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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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Journal ArticleDOI
TL;DR: In this paper, the frequency dependence of the photorefractive effect is considered and the analysis results in a second-order model with an explicit dependence on both the grating spacing and the temporal grating frequency.
Abstract: The frequency dependence of the photorefractive effect is considered. The frequencies can be applied by introducing a temporal phase shift in one of the beams in a two-wave mixing configuration. The analysis of the Kukhtarev equations is based on the small modulation approximation, but in contrast to earlier papers, no a priori approximations are made. The analysis results in a second-order model with an explicit dependence on both the grating spacing and the temporal grating frequency. Curves for the modulus and the imaginary part of the space-charge field are obtained, and it is concluded that, for small fringe spacings, the second-order model presented provides important information on the photorefractive effect. >

25 citations

Journal ArticleDOI
TL;DR: In this article, the general equations applicable to the description of different photorefractive effects in electro-optic crystals, taking into account their piezoelectric properties, have been considered.
Abstract: The general equations applicable to the description of different photorefractive effects in electro-optic crystals, taking into account their piezoelectric properties, have been considered in this paper. The photorefractive gratings formed by plane light waves slowly changing in time in boundless piezoelectric media have been analyzed in detail. The influence of piezoelectric properties of the crytals on the effective static dielectric constant at different orientations of the photorefractive grating vector has also been considered.

25 citations

Journal ArticleDOI
TL;DR: The photorefractive effect in BaTiO(3) crystals is extended to the 1.5-microm wavelength regime, which is obtained by two-photon absorption induced by intense femtosecond light pulses, and can be used to form optical components for communication applications.
Abstract: We demonstrate the extension of the photorefractive effect in BaTiO3 crystals to the 1.5-μm wavelength regime, which is obtained by two-photon absorption induced by intense femtosecond light pulses. The strong dependence of the effect on the light’s intensity permits nondestructive readout of the photorefractively induced pattern by low-intensity light. One can thus use the photorefractive effect in the 1.5-μm regime to form optical components for communication applications.

25 citations

Journal ArticleDOI
TL;DR: The photorefractive performance of a polymer composite sensitized by CdSe/ZnS core/shell nanoparticles, and also comprising poly(N-vinylcarbazole) and an electro-optic chromophore, constitutes a significant improvement on the performance of previous nanoparticle-sensitized photoreFractive polymer composites.
Abstract: We report the photorefractive performance of a polymer composite sensitized by CdSe∕ZnS core/shell nanoparticles, and also comprising poly(N-vinylcarbazole) and an electro-optic chromophore. The nanoparticles are characterized by absorption and photoluminescence spectroscopy, elemental analysis, transmission electron microscopy, and powder x-ray diffraction. The electro-optic response of the composite is measured independently of the photorefractive effect by transmission ellipsometry. An asymmetric two-beam coupling gain of 30.6±0.4cm−1 is obtained, confirming photorefractivity. Degenerate four-wave mixing is used to assess photorefractive performance and, at a poling field of 70Vμm−1, yields a diffraction efficiency of 4.21%±0.03%, a holographic contrast of 3.05×10−4±1×10−6, a space-charge rise time of 25±2s, and a sensitivity of 4.7×10−5±4×10−6cm3J−1. These results constitute a significant improvement on the performance of previous nanoparticle-sensitized photorefractive polymer composites.

25 citations

Book ChapterDOI
TL;DR: In this article, the photorefractive effect is fully reversible, meaning that the recorded holograms can be erased with a spatially uniform light beam, which can be reconstructed by diffracting a third laser beam on the periodic index modulation.
Abstract: Photorefractive polymers exhibit large refractive index changes when exposed to low power laser beams. When the optical excitation consists of two interfering coherent beams, the periodic light distribution produces a periodic refractive index modulation. The resulting index change produces a hologram in the volume of the polymer film. The hologram can be reconstructed by diffracting a third laser beam on the periodic index modulation. In contrast to many physical processes that can be used to generate a refractive index change, the photorefractive effect is fully reversible, meaning that the recorded holograms can be erased with a spatially uniform light beam. This reversibility makes photorefractive polymers suitable for real-time holographic applications. The mechanism that leads to the formation of a photorefractive index modulation involves the formation of an internal electric field through the absorption of light, the generation of carriers, their transport and trapping over macroscopic distances. The resulting electric field produces a refractive index change through orientational or non-linear optical effects. Due to the transport process, the index modulation amplitude is phase shifted with respect to the periodic light distribution produced by the interfering optical beams that generate the hologram. This phase shift enables the coherent energy transfer between two beams propagating in a thick photorefractive material. This property, referred to as two-beam coupling, is used to build optical amplifiers. Hence, photorefractive materials are also playing a role in imaging applications. Discovered and studied for several decades mainly in inorganic crystals and semiconductors, the photorefractive effect has not yet found wide spread commercial applications. This can be attributed to the difficulties associated with the growth of crystals, and to the high cost of optical and optomechanical components necessary for the development of complete optical systems. With the emergence of novel low cost plastic optical components that can be mass produced by techniques such as injection molding, the cost and the weight of optical components is decreasing rapidly. This trend together with the advances made in fabricating integrated laser sources at lower cost provide a great momentum to the development of new optical processing technologies. As real-time optical recording and processing media, photorefractive polymers are expected to play a major role in these technologies. The optical, physical, and chemical properties of photorefractive polymers are outlined and discussed. Current material classes and their respective merits and future challenges are presented together with examples of applications.

25 citations


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