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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Papers
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TL;DR: It is shown that paraxial designs are not adequate for f/Nos.
Abstract: The optical properties of holographic kinoforms are described. It is shown that paraxial designs are not adequate for f /Nos. less than ~F/10. A nonparaxial design is introduced that retains the high diffraction efficiency of the paraxial designs, yet also produces an unaberrated diffracted wavefront for the design wavelength. Aberration calculations and computer calculations, based on the Huygens-Fresnel principle, of the point spread functions for these elements show the necessity of using the nonparaxial design. Specifications for a surface profile that takes account of the finite thickness of the diffracting surface are given. A model for kinoforms which can be used in optical design programs is proposed.
176 citations
TL;DR: An experimental demonstration of a normal-incidence guided-mode resonant silicon grating upon a sapphire substrate and the measured reflection resonance had a FWHM of 67-100 nm for angles of incidence of 0-8 degrees and peak efficiency of ~80% .
Abstract: Guided-mode resonant grating filters have numerous applications. However, in weakly modulated gratings designed for use at normal incidence, the filtering resonance of these subwavelength-period devices splits for angles of incidence that are even slightly off normal incidence. Strongly modulated gratings are designed that essentially overcome this practical problem near normal incidence. In addition, these gratings can have, by design, either broad or narrow spectral characteristics. An experimental demonstration (1.5-2.0-mu m wavelength range) of such a normal-incidence guided-mode resonant silicon grating upon a sapphire substrate is presented. The measured reflection resonance had a FWHM of 67-100 nm for angles of incidence of 0-8 degrees and peak efficiency of ~80% .
175 citations
TL;DR: In this article, a set of coupled-wave equations that characterize the Bragg regime has been derived for the 〈110〉 and the ¾¾ ¾ crystallographic orientations typically employed in volume holographic storage and multi-wave-mixing applications.
Abstract: The polarization properties of diffraction from volume phase gratings in photorefractive sillenite crystals such as bismuth silicon oxide (Bi12SiO20), bismuth germanium oxide (Bi12GeO20), and bismuth titanium oxide (Bi12TiO20) are strongly modified by the presence of concomitant natural optical activity and electric-field-induced linear birefringence. A set of coupled-wave equations that characterize the Bragg regime has been derived for the 〈110〉 and the 〈001〉 crystallographic orientations typically employed in volume holographic storage and multiwave-mixing applications. The predicted anisotropic behavior of the grating diffraction is experimentally confirmed, and a significant efficiency improvement is shown to occur for proper choice of the operating mode and the probe beam polarization in a given configuration.
174 citations
TL;DR: Using rigorous coupled-wave analysis, high spatial-frequency rectangular-groove surface-relief phase gratings are shown to be capable of exhibiting zero reflectivity, and these corrugated surfaces may act as antireflection coatings in a variety of applications.
Abstract: Using rigorous coupled-wave analysis, high spatial-frequency rectangular-groove surface-relief phase gratings are shown to be capable of exhibiting zero reflectivity. Thus these corrugated surfaces may act as antireflection coatings in a variety of applications. The diffraction characteristics of rectangular-groove surface-relief gratings are presented for several ratios of incident wavelength to grating period as a function of filling factor, groove depth, angle of incidence, and polarization. The conditions for zero reflectivity are identified. Results are compared with single-homogeneous-layer approximate theory results. In the limit of long wavelengths for an electromagnetic wave in a dielectric of refractive index n1 normally incident on a dielectric of index n2, it is determined that for antireflection behavior, the grating groove depth should be λ/4(n1n2)1/2 and the filling factor should be n1/(n1 + n2) or n2/(n1 + n2) for the electric field perpendicular or parallel to the grating vector, respectively. The spectral and angular responses of these gratings are like those of single-homogeneous-layer antireflection coatings. These gratings also exhibit birefringent retardation.
174 citations
TL;DR: In this paper, the diffraction efficiency and energy transfer in photorefractive Bi12SiO20 (BSO) crystals were investigated and the optimum crystallographic orientation for each effect was determined for vertical polarization of the recording beams.
Abstract: The diffraction efficiency and energy transfer are investigated in photorefractive Bi12SiO20 crystals (BSO). Dependence on fringe spacing, electric fields, light intensity and rise-time constants are reported. The optimum crystallographic orientation for each effect is determined for vertical polarization of the recording beams. It is shown that beam coupling is a very sensitive phenomenon in BSO crystals where charge transport lengths are equivalent to usual fringe spacings. Experimental results are interpreted on the basis of the nonlinear theory of self-diffraction developed by Kukhtarev et al. [10].
174 citations