It is shown that it is possible to open wide band-gaps of 50% by structuring the AlN in the shape of strips or using pillars to form a PhnC. On this basis, designs of cavities and waveguides are proposed and their performances are studied according to the geometrical parameters. It is also proposed a new cavity design based on the introduction of a resonant defect with a disc shape in the PhnC and presenting very small size in comparison to the unit cell. The defect makes it possible to introduce quasi-flat modes in the band diagram and consequently allows the design of a new generation of phononic devices for signal processing and sensor applications. The optimal structures are used to design a magnetic field sensor design, a sensitivity of 5% is obtained for the localized mode in the case of defect based on magneto-elastic thin film
Roux, Jean-François. "Contribution à l'étude du coupleur a réseau non linéaire : génération de second harmonique dans des guides d'ondes organiques". Grenoble INPG, 1995. http://www.theses.fr/1995INPG0023.
Texto completoAchlan, Moustafa. "Surface Plasmon Polariton and Wave Guide Modes in a Six Layer Thin Film Stack". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS109.
Texto completoIn this thesis, we investigate the optical properties of a six-layer stack (air-Au-SiO₂-Au-Ti-glass). The interfaces are flat and the modeling is performed using elementary Fresnel expressions at the interface and plane wave propagation in the layers. Two models are used where the sample is: i) excited by a source at infinity (excitation by source at infinity (ESI)); ii) excited by a local source. In the experiments we are modeling this source consists of the inelastic tunneling electrons from a scanning tunneling microscope (STM). In our modeling this source is replaced by a vertical oscillating dipole. Using these two models one calculates the reflected (reflectance) and the transmitted (transmittance) flux from a source at infinity and the transmitted flux of a local source. Surface plasmon polariton (SPP) and wave guide (WG) modes may be identified in the reflectance, transmittance and transmitted flux. In a particular wavelength domain the SPP and WG repel each other giving rise to an avoided crossing. The choice of the gold (Au) and silica (SiO₂) thicknesses of the six-layer stack is guided by two requirements: high amplitude of the observable and wide wavelength dependence of the in-plane wave vector. We also study the influence of the gold and silica thicknesses on the observables. We find that the observables are significant for dAu[10, 90 nm] for the three and dAu[10, 50 nm] for six layer stacks and this predictive study guided the choice of the experimental sample thicknesses. The wave guide mode appears for dSiO₂ >190 nm. The electric field as a function of the penetration coordinate z is calculated in order to characterize the location of the field in the stack and to assign the nature of the modes. We observe that for the SPP the electric field is confined at the Au-air interface whereas, the electric fields corresponding to the WG mode are confined inside SiO₂ layer. Our calculations presented in this work are in good agreement with the experimental measurements performed in our group
Salas-Montiel, Rafael. "Sources lasers pulsées en optique intégrée sur verre". Grenoble INPG, 2008. http://www.theses.fr/2008INPG0024.
Texto completoThe development of integrated pulsed laser sources showing similar performances to those of bulk lasers represents a solution for applications in medicine, metrology and research where small size and robustness are required. Furthermore, the possibility to integrate both passive and active functions on the sa me substrate together with a high coupling efficiency with optical fibres makes these kinds of sources an attractive solution. This manuscript reports the study, realisation and characterisation of glass integrated optics hybrid passively Q-switched waveguide lasers. We have demonstrated the successful operation of a hybrid passively Q-switched waveguide laser. This laser is composed of a waveguide amplifier made of a Nd-doped phosphate glass combined with a saturable absorber cladding. The laser cavity was provided by two dielectric mirrors attached to the facets of the waveguides. An optical pulse width of 2. 0 :t 0. 1 ns was obtained for 180 :t 5 mW of launched pump power. The repetition rate ranges from 5 to 50 kHz for 110 to 260 :t 5 mW of launched pump power. The perspectives of this work could be the realisation of hybrid passively DFB Q-switched waveguide lasers and hybrid passively mode-Iocked waveguide lasers
Herbin, Morgane. "Etude de l’influence de différents modes de synthèse sur la nature de la phase active de catalyseurs à base de molybdène : Caractérisation par couplage de spectroscopies XPS/LEIS/ToF-SIMS". Electronic Thesis or Diss., Lille 1, 2014. http://www.theses.fr/2014LIL10069.
Texto completoThe coupling of surface analysis techniques (XPS, LEIS et ToF-SIMS) allowed to characterize the nature of the active phase on Mo-based catalysts according to different modes of synthesis. To imitate chemical means by impregnation mode, model catalysts we prepared by spin-coating. In addition, a new physical path, by magnetron sputtering, has been explored for the synthesis of catalysts. Correlations between spectroscopic data XPS and LEIS on model systems determine the recovery rate and the structure of the active phase : Mo low content monomeric and high content polymeric entities. Finally, the catalytic performances of the different catalytic systems for the controlled oxidation of methanol are discussed under spectroscopic characterizations. This work has been performed within INTERREG IV CATARR network (Materia Nova, Mons University and Lille1 University)
Velha, Philippe. "Ingénierie de mode en optique intégrée sur silicium sur isolant". Phd thesis, Université Paris Sud - Paris XI, 2008. http://tel.archives-ouvertes.fr/tel-00292092.
Texto completoPiantanida, Juan Pablo. "Théorie de l'information multi-utilisateur : information adjacente et connaissance imparfaite du canal". Paris 11, 2007. http://www.theses.fr/2007PA112053.
