Дисертації з теми "Optique à gradient d'indice"
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Lavanant, Enora. "Optiques infrarouge à gradient d'indice de réfraction en verres chalcogénures." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S127.
Thermal imaging is a growing field, thanks to the miniaturization and emergence of uncooled detectors of high quality and low cost. Research into new materials is also essential to bring new functionalities to IR systems. This thesis consisted in exploring methods of manufacturing a Gradient of Refractive INdex (GRIN) in chalcogenide glasses. These GRIN materials have a refractive index that varies according to the spatial position. Compared to traditional homogeneous optical elements, GRIN materials allow the optical designer to improve the performance of an imaging system or maintain performance and reduce the size, weight and/or number of lenses. Thus, it is possible to develop compact systems that have a high focusing power while correcting thermal, chromatic and spherical aberrations. While widely used in the visible, radial GRIN lenses are still elusive in the IR waveband. The first method of manufacture discussed in this manuscript is ion exchange. This process is very common in oxide glasses but is still under-exploited in chalcogenide glasses. The important mechanisms involved in the process are studied. The study focused on bath compositions, chalcogenide glass compositions (nature and content of mobile ions), immersion time and bath temperature. Controlled crystallization is the second method discussed. The difficulty lies in the choice of the glass composition. Indeed, the crystals generated during the crystallization of the glass must lead to a variation in the refractive index of the glass-ceramic compared to that of the base glass. Several compositions have been highlighted in order to apply the new process to spatially resolved crystallization. Using these two methods, chalcogenide glasses with axial and radial GRIN were obtained
Bardin, Fabrice. "Capteur à fibre optique à gradient d'indice inversé basé sur la résonance plasmon de surface : applications à la détection d'espèces chimiques." Phd thesis, Université Jean Monnet - Saint-Etienne, 2001. http://tel.archives-ouvertes.fr/tel-00001575.
Haj, Ibrahim Bicher. "Dépôt de couches minces à saut et à gradient d'indice par plasma en résonnance cyclotron." Phd thesis, Ecole Polytechnique X, 2007. http://pastel.archives-ouvertes.fr/pastel-00002930.
Froehly, Luc. "Nouveaux matériaux à gradient d'indice pour l'optique : étude des procédés de fabrication existants et développement de méthodes de caractèrisation." Saint-Etienne, 2000. http://www.theses.fr/2000STET4005.
Gaufillet, Fabian. "Cristaux photoniques à gradient : dispositifs et applications." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112295.
Artificially structured materials that are photonic crystals are commonly used for their dispersive properties. Their dielectric constant varies periodically across the wavelength in two or three directions with a sufficiently high index contrast. The resulting dispersion relation ω = ω(k) of the periodic variation has the form of a band structure within which there are photonic bandgaps in which the propagation of the electromagnetic field is prohibited. Outside of these bands, i.e. in the photonic band, there are the dispersion properties of the photonic crystals.The aim of this thesis is to design, fabricate and characterize graded photonic crystal devices. These devices were designed to be applied in areas ranging from microwaves to optics. We designed devices from photonic crystals with dispersive properties which make them similar to linear, homogeneous and isotropic media (LHI). In the unit cell of the LHI photonic crystal, we applied a gradient to achieve 1D graded lenses. Important results regarding the design, manufacturing and experimental characterization of a flat lens GRIN operating in X-band microwaves are deferred. This lens focuses an incident plane wave and collimates the wave emitted by a point source located in its focal plane. If this lens is itself a demonstrator and validates the approach implemented for the design, its potential applications particularly concern antennas. We also carry several 2D graded lenses including Lüneburg and Half Maxwell Fisheye lenses; their applications to the antennas are important. We are also interested in making optical graded index lenses called "SELFOC®".In order to confirm the remarkable dispersive properties that have been identified, we continued in that direction by revisiting a classic experiment that highlights the existence of evanescent waves: the "double right angle prism". We also highlight the phenomenon of "frustrated total internal reflection" and the shift discovered by Goos and Hänchen suffered by the reflected wave on the interface. It's these two points – frustrated total internal reflection and Goos-Hänchen effect - that we check in the case of LHI photonic crystals
Zheng, Xin. "Graded photonic crystal for silicon photonics." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPAST063.
