Diffraction efficiency

About: Diffraction efficiency is a research topic. Over the lifetime, 10320 publications have been published within this topic receiving 158298 citations.

Diffractive optical element and optical head using the same

Abstract: A diffractive optical element emits substantially zero order diffracted light when light with a wavelength of 0.35 μm to 0.45 μm is incident and emits substantially first-order diffracted light when light with a wavelength of 0.6 μm to 0.7 μm is incident. The diffractive optical element includes a substrate and a grating portion formed on the substrate. The grating portion has a step-wise cross section with any one of levels selected from four levels, five levels and six levels. The diffractive optical element emits substantially zero-order diffracted light when light with a first wavelength λ1 satisfying the relationship: 0.35 μm≦λ1≦0.45 μm is incident and emits substantially first-order diffracted light when light with a second wavelength λ2 satisfying the relationship: 0.6 μm≦λ2≦0.7 μm is incident.

Diffraction Efficiency and Angular Selectivity of Volume Phase Holograms Recorded in Photorefractive Materials

Abstract: The recording and replay of volume phase gratings in photorefractive crystals is investigated for both transmission and reflection geometries. Differential equations are derived and solved for a range of parameters including the length of the crystal, the magnitude, spatial distribution and phase angle of the refractive index modulation, the beam ratio at recording, and the angular range at replay. The recording process is assumed to reach a steady-state limit before replay with a weak probe beam. Solution of the repaly equations is mainly by numerical integration, although analytic solutions are derived for special cases. It is found that in certain cases the diffraction efficiency can be greatly increased by replaying the hologram at an angle different from the recording angle.

1‐to‐12 surface normal three‐dimensional optical interconnects

Abstract: We present a surface normal optical interconnect with a 1‐to‐12 collinear fan‐out. Two types of polymer‐based holograms were fabricated to provide a collinear 1‐to‐12 fan‐out from guided mode to substrate modes and twelve 1‐to‐1 surface normal interconnects. Fluctuation of up to 7.2 dB for the 1‐to‐12 fan‐out hologram was observed due to the oscillating and the film saturation effects of the transmission hologram. Diffraction efficiency better than 70% was observed for all the total internal reflection holograms. The result reported herein greatly enhanced optical signal processing capability of guided wave optical interconnects. The advantages of free space optical interconnect, such as global interconnect, three dimension, massive fan‐out/fan‐in capabilities, and surface normal optical interconnect, can be realized using the demonstrated architecture. The coupling from waveguide to fiber can be realized from the surface rather than the edge of a photonic integrated circuit.

Photonic crystal diffraction gratings.

Abstract: It is shown from numerical results deduced from a rigorous theory of diffraction that diffraction gratings made with two-dimensional dielectric photonic crystals may present blazing effects. Since these structures are lossless, efficiencies of 100% in the -1st order can be obtained in polarized light. Efficiency curves in Littrow mount are shown.

Fabrication and characterization of diffraction gratings using photosensitive al2o3 gel films

Abstract: A new process for the fabrication of diffraction gratings has been proposed using photosensitive Al2O3 gel films in combination with a phase mask. Photosensitive Al2O3 gel films were derived from Al(O-sec-Bu)3 chemically modified with benzoylacetone. These gel films exhibited an optical absorption band in the UV-range, which is associated with the π–π* transition of chelate rings of the β-diketonate ligand. The irradiation of these gel films with XeF and KrF excimer lasers decreased their solubility in acetone containing 1.2 vol%HNO3, simultaneously with the dissociation of the remaining chelate rings. The above findings were applied to the fabrication of Al2O3 film diffraction gratings on Si and silica substrates; the gel films were irradiated with the excimer lasers through a phase mask, leached, and then heat-treated. The diffraction efficiency of the fabricated gratings was evaluated in reflection (Si sub.) and transmission (silica sub.) modes with respect to the preparation conditions.