Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 38 for “"photorefractive"”.
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Optical information processing using photorefractive BSO
… processing tasks are implemented using photorefractive BSO as a dynamic holographic medium. The physical basis for the mechanism which allows the implementation of these devices is studied.<br/><br/>The properties of BSO which make it particularly attractive as a processing medium are …
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Real-time optical intensity correlation using photorefractive BSO
Real-time optical intensity correlation using a photorefractive BSO crystal and a liquid crystal television is implemented. The underlying physics basis is considered, some specific techniques to improve the operation are proposed, and several optical pattern recognition tasks are …
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Properties and applications of the photorefractive material Ce:KNSBN
CeiKNSBN is a new photorefractive material in the KNSBN family, which has some advantages compared to other crystals. Based on two-wave mixing theory, different methods are used to investigate the photorefractvie properties of the Ce:KNSBN crystal. Most parameters of the CeiKNSBN crystal are in the …
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Spatiotemporal dynamics of a photorefractive phase-conjugate resonator
The spatiotemporal dynamics of a photorefractive phase-conjugate resonator (PPCR) is studied both experimentally and analytically. The resonator is a confocal cavity bounded by a dielectric mirror and a phase-conjugate mirror in a four wave mixing geometry. The effect of the Bragg mismatch, which …
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Gravitational effects on defect formation in melt grown photorefractive materials : bismuth silicate
… Bismuth Silicate, Bi12SiO20, (BSO) is a photorefractive material with outstanding properties including a fast response time and high sensitivity is studied. Its photorefractivity is due to a native defect whose exact nature and origin have not been unambiguously determined. Motivation for …
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Growth and characterization of high-purity and iron-doped photorefractive barium titanate
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1987.
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Energy transfer between surface plasmon polariton modes with hybrid photorefractive liquid crystal cells
In this thesis, a hybrid photorefractive liquid crystal cell structure with the addition of a thin 40nm Gold layer is proposed that demonstrates significant photorefractive control of Surface Plasmon Polaritons (SPP). The photorefractive effects are generated through optically controlling the …
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PHOTOREFRACTIVE CRYSTAL-BASED ACOUSTO-OPTIC IMAGING IN THE NEAR-INFRARED AND ITS APPLICATIONS
… adaptive interferometer scheme employing a GaAs photorefractive crystal (PRC). The PRC-based AO system operating at 1064 nm is described, along with the underlying theory, validating experiments, characterization, and optimization of this sensing and imaging apparatus. The spatial resolution of …
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Atom transfer radical polymerisation - towards the synthesis of a fully-functional photorefractive polymer
… methacrylate; Polar solvents; Fully-functional photorefractive polymer. 2
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Picosecond Dynamics of Free-Carrier Populations, Space-Charge Fields, and Photorefractive Nonlinearities in Zincblende Semiconductors
… to spectroscopy or device fabrication. The photorefractive effect is a nonlinear optical effect that occurs in solids, where transport of an optically-induced free-carrier population results in an internal space-charge field, which produces an index change via the linear electrooptic effect. …
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Photorefractives for fast optics
… the nonlinear optical<br/>properties of novel photorefractive materials and devices. The focus of the work is<br/>centred on bringing together the attractive attributes of inorganic and organic<br/>materials in a single hybrid device and to increase the photorefractive effect that …
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An updatable three-dimensional display via direct optical fringe writing of computer - generated holographic stereograms in photorefractive polymer
… holographic gratings into a novel photorefractive polymer. The photorefractive polymer in question has been developed by Nitto Denko Technical Corporation and has many attractive properties for the 3-D display application, including long image persistence, rapid erasure, high …
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Semiconductor nanocrystals for novel optical applications
… by the promise of enhanced spectral response, photorefractive polymeric composites photosensitized with semiconductor nanocrystals have emerged as an important class of materials. Here, we report on the photosensitization of photorefractive polymeric composites at visible wavelengths through …
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Measurement of the nonlinear refractive index (n2) and stimulated Raman scattering in optical fibers as a function of germania content, using the photorefractive beam coupling technique
… susceptibility [x^{(3)}]. In this work, the photorefractive beam coupling technique, also called induced grating autocorrelation (IGA), has been used to measure the nonlinear refractive index (n_2) and the Raman gain coefficient (g_R) of short lengths (z ~ 20 m) of optical fibers. In the IGA …
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Novel active waveguide devices in direct-bonded structures
… of similar length.<br/>Also demonstrated is a photorefractive iron-doped LiNbO<sub>3</sub> waveguide buried in non-photorefractive magnesium-doped LiNbO<sub>3</sub>. In optical limiting experiments this device demonstrates a change in optical density of 2 and photorefractive response time of 5 …
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The investigation of correlator systems utilizing object and frequency space filters
… and distortion invariant pattern recognition. A photorefractive joint transform correlator (JTC) using Bismuth Silicon Oxide (BSO) as a non-linear recording medium and a liquid crystal television as a spatial light modulator is implemented. The underlying physics is considered, some specific …
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Nonlinear optical studies of dye-doped nematic liquid crystals
… different types in the samples, and to study the photorefractive and the orientational responses of these samples. Furthermore, we tried to explain and model the dynamical behaviors of the observed grating formations. The experimental techniques employed in this study include asymmetric two-beam …
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Electrical and optical effects in hybrid liquid crystal cells
… crystal systems show strong electro-optic and photorefractive effects. In order to understand the optical performance of hybrid liquid crystals, it was essential that the electrical response of the system to the incident illumination levels and different amplitudes of applied electric field be …
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Dynamic holography in semiconductors and biomedical optics
… speed and diffraction efficiency. For instance, photorefractive crystals and polymers can have high efficiencies, but operate at low speeds. Conversely, photorefractive quantum-well devices have high speed, but suffer from low diffraction efficiencies.</p> <p>This thesis describes theoretical and …
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