Gradient photonic crystals (GPhCs) enable the engineering of their effective index, opening up new degrees of freedom in photonic device design. They can be understood through gradient index optics (GRIN optics), which describe inhomogeneous media in which light does not propagate along straight paths. This makes it possible to consider any index profile. This makes GPhCs particularly attractive for the miniaturization of optical components, especially in silicon photonics. They are based on the variation of a parameter of the photonic crystal elemental cell (PhC); here, the filling factor is varied so that the effective index of the GPhC achieves the desired index profile. The aim of this thesis is to explore the potential of GPhCs by designing graded-index devices on the Silicon-On-Insulator (SOI) "platform" at telecom wavelengths. The complete chain from design to device characterization, including simulation and manufacturing, is implemented. We focused on two typical gradient index optics instruments: the Mikaelian lens and the Half Maxwell Fish Eye (HMFE). In this thesis, we propose a new effective index approximation method for the SOI "platform", which we have validated by designing a Mikaelian lens (with a hyperbolic secant index profile). For such devices, two effective indices need to be taken into account: that of the guided mode in the Silicon layer and that of the PhC. In this method, the effective index of the PhC is first calculated to replace the index of the guided mode layer; then the effective index of this layer is calculated. Simulation results obtained using commercial software (FDTD method) show that the lens designed in this way satisfies the analytical predictions, contrary to the results obtained with commonly used methods. We then applied it to HMFE.The devices were then fabricated in the cleanroom by electron beam lithography (EBL) and plasma etching (ICP). The individual GPhCs consisted of periodically distributed air holes in the Silicon layer, with a minimum diameter of around 40 nm. They were then characterized in two stages, notably by near-field microscopy (SNOM). These devices are only a few wavelengths thick (approx. 3 or 5 λ_0), while their focal spot width is close to the diffraction limit (approx. 0.5 λ_0). They operate over a wavelength range of around 150 nm. The Mikaelian lens results have been used to develop a mode size converter (taper), which is effective over a few wavelengths. It is ten times shorter than a conventional converter. In this thesis, we also show how it is possible to interpret EM wave propagation in these graded-index components on the SOI platforms using the multimode interferometer principle. As they propagate, the different modes accumulate a phase difference, resulting in a mode beat that modifies the EM field distribution, leading to focusing. The characteristic length of this mode beat is equal to the focal length. All these devices are studied for integration into integrated photonics circuits
Nouvelot, Luc. "Evaluation et réalisation de miroirs diélectriques à profil d'indice continu et périodique (filtres rugates)." Grenoble 1, 1993. http://www.theses.fr/1993GRE10069.
Sanchez, Sandrine. "Croissance par M. O. V. P. E. Et caractérisation d'hétérostructures ZnCdSe à gradient d'indice et à confinement séparé." Montpellier 2, 1997. http://www.theses.fr/1997MON20085.
Farhaoui, Amira. "Les oxynitrures de silicium déposés par pulvérisation en gaz réactif pulsé pour des dispositifs antireflets à gradient d'indice de réfraction." Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22711/document.
Antireflective systems (ARS) are of great importance for photovoltaic (PV) cells, especially those of second generation based on thin layers. In this work, we have been looking for achieving an ARS not only efficient but also meeting the criteria of the PV industry in terms of production cost and ease of implementation. For this, we particularly studied the deposition of silicon oxynitrides (SiOxNy), as the base materials of these devices. Films were deposited by cathodic reactive radiofrequency sputtering with a magnetron effect. We desired to study not only the deposition process, the obtained materials but also the realization of functional devices. We firstly presented two routes of SiOxNy thin films deposition: by the Conventional Process (CP) where the reactive gases are not pulsed, and by the Reactive Gas Pulsing Process (RGPP). We also combined an experimental study by Optical Emission Spectroscopy (SEO) and process modeling to better understand the reactive gases interactions with the target and their effect on the process. Simultaneously, films depositions were realized to check the potential of each technique to obtain a wide range of silicon oxinitrides composition.Then, we studied the effect of pulse parameters with the RGPP on the structure and also on the optical and electrical properties of SiOxNy thin films. We aimed here to confirm the link between structure and refractive indices for these films. Finally, to achieve a functional AR device, AR systems were firstly simulated with an electromagnetic calculation program and optimized using a genetic algorithm. The optimized systems were then deposited and characterized. An average reflectivity (between 400 and 900 nm) less than 5% was thus reached
Cabeza, Stéphane. "Réalisation, caractérisation et optimisation de lentilles optiques de grandes dimensions à gradient d'indice radial en matériaux polymères : applications pour la correction de la vue." Mulhouse, 1997. http://www.theses.fr/1997MULH0461.
Chaffanjon, Pierre. "Optimisation de l'attenuation et de la dispersion des fibres optiques polymeres par l'utilisation de materiaux deuteries et par la realisation de preformes a gradient d'indice." Université Louis Pasteur (Strasbourg) (1971-2008), 1990. http://www.theses.fr/1990STR13035.
Luttmann, Michel. "Ellipsométrie spectroscopique à angle variable : applications à l'étude des propriétés optiques de semi-conducteurs II-VI et à la caractérisation de couches à gradient d'indice." Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10232.
Crépeau, Joël. "Development of a single-mode interstitial rotary probe for In Vivo deep brain fluorescence imaging." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/29428/29428.pdf.
