Добірка наукової літератури з теми "Optique à gradient d'indice"
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Статті в журналах з теми "Optique à gradient d'indice":
-Marcou, J. "Les fibres optiques plastiques perfluorées et à gradient d'indice." Revue de l'Electricité et de l'Electronique -, no. 03 (1998): 84. http://dx.doi.org/10.3845/ree.1998.031.
Mure-Ravaud, A., and R. Rougny. "Effet de l'irradiation par des neutrons sur les caractéristiques temporelles d'une fibre optique à gradient d'indice." Optical and Quantum Electronics 18, no. 1 (January 1986): 43–48. http://dx.doi.org/10.1007/bf02069359.
Verrier, I., and J. P. Goure. "Etude des fluctuations d'intensité issue d'une fibre optique multimodale à gradient d'indice couplée partiellement avec une surface détectrice circulaire." Revue de Physique Appliquée 22, no. 2 (1987): 139–44. http://dx.doi.org/10.1051/rphysap:01987002202013900.
Soulie, L. "Anomalies des courbes experimentales donnant le gradient d'indice et permettant la determination du coefficient de diffusion de translation." Journal of Polymer Science Part C: Polymer Symposia 30, no. 1 (March 7, 2007): 109–16. http://dx.doi.org/10.1002/polc.5070300114.
Bognounou, Fidèle, Adjima Thiombiano, Patrice Savadogo, Joseph Issaka Boussim, Per Christer Oden, and Sita Guinko. "Structure et composition spécifique de la végétation ligneuse de quatre sites sur un gradient latitudinal au Burkina Faso occidental." BOIS & FORETS DES TROPIQUES 300, no. 300 (June 1, 2009): 29. http://dx.doi.org/10.19182/bft2009.300.a20412.
Amar, Bineta, Mame Samba Mbaye, Alfred Kouly Tine, Ndongo Diouf, Jules Diouf, Samba Laha Ka, Birane Dieng, and Kandioura Noba. "Impact de la salinité sur la diversité floristique dans la vallée de Bakhala (Fatick, Sénégal)." International Journal of Biological and Chemical Sciences 16, no. 2 (July 8, 2022): 628–41. http://dx.doi.org/10.4314/ijbcs.v16i2.10.
Sun, Qi, Quanjun Jiao, Xidong Chen, Huimin Xing, Wenjiang Huang, and Bing Zhang. "Machine Learning Algorithms for the Retrieval of Canopy Chlorophyll Content and Leaf Area Index of Crops Using the PROSAIL-D Model with the Adjusted Average Leaf Angle." Remote Sensing 15, no. 9 (April 25, 2023): 2264. http://dx.doi.org/10.3390/rs15092264.
Дисертації з теми "Optique à gradient d'indice":
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.