Texto completoThe capacity of single and multi-user channels under imperfect channel knowledge are investigated. We address these channel mismatch scenarios by introducing two novel notions of reliable communication under channel estimation errors, for which we provide an associated coding theorem and its corresponding converse. Basically, we exploit for our purpose an interesting feature of channel estimation through use of pilot symbols. This feature is the availability of the statistic characterizing the quality of channel estimates. We first introduce the notion of estimation-induced outage capacity, where the transmitter and the receiver strive to construct codes for ensuring reliable communication with a quality-of-service, no matter which degree of accuracy estimation arises during a transmission. Then the optimal decoder achieving this capacity is investigated. We derive a practical decoding metric and its achievable rates, for arbitrary memoryless channels that minimizes the average of the transmission error probability over all channel estimation errors. We next consider the effects of imperfect channel estimation at the receivers with imperfect (or without) channel knowledge at the transmitter on the capacity of state-dependent channels withe non-causal CSI at the transmitter (e. G. The multi-user Fading MIMO Broadcast Channel). We address this through the notion of reliable communication based on the average of the transmission error probability over all channel estimation erros. Finally, we consider several implementable DPC schemes for multi-user information embedding, through emphasizing their tight relationship with conventional multi-user information theory
Dubreuil, Nicolas. "Sources à diode laser auto-organisables - Nonlinearités dans des nanostructures semi-conductrices". Habilitation à diriger des recherches, Université Paris Sud - Paris XI, 2010. http://tel.archives-ouvertes.fr/tel-00561194.
Texto completoSciancalepore, Corrado. "Intégration hétérogène III-V sur silicium de microlasers à émission par la surface à base de cristaux photoniques". Phd thesis, Ecole Centrale de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00915280.
Texto completoMohamed, elarif Abderemane. "Évaluation et contrôle non destructifs des barreaux et plaques par génération acoustique induite par absorption de micro-ondes". Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14235/document.
Texto completoMany studies in the field of both nondestructive evaluation and testing of mechanical structures have been conducted so far by analyzing the contribution of the microwaves induce acoustic technique. This new non-contact technique can be easily adopted to generate acoustic waves in non-conducting materials. This work begins with studying the lateral vibrations generated within viscoelastic bars hold inside grooved electromagnetic waveguides and subjected to short microwave irradiations. A parametrical model is established in order to predict the shape of the temperature rise within the sample. Results emphasize the fact that these types of waveguides generate a sudden asymmetric temperature rise, which produces some flexural modes. Besides, the development of a 3D numerical model allow the prediction of new vibration modes which are related to the deformations of the bar cross-sections during the sudden thermal heating. Then, direct methods are developed to complete the assessment of the viscoelastic properties of bars placed inside conventional electromagnetic waveguides. Different analytical models are proposed to study the effects of the Poisson ratio either on the ratio between lateral and longitudinal vibrations or on the dispersion of longitudinal waves. An optimization algorithm that allows the Poisson ratio and the real part of the complex slowness evaluation by means of dispersion curves is elaborate before being applied in the specific case of two polymeric bars. Finally, analytical and numerical finite element methods are conducted to analyze the acoustic waves generated by a circular defect (hole) contained in a plate and heated locally by microwaves. Two acoustic approaches are performed to predict the temperature rise form. Furthermore, a nondestructive testing method is highlighted by a direct relationship between the size of the defect and the frequencies of some peaks that appear on the velocity spectra of the plate. This method could be applied to set up an inverse procedure that can be used to size these kinds of defects
Bourguignon-Mirebeau, Jennifer. "Préconditionnement de méthodes de décomposition de domaine pour les problèmes de diffraction d'ondes électromagnétiques impliquant une cavité profonde". Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00651957.
Texto completoBöhm, Julian. "Phénomènes de transport originaux dans des expériences micro-ondes via la mise en forme spatiale et spectrale". Thesis, Université Côte d'Azur (ComUE), 2016. http://www.theses.fr/2016AZUR4048/document.
Texto completoTransport of waves plays an important role in modern communication systems like Wi-Fi or optical fibres. Typical problems in such systems concern security against possible intruders, energy consumption, time efficiency and the possibility of mode filtering. Microwave experiments are suited to study this kind of problems, because they offer a good control of the experimental parameters. Thus we can implement the method of wave shaping to investigate atypical transport phenomena, which address the mentioned problems. Wave front shaping solely based on the transmission together with the Wigner-Smith time delay formalism allows me to establish special scattering states in situ. These scattering states avoid a pre-selected region, focus on a specific spot or follow trajectories of classical particles, so called particle-like scattering states. Mode filtering is induced inside a waveguide with wavy boundaries and position dependent loss. The boundary profiles are chosen in such a way that the two propagating modes describe an encircling of an exceptional point in the Bloch picture. The asymmetric mode filtering is found due to the appearing non-adiabatic transitions. Another part of my work deals with Grover’s quantum search. I put such a search into practice in a two-dimensional graphene-lattice using coupled resonators, which form a tight-binding analogue. In this proof of principle experiment we search for different resonators attached to the graphene-lattice. Furthermore, the scaling behaviour of the quantum search is quantified for a linear chain of resonators
Besley, James Austin. "Modes and solitons in waveguide optics". Phd thesis, 1998. http://hdl.handle.net/1885/144717.
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