This thesis documents the expertise developed by the author at the Centre de recherchede l’Institut universitaire en santé mentale de Québec (CRIUSMQ) in fibered endoscopy,particularly the design and construction of a new kind of optical microscope: ThePanoramic Interstitial Microscope (PIM). Through the juxtaposition of a short piece ofGraded-Index fibre and a prism at the end of a single-mode fibre, laser light is focussedon the side of the probe. To form an image, the latter is quickly spun around its axiswhile it is being pulled vertically by a piezoelectric actuator. This minimally invasivefluorescence rotary interstitial imaging system is an endeavor to limit the damage causedby the probe while imaging enough tissue to provide good context to the user in deep brain optical imaging.
Maudet, Florian. "Couches nanostructurées par dépôt en incidence oblique : corrélations microstructure et propriétés optiques pour application aux traitements antireflets hautes performances dans le visible étendu et l'infrarouge." Thesis, Poitiers, 2018. http://www.theses.fr/2018POIT2295/document.
Anti-reflective (AR) coatings are widely used to improve the transmission of optical systems composed of window, lenses, separating filters,... In this thesis, the spectral ranges targeted are the extended visible [400-1800nm] and the mid infrared [3.7-4.8µm]. Thin film deposition nanostructuring method using oblique angle deposition (oblique angle deposition) PVD technique was chosen because it allows high performance AR to be considered over a wide wavelength range, by an industrial process. The introduction of porosity with the control of deposition angle is used to nanostructure the architecture of each layer and stack; a method for modifying and optimizing the optical properties of the constituent layers for optimal complete design. A mapping of the effective indices accessible by OAD has been identified for the three materials deposited (TiO2, SiO2 and Ge). However optical properties of these nanostructured layers differ greatly from those of dense layers due to the presence of anisotropy, index gradient, diffusion and absorption. Based on advanced microstructural, chemical and optical characterizations (AFM, SEM, TEM, FIB tomography, TEM tomography, EDX, EELS, spectrophotometry and generalized ellipsometry) a more complex analytical optical model coupled with finite element analyses (FDTD) is presented. All the work has enabled OAD to develop simple two-layer anti-reflective coatings that already demonstrate high levels of transmission, superior to existing (interferential) or work in progress (Moth-eyes) AR treatments
DERROUGH, SAMIR. "Reseaux polymeres interpenetres a gradient d'indice de refraction." Université Louis Pasteur (Strasbourg) (1971-2008), 1993. http://www.theses.fr/1993STR13028.
Bouchon, Patrick. "Ingénierie d'indice optique à base de nanostructures métalliques." Phd thesis, Palaiseau, Ecole polytechnique, 2011. https://pastel.hal.science/docs/00/64/20/68/PDF/Memoire_PBouchon_17112011.pdf.
Plasmonic nanostructures are supporting plasmonic resonances which allow to confine the electromagnetic field and to govern the light behavior at a subwavelength scale. This thesis first deals with absorbing plasmonic structures. I have simulated, fabricated and characterized vertical metal / insulator / metal resonators (high aspect ratio grooves) which exhibit a total absorption in the infrared range. Besides, I have study the strong coupling regime in these resonators which led to very high quality factor. I show that it is also possible to couple several resonators to achieve photon sorting or widening of the absorption band. Furthermore, plasmonic devices are getting more and more complex, and their fast design can be achieved through a reduction of the computation time. I developed a modal method based on B-splines which allows, thanks to sparse matrices, to hasten the computations. Such methods can be used with a metaheuristic algorithm for the design of optical functions, e. G. A wide band absorber or a bandpass filte
Bouchon, Patrick. "Ingénierie d'indice optique à base de nanostructures métalliques." Phd thesis, Ecole Polytechnique X, 2011. http://pastel.archives-ouvertes.fr/pastel-00642068.
Kumar, Raj. "Fabrication et étude de matériaux "mous" à gradient d'indice acoustique." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0186.
This thesis is devoted to the fabrication and the study of a novel class of acoustic gradient index (GRIN) materials for the manipulation of waterborne acoustic waves. As in optics, acoustic GRIN are inhomogeneous materials, in which the acoustic refractive index n =C_(L,water/air)/C_(L,material) varies as a function of the position inside the material. Here, C_(L,water/air) and 〖 C〗_(L,material) are the acoustic wave speeds in a reference medium (water for underwater acoustics) and in the material respectively. We here describe the fabrication of ultrathin (i.e. sub-wavelength) GRIN materials named “Soft acoustic gradient index metasurfaces” engineered from soft graded-porous silicone rubbers with a high acoustic index for broadband ultrasonic three-dimensional wave-front shaping in water
Helmers, Hakon. "Optique intégrée appliquée à la détection de variation d'indice optique par onde évanescente." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0033.
Rondineau, Sébastien. "Modélisation de lentilles sphériques à gradient d'indice et sources conformes associées." Rennes 1, 2002. http://www.theses.fr/2002REN10125.
