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Diffraction efficiency
About: Diffraction efficiency is a research topic. Over the lifetime, 10320 publications have been published within this topic receiving 158298 citations.
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TL;DR: In this paper, the authors report on a high optical quality, long-life guest-host photorefractive polymer composite which exhibits a 60% device steadystate diffraction efficiency and 120 cm−1 two-beam coupling gain, well in excess of its absorption of 3.5 cm− 1, at a wavelength of 676 nm.
Abstract: We report on a high optical quality, long‐life guest‐host photorefractive polymer composite which exhibits a 60% device steady‐state diffraction efficiency and 120 cm−1 two‐beam coupling gain, well in excess of its absorption of 3.5 cm−1, at a wavelength of 676 nm. In contrast to alternative composite materials of comparable high dye content, this performance has been achieved without unacceptably compromising device lifetime or ease of fabrication and storage. This is an efficient, easily prepared and comparatively stable polymer composite with device lifetimes under storage conditions already exceeding eight months and no indication of sample degradation with repeated holographic read–write cycles.
88 citations
TL;DR: In this article, the authors developed a phenomenological model of grating formation that incorporates the photophysics and photochemistry of the initiator dye, reaction-diffusion kinetics of the monomer-polymer system, phase separation of the liquid crystal, nematic order evolution of liquid-crystal droplets, and volume shrinkage of the polymer.
Abstract: The real time formation of anisotropic volume holographic reflection gratings in a liquid-crystal/photopolymer mixture is studied. We develop a phenomenological model of grating formation that incorporates the photophysics and photochemistry of the initiator dye, reaction-diffusion kinetics of the monomer-polymer system, phase separation of the liquid crystal, nematic order evolution of liquid-crystal droplets, and volume shrinkage of the polymer. We then test this model by experimentally monitoring the diffraction efficiency for s and p polarization, Bragg wavelength, and laser scattering in real time as the grating is formed. The model yields good agreement with experimental data for different recording intensities and exposure times. We discuss the physics of the system as it evolves in time and explain the major features of anisotropic grating formation in acrylate-based holographic polymer-dispersed liquid crystals.
88 citations
TL;DR: In this article, the diffraction efficiency, birefringence, and surface relief modulation were investigated on functionalized azopolymer films of p(DR1M-co-MMA) with a 12% mole fraction of DR1M.
Abstract: Dynamical experimental studies of the diffraction efficiency, birefringence, and surface relief modulation were carried out on functionalized azopolymer films of p(DR1M-co-MMA) with a 12% mole fraction of DR1M The gratings were recorded using two linearly polarized pump beams (λ = 5145 nm) either with a parallel configuration (p+p) or (s+(-s)) or with orthogonal polarizations (p+s) A general Jones matricial approach in conjuction with real-time polarization analyses of the first order diffracted beam (S+1) appears to be a quite sensitive method to extract relevant parameters such as birefringence (Δn) and surface relief modulation (2Δd) The phase matrices have been developed considering the pump polarization of the two interfering beams and taking into account the orientational “angular hole-burning” model under low pump irradiances Numerical calculations allow us to extract the time variations of Δn and 2Δd and to compare the various efficiencies in grating formation The obtained values for Δn are
88 citations
TL;DR: In this article, a continuous surface-relief diffractive optical element for two-dimensional array generation (fan-out) is designed and fabricated, and the phase-grating microstructures are generated by laser-beam writing lithography in a single exposure step and converted to nickel shims by electroplating.
Abstract: Continuous surface-relief diffractive optical elements for two-dimensional array generation (fan-out) are designed and fabricated. Separable and nonseparable solutions for the two-dimensional element design are compared. The phase-grating microstructures are generated by laser-beam writing lithography in a single exposure step and converted to nickel shims by electroplating, enabling low-cost replicas to be produced by using laboratory and commercial replication processes. Results are presented for a 9 x 9 fan-out diffractive optical element with a measured efficiency of 94% and an overall uniformity within +/-8%; replicas in epoxy have the same efficiency and a uniformity of +/-15%.
88 citations
TL;DR: Electrical control of holographic diffraction efficiency in PLZT ceramics and electrical fixation and erasure of holograms recorded in SBN single crystals are reported.
Abstract: After defining photoferroelectrics as photosensitive and nonlinear electrooptic materials, we report electrical control of holographic diffraction efficiency in PLZT ceramics and electrical fixation and erasure of holograms recorded in SBN single crystals On the basis of experimental data, these effects are explained in terms of the local field amplitude, computed as the sum of the applied field and the photoinduced space charge field and high nonlinear electrooptic effects associated with ferroelectric phase transitions
87 citations