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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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Journal ArticleDOI
TL;DR: In this article, the authors investigate the properties of finite-aperture waveguide-grating resonance filters by means of rigorous electromagnetic theory and an approximate model, and provide an optical-engineering model for the estimation of the minimum grating size required to achieve a high resonance-wavelength reflectivity.
Abstract: The operation of optical narrowband reflection filters based on resonance anomalies of waveguide gratings is well established for gratings of infinite extent. We investigate the properties of finite-aperture waveguide-grating resonance filters by means of rigorous electromagnetic theory and an approximate model. The rigorous approach illustrates the scattering of optical energy from the guided mode at and near the edges of the element, which leads to a reduced diffraction efficiency into the backward-diffracted zeroth order. The approximate approach provides an optical-engineering model for the estimation of the minimum grating size required to achieve a high resonance-wavelength reflectivity.

59 citations

Journal ArticleDOI
TL;DR: In this article, a review on the diffraction of electromagnetic waves is presented, focusing on the ways to overcome beam divergence and diffraction limit, including apodization techniques to reduce the divergence of a laser beam and increase the resolution.
Abstract: Diffraction is a natural phenomenon, which occurs when waves propagate or encounter an obstacle. Diffraction is also a fundamental aspect of modern optics: all imaging systems are diffraction systems. However, like a coin has two sides, diffraction also leads to some unfavorable effects, such as an increase in the size of a beam during propagation, and a limited minimal beam size after focusing. To overcome these disadvantages set by diffraction, many techniques have been developed by various groups, including apodization techniques to reduce the divergence of a laser beam and increase the resolution, and time reversal, STED microscopy, super lenses and optical antennas to obtain resolution down to nano-scale. This review concentrates on the diffraction of electromagnetic waves, and the ways to overcome beam divergence and the diffraction limit.

59 citations

Journal ArticleDOI
TL;DR: A high-efficiency grating is made by coating a nine-layer quarter-wave system of ZnS/Na(3)AlF(6) directly onto a surface-relief grating in photoresist in qualitative agreement with theoretical predictions.
Abstract: We made a high-efficiency reflection grating by coating a nine-layer quarter-wave system of ZnS/Na3AlF6 directly onto a surface-relief grating in photoresist. Efficiencies of 70% and 84% were measured at the first-order Littrow mount with the laser beam incident from the air side and from the substrate side, respectively. The experimental results are in qualitative agreement with theoretical predictions. The key to further improvement in the diffraction efficiency is to improve the contour conformation of the coated dielectric layers.

59 citations

Journal ArticleDOI
TL;DR: In this article, a one-dimensional reflection grating structure was fabricated by patterning a semicrystalline polymer, polyethylene glycol (PEG), in Norland resin (thiol-ene based UV curable resin) matrix using the holographic photopolymerization (H-P) technique.
Abstract: Holographic photopolymerization (H-P) is a simple, fast and attractive means to fabricate one-, two- and three-dimensional complex structures. Liquid crystals, nanoparticles and silicate nano-plates have been patterned into submicron periodical structures. In this article, we report fabrication of a one-dimensional reflection grating structure by patterning a semicrystalline polymer, polyethylene glycol (PEG), in Norland resin (thiol-ene based UV curable resin) matrix using the H-P technique. Sharp notches observed in the reflection grating of this Norland/PEG system indicate a finite Δn present in the system due to spatial segregation of the PEG and Norland resin. The notch position red shifts upon heating and the diffraction efficiency (ratio between diffraction and incident light intensity, DE) increases from ∼20% to 60% for the Norland 65/PEG 4600 grating. This dynamic behavior of the reflection grating is also fully reversible. The unique thermal switching behavior is attributed to the melting/formation of PEG crystals during heating/cooling. By employing different molecular weight PEGs which have different melting temperatures, a series of switching temperatures have been achieved. Since PEG can be easily coupled with a variety of functional groups, this research might shed light on fabricating multifunctional Bragg gratings using the H-P technique.

58 citations

Journal ArticleDOI
TL;DR: Scalar diffraction theory and electromagnetic vector theory are compared by analyzing plane-wave scattering by a perfectly conducting, rectangular-grooved grating and one general conclusion is that, depending on polarization, scalar theory should not be used when the grating period becomes smaller than ten wavelengths.
Abstract: Scalar diffraction theory and electromagnetic vector theory are compared by analyzing plane-wave scattering by a perfectly conducting, rectangular-grooved grating. General field solutions for arbitrary angles of incidence are derived by using scalar and vector theories. Diffraction efficiencies for the scalar and the vector cases as functions of wavelength, grating period, and angles of incidence are determined numerically and plotted. When the wavelength of the incident field is much shorter than the grating period, the diffraction efficiencies match. But when the wavelength is of the order of the grating period, large differences between the scalar and the vector solutions emerge. One general conclusion is that, depending on polarization, scalar theory should not be used when the grating period becomes smaller than ten wavelengths.

58 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202391
2022188
2021167
2020223
2019259
2018259