Guénette, Jason. "Conception d'une lentille axicon à gradient d'indice de réfraction GLA (GRIN Lens Axicon)." Master's thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/33848.
Axicons are mostly known for their capacity to produce Bessel beam. However, some axicon has the propriety to produce annular focusing whether directly or by adding a lens. In this text we have study the possibility to produce an axicon with gradient index of refraction that produce an annular focusing. More precisely we study the possibility to produce a component which incorporates the linear function of a conical lens and the parabolic function of a lens. The study refraction index profile has a radial variation and allow to a periodic annular focalisation. A similar refractive index profile has already been study by E. Marchand then by Rosa M. However, the solutions proposed by them are approximate solutions and their studies are limited. Some optical fiber already has index profile like the one we are interest so this axicon have the potential to be use for optical fiber application. We have demonstrated theoretically the exact refractive index profile that produce annular focusing and we have demonstrated theoretically that the ring produce is of good quality. We have also studied the possibility to produce a Bessel beam with this device that we name GLA (Grin Lens Axicon) and the simulation show that the beam could be of excellent quality. Some experimental tests have been done to show that it is possible to produce a Bessel beam with a GLA.
Thon-Adjalin, Carolle. "Étude d'un système de transmission sur fibre optique plastique à saut d'indice." Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28166/28166.pdf.
Setzu, Susanna. "Réalisation et étude de structures à modulation d'indice optique en silicium poreux." Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE10243.
Stojcevski, Dragan. "Développement d'un contrôle optique multicritère : application à la détermination d'indice in situ." Thesis, Ecole centrale de Marseille, 2016. http://www.theses.fr/2016ECDM0003/document.
The performances of complex interference filters meets today to exigent specifications and permit to enhance the physical limits of optical instruments in which they are integrated. During the manufacturing of a filter, it is obviously important to monitor with very high accuracy (typically sub-nanometric) the thickness of the deposited layers. This requires the use of an in situ measurement of the optical characteristics of the multilayer during the process.In the framework of this thesis, we have developed a new optical monitoring system which makes possible to achieve the simultaneous measurement of the transmittance of a multilayer filter, on one hand at a single wavelength defined by the user in the spectral range between 350 nm and 1000 nm (monochromatic monitoring with a resolution of 0.35 mm), and on the other hand on this whole spectral range at single shot (broadband monitoring with a resolution of 3 nm). These two measurements are made in 6 milliseconds at a rate of 2 Hz (corresponding to the rotation speed of the substrate holder), and are perfectly synchronized. In addition, the substrate holder tray is designed with a reference channel corresponding to a void position (without sample). Thanks to that configuration the monitoring system has a very high stability and accuracy better than 0.001. Finally, a numerical method has been developed to enable the comparison of the results provided by the two acquisition channels (monochromatic and broadband) taking into account the difference of their spectral resolution.This system opens the way for the use of several independent criteria to determine in real time the exact moment when the deposition of a layer must be stopped (turning point monitoring, trigger point monitoring, broadband monitoring, achievement with time monitoring using an optical in situ determination of the deposition rate). So this is indeed an all optical multi-criteria monitoring systems.This first application of this system has involved the determination of the optical constants (refractive index and extinction coefficient) of a high index dielectric material: the tantalum pentoxide. The method used is based on a recording of the evolution of the transmitted spectrum of a witness sample during the growth of the layer (broadband channel) and a processing, wavelength by wavelength, of the timing data profile of that evolution. This new method does not require any descriptive spectral dependence law for each of the two optical constants. It also paves the way for an analysis of the behavior of the refractive index of a layer in function of the thickness. Finally, it is applicable to low index materials, such as, for example, silica
Albert, Olivier. "Variations d'indice non linéaire en régime femtoseconde : effets directs et effets en cascade." Phd thesis, Paris 11, 1998. http://tel.archives-ouvertes.fr/tel-00011667.
- la réalisation d'un amplificateur paramétrique optique femtoseconde permettant de disposer de longueurs d'onde dans l'infrarouge proche.
- un système expérimental de mesure de phase permettant de mesurer l'évolution temporelle de phases non linéaires.
- des mesures de fréquences de phonons optique dans des cristaux pérovskites. La détermination théorique et expérimentale du vecteur d'onde associé au phonon a permis de séparer deux processus expérimentaux différents.
- la mesure de la dynamique temporelle du déphasage induit par une cascade de non linéarités du second ordre lors de la génération de fréquence somme. Les résultats ont montré que le déphasage n'est pas assimilable à un phénomène instantané et que le décalage temporel de fréquence associé est non linéaire.
Robichaud, Louis-Rafaël, and Louis-Rafaël Robichaud. "Génération de supercontinuum dans l'infrarouge moyen à partir de fibres optiques à saut d'indice." Master's thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/38229.
