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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09 Jul 2001
TL;DR: In this paper, the thickness of the volume phase material and the modulation of its refractive index are jointly established to provide equalization of diffraction efficiencies for all polarizations over a wide range of wavelengths.
Abstract: An enhanced volume phase diffraction grating provides high dispersion, uniformly high diffraction efficiency and equal diffraction efficiencies for all polarizations across a wide range of wavelengths. The thickness of the volume phase material and the modulation of its refractive index are jointly established to provide equalization of diffraction efficiencies for all polarizations over a wide range of wavelengths. The equalization occurs where the S and P diffraction efficiencies are both at a maximum.
49 citations
TL;DR: The proposed FLCFZLs with simple fabrication open several opportunities to improve the quality of existing devices and to find new applications, including the diffracting element, which provides fast response time, high diffraction efficiency, and saturated electro-optical operations up to high frequency.
Abstract: In this Letter, we disclose a fast switchable Fresnel zone lens (FZL) by confining the ferroelectric liquid crystals (FLCs) in multiple microscopically defined photo-aligned alignment domains. The photo-alignment (PA) offers good control on the anchoring energy (W) by mean of irradiation doses (ID) and thus excellent alignment for FLCs. Two operational modes of the FLCFZL, i.e., FOCUS/OFF and FOCUS/DEFOCUS, were demonstrated. The proposed diffracting element provides fast response time, high diffraction efficiency (η), with saturated electro-optical (EO) operations up to high frequency (≈2 kHz). Thus, the proposed FLCFZLs with simple fabrication open several opportunities to improve the quality of existing devices and to find new applications.
49 citations
01 Apr 1992
TL;DR: In this article, the diffraction efficiency and nonlinear transmission properties of chemically enhanced thin films of bacteriorhodopsin were analyzed by using absorption spectroscopy, the Kramers-Kronig transformation, coupled wave theory, and a simplified kinetic model of the photocycle.
Abstract: The diffraction efficiency and nonlinear transmission properties of chemically enhanced thin films of bacteriorhodopsin are analyzed by using absorption spectroscopy, the Kramers-Kronig transformation, coupled wave theory, and a simplified kinetic model of the bacteriorhodopsin photocycle. Photoconversion of bR to a 50:50 mixture of bR and M generates a large change in refractive index that is proportional to the bacteriorhodopsin concentration and is greatest in regions where the difference in absorption coefficients is smallest. The predicted diffraction efficiencies are dominated by large phase components in regions of minimal bR and M absorption. The maximum diffraction efficiency (11) for a 2.5 OD, 150 micrometers thick film occurs at readout wavelengths between 620 nm - 700 nm. These films also exhibit significant nonlinearity in transmissivity at low laser intensities and could find potential use in spatial filtering applications. A real time optical associative memory based on holographic thin films of bacteriorhodopsin is also discussed.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
49 citations
TL;DR: In this article, an extended investigation made on holographic polymer dispersed liquid crystals is presented, where a spectroscopic study of the photosensitive mixtures during the polymerization and phase separation process was performed, and an optical characterization of the recorded phase gratings was carried out using two alternative methods.
Abstract: In this study we present an extended investigation made on holographic polymer dispersed liquid crystals. A spectroscopic study of the photosensitive mixtures during the polymerization and phase separation process was performed, and an optical characterization of the recorded phase gratings was carried out using two alternative methods. The behavior of the diffraction efficiency of the transmission phase gratings versus time, angle of incidence, and wavelength was experimentally determined, and the results were successfully analyzed using the available theories for anisotropic phase gratings. Finally, the electro-optical properties concerning the beam deflection and response times were measured.
49 citations
TL;DR: In this paper, the Fourier grating is introduced, which uses a smooth grating structure and can be manufactured with high precision as reflection gratings even for two-dimensional (2-D) dispersion.
Abstract: Over the past years, a number of groups have developed phase gratings as local oscillator beam multiplexers for array receivers in the submillimeter wavelength domain. The most popular type of grating is the Dammann (1977) grating, a simple and versatile binary phase grating. We introduce a new type of grating, the Fourier grating, which, in contrast to the binary structure of Dammann gratings, uses a smooth grating structure. Due to the lack of sharp edges these gratings can be manufactured with high precision as reflection gratings even for two-dimensional (2-D) dispersion. Fourier gratings are designed using a simple optimization procedure that only involves a small number of parameters. Their diffraction efficiency is very high. We have produced a number of gratings and tested them at a frequency of 490 GHz, verifying the theoretical results.
49 citations