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: Transient and persistent holographic gratings have been observed in dye- and fullerene C(60)-doped nematic liquid-crystal films and the nature and time evolution of the underlying mechanisms, such as space-charge field production, flows, and dielectric- and conductivity-induced torques are examined.
Abstract: Transient and persistent holographic gratings have been observed in dye- and fullerene C60-doped nematic liquid-crystal films. The nature and time evolution of the underlying mechanisms, such as space-charge field production, flows, and dielectric- and conductivity-induced torques, and the resultant director axis reorientation and refractive-index gratings are examined.
171 citations
TL;DR: In this article, a simple formula for the threshold wavelength of total internal reflection was derived for amorphous hydrogenated silicon (a-Si:H) solar cells using periodically structured aluminum doped zinc oxide (ZnO:Al) with periods between 390 and 980 nm as a transparent front contact.
Abstract: Efficient light trapping structures for amorphous hydrogenated silicon (a-Si:H) solar cells have been realized using periodically structured aluminum doped zinc oxide (ZnO:Al) with periods between 390 and 980 nm as a transparent front contact. Atomic force microscopy, optical reflection, and diffraction efficiency measurements were applied to characterize solar cells deposited on such gratings. A simple formula for the threshold wavelength of total internal reflection is derived. Periodic light coupler gratings reduce the reflectance to a value below 10% in the wavelength range of 400–800 nm which is comparable to cells with an optimized statistical texture. Diffraction efficiency measurements and theoretical considerations indicate that a combination of transmission and reflection gratings contribute to the observed reduction of the reflectance.
171 citations
TL;DR: It is shown that polarization holography may be used for real-time simultaneous measurement of photoinduced linear and circular birefringence in thin phase polarization holographic gratings recorded with two waves with orthogonal linear polarizations in materials in which illumination with linearly/ Circularly polarized light gives rise to linear/circular bireFringence.
Abstract: We investigate thin phase polarization holographic gratings recorded with two waves with orthogonal linear polarizations in materials in which illumination with linearly/circularly polarized light gives rise to linear/circular birefringence. The theoretical analysis shows that the presence of circular photoanisotropy changes significantly the diffraction characteristics of the gratings. The intensities of the waves diffracted in the +1 and −1 orders of diffraction and their ratio depend substantially on the reconstructing-wave polarization. Experiments with films of side-chain liquid-crystalline azobenzene polyester that is a photoanisotropic material of the considered type confirm the unusual polarization properties. It is shown that polarization holography may be used for real-time simultaneous measurement of photoinduced linear and circular birefringence.
167 citations
TL;DR: A blazing technique using electron-beam lithography to achieve higher efficiency of gratings and Fresnel lenses is described, and the experimental results showed high-efficiency performance and nearly diffraction-limited focusing.
Abstract: A blazing technique using electron-beam lithography to achieve higher efficiency of gratings and Fresnel lenses is described. Transmission-type blazed gratings have been formed in polymethyl methacrylate films. As a result of measurement, we found that their diffraction efficiency of the first order in these gratings amounts to as much as 60 to 70% at 0.633 microm. Fresnel lenses of 1-mm diameter and 5-mm focal length, which have a sawtooth relief profile, have been also fabricated, and the experimental results showed high-efficiency performance (about 50%) and nearly diffraction-limited focusing.
166 citations
TL;DR: In this paper, a new rigorous integral formalism for the theoretical study of dielectric coated gratings and grating couplers is presented, which applies in the resonance domain, where the wavelength of the incident field and the groove spacing are of the same order of magnitude.
Abstract: We present a new rigorous integral formalism for the theoretical study of dielectric coated gratings and grating couplers. It applies in the resonance domain, where the wavelength of the incident field and the groove spacing are of the same order of magnitude. The computed program issued from this theory extends the domain of application of the previous differential or integral theories. It can be used to investigate, with a very good accuracy, the properties of bare or dielectric coated gratings, for any groove shape and any polarization, in the entire visible, ultraviolet, and infrared regions. Various classical criteria are used to control the validity of the numerical results and comparisons are made with the numerical results obtained using the previous integral and differential formalisms. Two examples of applications are given. First, we show that the new possibilities of our program lead to a better agreement between theoretical results and experimental data. Second, a theoretical study of a certain type of grating coupler is given.
163 citations