Ce mémoire porte sur la génération de supercontinuum (SC) dans l’infrarouge moyen (mid-IR) à partir de fibres optiques à saut d’indice en vue d’aider l’innovation de la prochaine génération de systèmes lasers spectroscopiques autant en télédétection qu’en microscopie. Une revue exhaustive de littérature ainsi qu’une explication des bases théoriques de la génération de SC mid-IR sont présentées. Deux résultats d’impact ont été obtenus au cours des travaux. D’abord, le premier SC de type cascade s’étalant jusqu’à 8 μm a été démontré, et ce via une fibre optique d’AsSe monomode par un pompage d’impulsions picosecondes amplifiées. Ensuite, le premier SC atteignant une puissance moyenne de l’ordre du watt a été démontrée dans une fibre d’AsSe/AsS. Ce dernier résultat a été possible grâce au développement d’un laser à fibre ultrarapide amplifié émettant des impulsions hautement énergétiques à 3.6 μm et, aussi, à la déposition d’une couche mince antireflet d’Al2O3.
This thesis focuses on the generation of supercontinuum (SC) in the mid-infrared (mid- IR) from step-index optical fiber in order to help the next generation of spectroscopic laser systems in both remote sensing and micro-spectroscopy applications. A comprehensive review of the literature as well as an explanation of the theoretical basis of mid-IR SC generation is presented. Two impact results were obtained during the master. First, the first cascaded SC up to 8 μm was demonstrated via a single-mode AsSe optical fiber by pumping with amplified picosecond pulses. Then, the first SC reaching an average power in the watt-level was demonstrated in an AsSe fiber, thanks to the amplified femtosecond fiber laser emitting high energy pulses at 3.6 μm and the deposition of a Al2O3 anti-reflection coatings.
This thesis focuses on the generation of supercontinuum (SC) in the mid-infrared (mid- IR) from step-index optical fiber in order to help the next generation of spectroscopic laser systems in both remote sensing and micro-spectroscopy applications. A comprehensive review of the literature as well as an explanation of the theoretical basis of mid-IR SC generation is presented. Two impact results were obtained during the master. First, the first cascaded SC up to 8 μm was demonstrated via a single-mode AsSe optical fiber by pumping with amplified picosecond pulses. Then, the first SC reaching an average power in the watt-level was demonstrated in an AsSe fiber, thanks to the amplified femtosecond fiber laser emitting high energy pulses at 3.6 μm and the deposition of a Al2O3 anti-reflection coatings.
Diallo, Alpha Ousmane. "Modélisation hyperfréquence de problèmes multi-échelles appliquée au cas des antennes à métamatériaux diélectriques." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066356/document.
This work focuses on the improvement of the antennas compactness used primarily for embedded systems while respecting the performance and competitiveness requirements. The approach explored consists in using artificial materials operating in transmission and designed by structuring the dielectric material on a scale smaller than the wavelength (sub-wavelength). This structuring makes it possible in practice to achieve a variation in the effective refractive index in order to produce diffractive elements capable of performing a microwave function. However, the particularity of this type of structured element is to mix several physical scales generating complexity in their study. The largest dimension of a structured component can reach several tens of wavelength, for example 20λ, while the minimum size of the sub-wavelength structures may be less than a fraction of the wavelength, as than λ / 20. This multi-scale aspect increases the simulation times of antenna devices integrating these structured elements, thus preventing any possibility of multi-parameter optimization in reasonable times. In order to exploit fully the potential of these structured materials, a numerical model of computation has been developed on the basis of optical paths. This model gives results on the maximum gain of structured diffractive lens antennas with an accuracy of 0.5 dB. The computation time of the model is of the order of the minute compared to more than 6 hours for a complete simulation with the electromagnetic calculation software CST Microwave Studio. The speed and precision of this model have been used to optimize the design of a structured diffractive lens. To illustrate the relevance of this structured approach, its performances were compared with those of Fresnel lens antenna and hyperbolic lens antenna. This comparison was carried out under identical footprint conditions with a length to diameter ratio L / D of 0.5. The gain of the structured lens was found to be 1.6 dB higher than the Fresnel lens and 2.7 dB higher than the hyperbolic lens
Tsyier, Sergei. "Caractérisation des profils d'indice de réseaux de Bragg innovants en module et phase." Electronic Thesis or Diss., Paris, ENST, 2013. http://www.theses.fr/2013ENST0022.
