A photorefractive polymer with high optical gain and diffraction efficiency near 100
TL;DR: In this article, the authors describe a polymer composite with excellent photorefractive properties, achieving a diffraction efficiency approaching 100% and a net two-beam coupling gain of more than 200 cm-1.
Abstract: PHOTOREFRACTIVE materials are of considerable interest for the development of all-optical devices1. The photoref ractive effect appears in materials that exhibit an electric-field-dependent refractive index and that are photosensitive, such that the spatial distribution of photogenerated charge carriers is modified on irradiation with light. The diffraction pattern formed by the interference of two coherent light beams within such a material generates a non-uniform internal electric field that in turn modulates the refractive index. The resulting refractive-index pattern forms a grating that can diffract light and thereby give rise to two-beam coupling, whereby one of the writing beams gains energy at the expense of the other—a property that can be exploited in photonic devices. Although the best photorefractive materials currently available are inorganic crystals such as LiNbO3, there is considerable interest in the development of photorefractive polymers2–8, owing to their structural flexibility, ease of processing and lower cost. We describe here a polymer composite with excellent photorefractive properties. We have achieved a diffraction efficiency approaching 100% and a net two-beam coupling gain of more than 200 cm–1, making these polymeric materials suitable for immediate application in areas such as dynamic holographic storage and optical information processing1.
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TL;DR: This critical review details the studies completed to date on the 3 main classes of azobenzene derivatives and explains the mechanism behind the isomerization mechanism.
Abstract: Azobenzene undergoes trans → cisisomerization when irradiated with light tuned to an appropriate wavelength. The reverse cis →transisomerization can be driven by light or occurs thermally in the dark. Azobenzene's photochromatic properties make it an ideal component of numerous molecular devices and functional materials. Despite the abundance of application-driven research, azobenzene photochemistry and the isomerization mechanism remain topics of investigation. Additional substituents on the azobenzene ring system change the spectroscopic properties and isomerization mechanism. This critical review details the studies completed to date on the 3 main classes of azobenzene derivatives. Understanding the differences in photochemistry, which originate from substitution, is imperative in exploiting azobenzene in the desired applications.
2,062 citations
TL;DR: The ability of nonlinear optical materials to transmit, process and store information forms the basis of emerging optoelectronic and photonic technologies as discussed by the authors, where organic chromophore-containing polymers, in which the refractive index can be controlled by light or an electric field, are expected to play an important role.
Abstract: The ability of nonlinear optical materials to transmit, process and store information forms the basis of emerging optoelectronic and photonic technologies. Organic chromophore-containing polymers, in which the refractive index can be controlled by light or an electric field, are expected to play an important role.
974 citations
Cites background from "A photorefractive polymer with high..."
...combined solely electro-optic and photoconducting properties (as in their inorganic crystalline counterparts such as LiNbO 3 ), present-day polymers show additional orientational effect...
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TL;DR: In this article, the recent progress of studies on photo-and electroactive amorphous molecular materials, highlighting photochromic amorphus molecular materials and their use in organic EL devices is discussed.
Abstract: A new field of organic materials science that deals with amorphous molecular glasses has been opened up. In addition, amorphous molecular materials have constituted a new class of functional organic materials for use in various applications. This article is focused on the recent progress of studies on photo- and electroactive amorphous molecular materials, highlighting photochromic amorphous molecular materials, amorphous molecular resists, and amorphous molecular materials for use in devices such as organic EL devices. The molecular design concepts, syntheses, reactions, molecular and solid-state properties, functions, and device fabrication and performance are described.
883 citations
TL;DR: The synthesis and properties of carbazole-containing polymers are reviewed with 451 references in this paper, including polymers with pendant carbazolyl groups, polymers containing electronically isolated carbonazole moieties in the main chain, polymer with π-conjugated main chain and polymers as well as carbazoleside-containing molecular glasses.
