Showing papers on "Organic photorefractive materials published in 1991"
01 Dec 1991
TL;DR: In this article, the properties of photorefractive crystals for Holographic Recording are discussed. But, the authors do not discuss the application of these crystals in the field of dynamic Holography.
Abstract: 1. The Phenomenon of Photorefraction.- 2. Holography, and Optical Information Processing Systems.- 3. Salient Features of Photorefractive Crystals for Holography.- 4. Formation of an Electric-Field Grating During Holographic Recording in PRCs.- 5. Light Diffraction from Anisotropic Volume Phase Gratings.- 6. Fundamentals of Dynamic Holography.- 7. The Physics of Electro-Optic Spatial Light Modulators.- 8. Spatial Light Modulators.- 9. Applications of Photorefractive Crystals.- Appendix: Photorefractive Crystals.- A10 Semiconductor Photorefractive Crystals.- A 11 Other Photorefractive Crystals and Media.- References.
295 citations
Patent•
06 Jun 1991
TL;DR: The photorefractive effect results in a change in the refractive index of bulk chalcogenide glass when it is exposed to certain wavelengths of light, in particular, sub-band-gap light as mentioned in this paper.
Abstract: The photorefractive effect results in a change in the refractive index of bulk chalcogenide glass when it is exposed to certain wavelengths of light, in particular, sub-band-gap light. The effect results in a variety of device structures including a fiber optic faceplate; an optical waveguide; a fiber tap; a lens and a Bragg grating. Methods for fabricating the various devices are described.
44 citations
TL;DR: In this paper, the transition metal dopants of chromium and rhodium altered the photorefractive properties of strontium-barium niobate and beam coupling experiments were performed to determine photore-fractive parameters such as the effective charge density, the grating formation rate, and dark conductivity.
34 citations
TL;DR: In this article, a band transport model that uses a single donor level with only electrons as free charge carriers, taking the nonlinear recombination of free charge carrier (owing to variation of the trap density) and the time dependence of the free-charge-carrier density into account is presented.
Abstract: Photorefractive and photoconductivity steady-state as well as time-resolved measurements have been performed in strongly reduced KNbO3. The recorded photorefractive gratings show a nonexponential dark decay and an intensity-dependent two-wave mixing gain. The measured photoconductivity depends sublinearly on light intensity. The observed behavior is interpreted in terms of a band transport model that uses a single donor level with only electrons as free charge carriers, taking the nonlinear recombination of free charge carriers (owing to variation of the trap density) and the time dependence of the free-charge-carrier density into account. An analytical solution for the nonexponential dark decay of the photorefractive grating is derived. As an application of this model the results of the photorefractive and the stationary and transient photoconductivity experiments are used to determine the model parameters (thermal excitation rate, photoexcitation cross section, recombination coefficient, acceptor and donor densities, and electron mobility).
21 citations
TL;DR: In this paper, photobleaching and photorefractive effects caused by intense pulsed laser irradiation at 532 nm have been observed simultaneously in a germanium-doped monomode fiber.
Abstract: Photobleaching and photorefractive effects caused by intense pulsed laser irradiation at 532 nm have been observed simultaneously in a germanium-doped monomode fiber. A decrease of up to 4.1*10/sup -4/ in the refractive index of the core at 633 nm was inferred from the change in the radiation pattern of a probe beam and also from the change in the cutoff wavelength of the LP/sub 11/ mode. The effect is attributed to the bleaching of preexisting Ge(1) color centers in the fiber. >
10 citations
TL;DR: In this paper, a real-time optical holographic correlation using Bi 12 TiO 20 photorefractive crystal at λ = 0.633 μm was reported.
9 citations
TL;DR: The phase between the interference pattern and the photorefractive holographic grating and also between the signal beam intensity oscillations and the external ac field applied to the crystal have been investigated under coupling of the two waves with different frequency as discussed by the authors.
6 citations