N the last decade new techniques were developed for fabrication of sophisticated Fiber Bragg Gratings (FGBs). This has been motivated by the emergence of many applications such as dispersion compensation for long-haul communication systems, DFB fiber lasers, optical add/drop multiplexers, and optical sensors. Post-fabrication diagnostics should provide relevant information to enhance the FBG fabrication process. It is well known that the FBG spectral properties are related to the index profile Δn. Direct measurement techniques, such as the side diffraction method reported by P. Krug, allow determining the index modulation amplitude along the FBG. Nevertheless, these techniques provide no information about phase fluctuations. An alternative method of indirect characterization, based on the Layer-Peeling (LP) algorithm, consists in Bragg grating profile reconstruction from its complex reflectivity. However, the LP method is unstable when applied to characterize long FBGs (>1mm) due to the error propagation effect. In this thesis we have shown the principle of a novel technique for the direct measurement of amplitude and phase variations of the index modulation along an FBG based on the blue luminescence (BL). Our experimental results are in a good agreement with the according Krug characterization. The proposed method of FBG characterization in amplitude and phase using the UV induced BL can be applied to long gratings (up to tens of centimeters) having complex index modulation profiles. It allows retrieving simultaneously the index profile modulation Δnac(z) and the chirp function, localizing phase shifts, and also detecting the mean index change Δndc(z)
Latard, Véronique. "Méthodes de visualisation par gradient d'indice en mécanique des milieux non homogènes : application à la diffusion acoustique et aux écoulements diphasiques." Lille 1, 1998. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1998/55376-1998-5.pdf.
Paré, Nanouk. "Méthode d'inversion de l'épaisseur optique des aérosols, à partir d'images satellitaires de télédétection, basée sur un nouveau modèle d'indice atmosphérique (ATIM)." Mémoire, Université de Sherbrooke, 2001. http://savoirs.usherbrooke.ca/handle/11143/2286.
Paré, Nanouk. "Méthode d'inversion de l'épaisseur optique des aérosols, à partir d'images satellitaires de télédétection, basée sur un nouveau modèle d'indice atmosphérique (ATIM)." Sherbrooke : Université de Sherbrooke, 2002.
Tsyier, Sergei. "Caractérisation des profils d'indice de réseaux de Bragg innovants en module et phase." Thesis, Paris, ENST, 2013. http://www.theses.fr/2013ENST0022/document.
N the last decade new techniques were developed for fabrication of sophisticated Fiber Bragg Gratings (FGBs). This has been motivated by the emergence of many applications such as dispersion compensation for long-haul communication systems, DFB fiber lasers, optical add/drop multiplexers, and optical sensors. Post-fabrication diagnostics should provide relevant information to enhance the FBG fabrication process. It is well known that the FBG spectral properties are related to the index profile Δn. Direct measurement techniques, such as the side diffraction method reported by P. Krug, allow determining the index modulation amplitude along the FBG. Nevertheless, these techniques provide no information about phase fluctuations. An alternative method of indirect characterization, based on the Layer-Peeling (LP) algorithm, consists in Bragg grating profile reconstruction from its complex reflectivity. However, the LP method is unstable when applied to characterize long FBGs (>1mm) due to the error propagation effect. In this thesis we have shown the principle of a novel technique for the direct measurement of amplitude and phase variations of the index modulation along an FBG based on the blue luminescence (BL). Our experimental results are in a good agreement with the according Krug characterization. The proposed method of FBG characterization in amplitude and phase using the UV induced BL can be applied to long gratings (up to tens of centimeters) having complex index modulation profiles. It allows retrieving simultaneously the index profile modulation Δnac(z) and the chirp function, localizing phase shifts, and also detecting the mean index change Δndc(z)
Zymelka, Daniel. "Suivi par methode optique du frittage micro-ondes d'oxydes ceramiques." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2012. http://tel.archives-ouvertes.fr/tel-00821161.
Hamamda, Mehdi. "Perspectives nouvelles pour l'optique atomique en jets : Interaction de van der Waals-Zeeman et milieux d'indice négatif pour les ondes de matière." Phd thesis, Université Paris-Nord - Paris XIII, 2011. http://tel.archives-ouvertes.fr/tel-00632807.
Hespel, Camille. "Extension de l'Anémométrie Phase Doppler à la mesure d'indice de réfraction et développement de la vélocimétrie laser par corrélation." Rouen, 2007. http://www.theses.fr/2007ROUES015.
The aim of numerical and experimental study presented in this thesis is to improve optical diagnostics in order to understand the atomization and evaporation processes. A better understanding of such processes permits a better control of combustion. The evaporation, the thermochemical evolution of droplets and measurements in dense medium are still challenges. The size-velocity correlation in diluted medium is given by Phase Doppler anemometry. The objective of the simulations is to examine the possibility to extend the Phase Doppler Anemometry by refractive index measurement. The proposed extension called Glare Spot Phase Doppler Anemometry is based on the analysis of glare points of reflection and refraction in image plane of a droplet in PDA volume control. The potentialities and limitations of this technique are studied in this thesis. Another difficulty to study the atomization is the strong density of spray close to injector orifice. The Laser Correlation Velocimetry gives the axial velocity of structures, cross a focalised laser beam, by the measurement of a flight time by correlation. During my thesis this technique was validated and established in laboratory
Vuillermoz, Annick. "Etude expérimentale et modélisation de l'inhomogénéité chimique isotrope et anisotrope de cristaux isotypes de KTiOPO#4. Application à l'élaboration de cristaux à gradient de concentration et étude des propriétés optiques non linéaires spécifiques." Dijon, 1997. http://www.theses.fr/1997DIJOS051.
