Topic
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 article, the erasure time constant as a function of readout beam power, diffraction efficiency, and incident reference angle were investigated for real-time holographic recording in an iron-doped lithium niobate fiber with a 200 μm diameter and 3 mm length.
Abstract: Holographic recording on a real‐time basis of two‐dimensional images in an iron‐doped lithium niobate fiber with a 200 μm diameter and 3 mm length is demonstrated for the first time. The erasure time constant as a function of readout beam power, the diffraction efficiency as a function of incident reference angle, and the results of angular‐multiple recording of two images are shown. These results suggest that the LN fiber could replace bulk materials for holographic recordings in optical parallel processing.
43 citations
TL;DR: The experimental results showed that, compared with the other tested polarization relations during holographic recording, the discrimination between the polarization states of diffracted and scattered light is optimized with orthogonal circular polarization of the recording beams, and thus a high signal-to-noise ratio and a high diffraction efficiency are obtained.
Abstract: Optical films containing the genetic variant bacteriorhodopsin BR-D96N were experimentally studied in view of their properties as media for holographic storage. Different polarization recording schemes were tested and compared. The influence of the polarization states of the recording and readout waves on the retrieved diffractive image’s intensity and its signal-to-noise ratio were analyzed. The experimental results showed that, compared with the other tested polarization relations during holographic recording, the discrimination between the polarization states of diffracted and scattered light is optimized with orthogonal circular polarization of the recording beams, and thus a high signal-to-noise ratio and a high diffraction efficiency are obtained. Using a He–Ne laser (633 nm, 3 mW) for recording and readout, a spatial light modulator as a data input element, and a 2D-CCD sensor for data capture in a Fourier-transform holographic setup, a storage density of 2 × 108 bits/cm was obtained on a 60 × 42 µm2 area in the BR-D96N film. The readout of encoded binary data was possible with a zero-error rate at the tested storage density.
43 citations
TL;DR: In this paper, the diffraction efficiency of a fused silica fiber containing fiber Bragg gratings (FBGs) was found to fluctuate with temperature between 2.01 −10 − 4 and 0.17 − 10 − 4 with sub-Angstrom precision.
43 citations
TL;DR: Experimental results are presented which show that the diffraction efficiency and scattering obtained with such a bleach as well as its mode of operation depend very much on the choice of the alkali halide added to the bleach and its concentration.
Abstract: The use of a rehalogenating bleach without fixing to produce photographic phase holograms has been advocated on the grounds that emulsion shrinkage is minimized. It has also been reported that high diffraction efficiencies can be obtained with low scattering. Experimental results are presented which show that the diffraction efficiency and scattering obtained with such a bleach as well as its mode of operation depend very much on the choice of the alkali halide added to the bleach and its concentration. The processes responsible for the effects observed are discussed.
43 citations
TL;DR: In this article, the first-order diffraction efficiency reached to a maximum value within several tens of milliseconds: the rise time was approximately 50 ms for PM6AB2 films and 30 ms for PA6ABCN films.
Abstract: Dynamic holographic gratings were investigated with thin films of polymer azobenzene liquid crystals by periodic induction of photochemical nematic-to-isotropic phase transition. On irradiation of writing beams (488 nm), multiple diffraction beams of a reading beam (633 nm) were immediately observed. The first-order diffraction efficiency reached to a maximum value within several tens of milliseconds: the rise time was approximately 50 ms for PM6AB2 films and 30 ms for PA6ABCN films. Quite large modulation in refractive index (∼0.08) was obtained in both polymer films. Studies on effects of temperature and light intensity on the grating formation suggested that photochemical reactions of azobenzene moieties followed by photochemical phase transition in bright fringes of the interference pattern would be responsible for the formation of holographic gratings. By turning on and off the writing beams, the diffraction beams could be switched dynamically without significant fatigue.
43 citations