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Organic photorefractive materials

About: Organic photorefractive materials is a research topic. Over the lifetime, 697 publications have been published within this topic receiving 13041 citations.


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Proceedings ArticleDOI
20 Sep 1999
TL;DR: In this paper, the index grating amplitude (Delta) n is computed from the equation derived from the Band Transport model for the photorefractive effect, and the value of (Delta n) n can be estimated from counting the number of peaks in the curve for the diffraction efficiency as a function of time under the phase matching condition.
Abstract: Several photorefractive crystals such as LiNbO3 or BaTiO3 can be used for optical information storage as well as key elements for optical signal processing due to their unique property, viz., their refractive index varies according to their incident light distribution. Thus, we can construct phase gratings inside the crystals by using interference of two light beams. The index grating amplitude (Delta) n can be computed from the equation derived from the Band Transport model for the photorefractive effect. Experimentally, the value of (Delta) n can be estimated from counting the number of peaks in the curve for the diffraction efficiency as a function of time under the phase matching condition. Its precision is about 13%. Here we report a new method improving the measurement precision to about 1% by adding the measurement for the diffraction efficiency as a function of angle mismatch. This precise measurement of (Delta) n allows us to quantify photorefractive effect with greater precision.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

1 citations

Journal ArticleDOI
TL;DR: In this article, the authors predict the formation of electrically and optically controlled photorefractive surface waves in liquid crystal, with orientational photore-fractive effects.
Abstract: We predict the formation of electrically and optically controlled photorefractive surface waves in liquid crystal, with orientational photorefractive effects. In contrast to the case for photorefractive surface waves in inorganic crystals, the penetration depth of photorefractive surface waves in liquid crystal can be controlled by means of the applied external electric field, while the position of the photorefractive surface waves in the liquid crystal can be controlled by means of the applied external electric field and the polarization of incident light beams.

1 citations

Proceedings ArticleDOI
14 Oct 1998
TL;DR: In this paper, orientational photorefractive effects observed in photoconductive liquid crystals (LCs) contained with three kinds of polymer, i.e., poly(methyl methacrylate) (PMMA), poly(vinyl alcohol) (PVA) and a side-chain liquidcrystalline polymer (SLCP1), were reported.
Abstract: We report orientational photorefractive effects observed in photoconductive liquid crystals (LCs) contained withthree kinds of polymer, i.e., poly(methyl methacrylate) (PMMA), poly(vinyl alcohol) (PVA) and a side-chain liquidcrystalline polymer (SLCP1). The morphology of the photorefractive composites depended on the kind of polymer strongly.In both PMMA and PVA cases, LC and polymer were phase-separated and the composites showed memory effects. InSLCP1 case, the phase-separation in the composite dose not occur and the high resolution could be achieved. In this case,the photorefractive Bragg gratIngs were generated and a high two-beam coupling gain coefficient (75 cm') with a lowapplied field of 4 V/pm was observed.Keywords: polymer dispersed liquid crystal, photorefractive effect, hologram, photoconductive effect,nonlInear optics, two-wave mixing, degenerate four wave mixing. 1. INTRODUCTION Photorefractive materials have attracted a lot of attention both from the point of view of fundamental science andpractical applications such as a real-time hologram, a high-density hologram record medium, and a medium of the phaseconjugation gh2 Since the photorefractive studies were extended into organic materials in 1990,

1 citations

Dissertation
01 Dec 1992
TL;DR: In this paper, the epitaxial growth of thin film optical waveguides of the photorefractive materials Bi12GeO20 and Bi12SiO20 onto heated zirconia substrates by pulsed laser deposition is reported.
Abstract: This thesis is concerned with the fabrication and characterisation of photorefractive planar waveguides by the techniques of pulsed laser deposition and ion-beam implantation. The formation of photorefractive waveguides is highly desirable for the miniaturisation of optical systems and provides compatibility with other integrated optical devices in current use such as waveguide lasers and optical fibre technology. The optical confinement inherent to waveguides also holds the key to a major speed up in the effective response time of the photorefractive effect. Up to three orders of magnitude decrease is forecast due to the intensity dependence of the photorefractive response time. This thesis reports the epitaxial growth of thin film optical waveguides of the photorefractive materials Bi12GeO20 and Bi12SiO20 onto heated zirconia substrates by pulsed laser deposition. The epitaxial nature and stoichiometry of the films are verified using x-ray diffraction analysis. Waveguide modes were observed with effective refractive indices in close agreement with theoretical predictions implying that the refractive index of the deposited film is similar to that of the bulk crystal. Pulsed laser deposition has also been used to fabricate waveguides from the chalcogenide glass lanthanum/gallium sulphide. The waveguides demonstrate many characteristic chalcogenide properties such as photo-bleaching, photo-diffusion and a photo-induced change in the refractive index. Ion-beam implantation has been successfully used to form planar waveguides in the photorefractive materials Bi12SiO20, SrxBa1-xNb206 and BaTiO3. The annealing of SBN waveguides and the effect on waveguide propagation loss is discussed. Photorefractive effects have been observed and characterised in BaTiO3. The expected decrease in the effective photorefractive response time (for a given input power) has been observed, owing to a combination of optical confinement within the waveguide and possible modification of charge-transport properties induced through implantation. Photorefractive two-beam coupling experiments exhibited a decrease in the response time of >10^2, and an unexpected reversal of the gain direction in the waveguide compared with that of the bulk crystal.

1 citations

Proceedings ArticleDOI
Baolai Liang1, Zhao-Qi Wang, Guo-Guang Mu, Jiuhong Guan, Ru-Lian Fu 
01 Jan 1999
TL;DR: In this paper, the modified coupled-wave theory fitting results are coincident with the experimental data, and they are used to fit the diffraction efficiency of a volume grating in a Ce:KNSBN photorefractive crystal.
Abstract: The polarization and the incident direction of the readout beam strongly affect the diffraction efficiency of a volume grating in a Ce:KNSBN photorefractive crystal. The modified coupled-wave theory fitting results are coincident with the experimental data.

1 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231
20211
20201
20181
20172
20165