Maras, Afaf. "Etude expérimentale et numérique des contraintes résiduelles dans des structures à double gradient de contraintes." Troyes, 2010. http://www.theses.fr/2010TROY0010.
The knowledge of residual stresses allows a reliable prediction of the evolution of structure performances, and its service life. On this study, we present a new method for residual stresses determination. This method is applied particularly to structures that contain a stress gradient in depth and in surface, like it can be found in welded structures. The internal stress field is mechanically perturbed with the incremental machining of a groove. The mechanical equilibrium is modified in tow directions. A new state of stress is created in the structure when the stress field is mechanically disturbed. The structure finds a new equilibrium state generating displacements on the surface. These displacements are measured using the Electronic Speckle Pattern Interferometry (ESPI). The measured displacements field is linked to residual stresses using calibration coefficients calculated with the element finite method. We obtain a representation of the residual stress field in two directions, in-depth and along groove. The utilization of this method for the study of ultrasonic shot-peening is presented. We present also a method for the introduction of a residual stress field in a finite elements model. This method is applied to an Almen strip, its generalization for complexe geometries will allow to use the residual stress field as an initial condition for ameliorated numerical simulations of structure
Zhao, Jinfeng. "Phononic Crystals to Control the Propagation of Elastic Waves." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066098/document.
This manuscript is about the focusing of elastic beams propagating in a plate or on the free surface of a semi-infinite medium, using flat acoustical lenses. The devices we have studied are based onto 2D phononic crystals that are made of air inclusions in a solid matrix and featuring a gradient of their elastic properties along one direction of the lens. The gradient index (GRIN) is obtained by modulating either the size of the air inclusions or the distance between two consecutive inclusions.We primarily adopted a computational approach but a significant part of the work concerns the analytical calculation of the ray trajectories as well as the experimental check of the theoretical findings. The analytical approach consists to calculate the ray trajectories of an elastic waves within the lens while accounting for the anisotropy along each lines of inclusions. The analysis applied to the lowest-order flexural Lamb wave (A0), together with both the numerical results and the experimental data, well explains the features of the displacements field in the focus area, including the location, shape and lateral width. The formalism applies whatever the symmetry of the phononic crystal is and can be extended to other polarization of the elastic wave. We show in this work that FWHM as small as 0.64 may be obtained when focusing inside the lens.The formalism applies also to the focusing behind the lens. In that case, the resolution at the focus is determined by the “maximum transverse wavenumber” at the exit of lens, in good agreement with the numerical and experimental results. Then we designed a GRIN phononic lens featuring resonant pillars in addition to the constitutive air inclusions. The numerical analysis foresees the resolution at the focus beyond the diffraction limit, while experimentally we measured the resolution to be just above the diffraction limit. Lastly, we turned to the subwavelength focusing of Rayleigh waves through GRIN lenses. We found a good agreement between the ray trajectories calculation, the numerical simulations and the experiments. We further analysed the influence of energy transmission when the focus is located behind the lens
Loriot, Vincent. "Alignement moléculaire par impulsions laser ultrabrèves : Mesures & Applications." Phd thesis, Université de Bourgogne, 2009. http://tel.archives-ouvertes.fr/tel-00660050.
Miché, Pierre. "Automatisation d'un spectromètre intégral à étalon de Fabry-Perot : développement d'un capteur d'indice à haute résolution, commandé par ordinateur." Rouen, 1987. http://www.theses.fr/1987ROUES012.
Soulard, Rémi. "Réseaux d'indice et réseaux de gain dans les milieux lasers solides dopés Nd3+ ou Yb3+ Utilisation pour le mélange à deux ondes et les cavités laser auto-adaptatives." Phd thesis, Université de Caen, 2011. http://tel.archives-ouvertes.fr/tel-00576567.
Polge, Géraldine. "Etude de la faisabilité d'un système de cartographie de dose par stimulation optique et application à la radiothérapie à haut gradient de dose." Montpellier 2, 2001. http://www.theses.fr/2001MON20190.
Rouxel, Yann. "Coévaporation avec masquage mécanique de ZnSe et de LaF3, pour la réalisation de couches minces à profils d'indice continus périodiques." Université Joseph Fourier (Grenoble), 1996. http://www.theses.fr/1996GRE10096.
Costes, Sylvain. "Extension de l'approche par la courbe maitresse de la prédiction des durées de vie de réseaux d'indice complexes inscrits par UV dans les fibres." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00917592.
Sawant, Rajath Ravindra. "Métasurface à gradient de phase diélectrique pour les applications d'optique classique et quantique." Thesis, Université Côte d'Azur, 2020. http://www.theses.fr/2020COAZ4096.