702 citations
TL;DR: Two types of photomodulation of orientations of liquid crystals (LCs) are reviewed: 1) order-disorder phase transitions induced by photochemical reactions of photochromic molecules and 2) orderorder alignment change of LCs (change in LC directors) induced by photoochemical reactions or without photochemical events.
Abstract: Two types of photomodulation of orientations of liquid crystals (LCs) are reviewed: 1) order–disorder phase transitions of LCs induced by photochemical reactions of photochromic molecules and 2) order–order alignment change of LCs (change in LC directors) induced by photochemical reactions or without photochemical events. Both processes produce a large refractive-index modulation, which forms the basis of a range of photonic applications. Various modes of photomodulation of orientations of LCs with plausible mechanisms and their possible applications in photonics are described.
688 citations
References
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TL;DR: In this paper, a coupled wave analysis of the Bragg diffraction of light by thick hologram gratings is given, analogous to Phariseau's treatment of acoustic gratings and to the dynamical theory of X-ray diffraction.
Abstract: A coupled wave analysis is given of the Bragg diffraction of light by thick hologram gratings, which is analogous to Phariseau's treatment of acoustic gratings and to the “dynamical” theory of X-ray diffraction. The theory remains valid for large diffraction efficiencies where the incident wave is strongly depleted. It is applied to transmission holograms and to reflection holograms. Spatial modulations of both the refractive index and the absorption constant are allowed for. The effects of loss in the grating and of slanted fringes are also considered. Algebraic formulas and their numerical evaluations are given for the diffraction efficiencies and the angular and wavelength sensitivities of the various hologram types.
5,244 citations
TL;DR: In this paper, a non-linear theory of self-diffraction on the light induced grating of refractive index in electrooptic crystals is developed and the intensities of the diffracted beams, the diffraction efficiency, and the shape of the surfaces of equal index change are calculated analytically for saturation holograms.
Abstract: The non-linear theory of the self-diffraction on the light induced grating of refractive index in electrooptic crystals is developed. The intensities of the diffracted beams, the diffraction efficiency, and the shape of the surfaces of equal index change are calculated analytically for saturation holograms.Holographic storage in nominally pure reduced crystals of LiNbO3 is studied experimentally. It is shown that the developed theory in diffusion approximation satisfactorily describes the experimental data.
1,537 citations
Journal Article•
TL;DR: This is the first volume of a set of three within the Springer Series in Optical Sciences, and is devoted to photorefractive effects, photoreFractive materials, and their applications.
Abstract: This is the first volume of a set of three within the Springer Series in Optical Sciences, and is devoted to photorefractive effects, photorefractive materials, and their applications. Since the publication of our first two Springer books on Photorefractive Materials and Their Applications (Topics in Applied Physics, Vols. 61 and 62) almost 20 years ago, a lot of research has been done in this area. New and often expected effects have been discovered, theoretical models developed, known effects finally explained, and novel applications proposed. We believe that the field has now reached a high level of maturity, even if research continues in all areas mentioned above and with new discoveries arriving quite regularly. We therefore have decided to invite some of the top experts in the field to put together the state of the art in their respective fields. This after we had been encouraged to do so for more than ten years by the publisher, due to the fact that the former volumes were long out of print.
1,154 citations
IBM1
TL;DR: The observation of the photorefractive effect in an amorphous electro-optic material, the nonlinear polymer bisphenol A diglycidyl ether 4-nitro-1,2,phenylenediamine (bisA-NPDA) make photoconductive by doping with the hole transport agent diethylaminobenzaldehyde-diphenyl hydrazone.
Abstract: We report the first observation of the photorefractive effect in a polymeric material, the electro-optic polymer bisphenol-A-diglycidylether 4-nitro-1,2-phenylenediamine made photoconductive by doping with the hole-transport agent diethylamino-benzaldehyde diphenylhydrazone. The gratings formed exhibit dynamic writing and erasure, strong electric-field dependence, polarization anisotropy, and estimated space-charge fields up to 26 kV/cm at an applied field of 126 kV/cm. Application of similar concepts should provide a broad new class of easily fabricated photorefractive materials.
572 citations