In recent years, various optical functionalities have been demonstrated using metasurfaces which have attracted tremendous attention. Metasurfaces being diffractive optical components, show greater flexibility, including compactness, lightweight, arbitrary wavefront addressing capabilities exceeding those of refractive optical components. However, in terms of efficiency refractive components perform better and further optimization is required for metasurfaces in this direction. Considering this, here we design hybrid optical devices to combine the advantages of both the components. First, it is demonstrated how the dispersion of a simple optical element such as a prism can be mitigated using a metasurface. By employing phase gradient metasurfaces, the outgoing wavevectors can be controlled and hence the diffractive dispersion of metasurface. Utilizing this property, metasurfaces with relatively small phase gradients are designed and prism dispersion mitigation is experimentally demonstrated. Extending the same principle to lenses, metasurface to correct for lens chromatic aberration is designed in the wavelength range of 550-800nm. Also, it is shown that monochromatic aberration such as spherical aberration can also be corrected by designing an appropriate phase gradient for the metasurface. Analytical calculations, large area metasurface fabrication and comprehensive experimental characterization are done to demonstrate aberration correction of commercially available lenses. These developments are promising for future compact imaging systems. Realizing the potential of metasurfaces in classical optics, they are also used for Quantum optics applications. However, only a few works have been done in this direction. Hong Ou Mandel experiment, which is one of the basic experiments of Quantum optics, demonstrates quantum interference. Here, we propose to modify the original setup by replacing the beam splitter with a phase gradient metasurface. A novel metasurface is designed for this purpose called ‘Dual Gradient Metasurface’ which imparts additional functionality along with the beam splitter functionality. The nanofabrication of the metasurface is optimized to realize 50/50 transmission in the two diffracted orders to imitate a beam splitter. The superior control that metasurfaces offer over the phase, polarization and amplitude of light can be quite beneficial for manipulating the quantum states of light. This opens doors for harnessing the potential of metasurface for quantum technologies
Gorram, Mohamed. "Génération et étude de guides d'onde dynamiques et reconfigurables induits par illumination latérale." Thesis, Metz, 2009. http://www.theses.fr/2009METZ013S/document.
The realization transparent achievement of optical networks that do not need electronic components for the temporary detection and regenration of signals asks for optical routing and interconnection elements which are reconfigurable in short time, in the order of milliseconds in the case telecommunications networks. The use of optical waveguides in active materials made of active materials by conventional techniques, such as ion-indiffusion, proton exchange or ion implantation is badly suitable for this goal. These techniques give rise only to static waveguides close to the material surface and they are not easily modified. The technique of light inducing waveguides by lateral illumination developed in this work allows to cross an important step towards purely optical devices in which light is used to guide and manipulate light without resorting to complex manufacturing steps. The main advantage is that this effect can be erased, giving rise to dynamic structures that do note cause a permanent damage of the material. Another advantage is the versatility with respect to the form of the waveguides, that is defined by the structure imposed to control the illumination perpendicular to the direction of propagation. The feasibility of reconfigurable 1-dimensional waveguides has been experimentally demonstrated in the electro-optic ferroelectric crystals SrxBa1xNb2O6 (SBN, x=0.61) and Sn2P2S6 (SPS). The illuminating wavelengths used were 514 nm for SBN and 633 nm for SPS. Response and reconfiguration times of the order of 1 ms are shown to be possible in the case of SPS. The dynamics of the waveguides has been studied on the basis of theoretical treatment and numerical simulations. The evolution of light induced one-dimensional waveguides when the sustaining electric field is switched off leads to a novel kind of dynamic light deflection. We have studied this effect in detail using SBN and LiTaO3 crystals. Simulations of the beam propagation in the split waveguide on the base of a simple model lead to a good agreement with the experimental observations. Light modulation by the help of this effect has been demonstrated as well. Finally, we realized for the first time, the recording of dynamically reconfigurable bulk channel waveguides confined in two dimensions using lateral illumination technique. The experimental studies of the dependence of the output probe wave profile on the intensities of two control waves and on the applied electric field were found to be in good agreement with the expectations based on a simplified step profile for the photorefractive by induced refractive index change and on mode calculations
Moreau, Aurélie. "Réseaux de Bragg intracavité en milieu amplificateur." Phd thesis, Télécom ParisTech, 2006. http://pastel.archives-ouvertes.fr/pastel-00001975.
Renard, vincent. "Alignement de molécules linéaires par impulsions laser de courtes durées." Phd thesis, Université de Bourgogne, 2005. http://tel.archives-ouvertes.fr/tel-00009705.
Devisme, Céline. "Etude de l'influence des disparités horizontales et verticales sur la perception de la profondeur en champ visuel périphérique." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://tel.archives-ouvertes.fr/tel-00276430.
Zhu, Chao. "Effective and efficient visual description based on local binary patterns and gradient distribution for object recognition." Phd thesis, Ecole Centrale de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00755644.