Diffraction grating

About: Diffraction grating is a research topic. Over the lifetime, 24884 publications have been published within this topic receiving 372437 citations. The topic is also known as: grating.

Hard-X-ray phase-difference microscopy using a fresnel zone plate and a transmission grating.

Abstract: Novel hard x-ray phase imaging microscopy that simply uses an objective and a transmission grating is described. The microscope generated an image that exhibited twin features of a sample with an opposite phase contrast having a separation of a specific distance. Furthermore, the twin features were processed to generate an image mapping the x-ray phase shift through a simple algorithm. The presence of the grating did not degrade the spatial resolution of the microscope. The sensitivity of our microscope to light elements was about 2 orders of magnitude higher than that of the absorption contrast microscope that was attained by simply removing the grating. Our method is attractive for easily appending a quantitative phase-sensitive mode to normal x-ray microscopies, and it has potentially broad applications in biology and material sciences.

New diffraction grating pair with very linear dispersion for laser pulse compression

Abstract: The principle of operation of a new diffraction grating pair for laser pulse compression is described. This device, which exhibits a very linear group time delay variation against frequency around an inflection point, could be useful for very wide bandwidth laser pulse compression or very large compression ratios.

Rotatable Diffraction Gratings Based on Cholesteric Liquid Crystals with Phototunable Helix Pitch

Abstract: A novel type of rotatable diffraction volume gratings based on cholesteric liquid crystals with phototunable helix pitch is elaborated. For this purpose the cholesteric liquid crystalline mixture with high helix pitch tunability and reversible photoinduced helix handedness inversion containing azobenzene-derivative of the chiral-photochromic dopant is developed. It was shown that the prepared cholesteric mixture under the hybrid (homeotropic – planar) boundary conditions spontaneously forms a well-oriented striped domain texture which acts as a phase grating. Under the effect of light the changes of helix pitch take place due to the molecular photoreaction of chiral-photochromic dopant causing the variation of the period of striped domain structure and its rotation. The clockwise and counterclockwise rotation of the obtained gratings can be achieved by switching between UV and visible light, correspondingly. The maximum angle of the continuous rotation is ≈690°, while the total rotation caused by UV light illumination reaches ≈1220°. The creation of a variety of complex-organized structures by local light exposure of the cholesteric domain texture is demonstrated. The observed advanced photooptical effects have potentially wide and important applications from scientific and applied points of view.

Widely tunable monolithically integrated all-optical wavelength converters in InP

Abstract: Design, fabrication, and characterization of monolithically integrated widely tunable all-optical wavelength converters in InP is reported. The devices are based on the SGDBR laser integrated with different MZI-SOA wavelength converters. Error-free wavelength conversion at 2.5 Gbps was demonstrated over 50 nm input and 22 nm output wavelength range. Static operation, extinction ratio enhancement, signal reamplification, dynamic range, and chirp properties were characterized as well.

Optical spectrophotometer having a multi-element light source

Abstract: A spectrophotometer (10) includes an array of light emitting diodes (12) configured for activation in successive Hadamard encodement patterns, a diffraction grating (14), an optical slit (16), a detector (18) and electronic controls including a computer. In operation, the diffraction grating (14) disperses and collimates radiation from the array (12) and directs selected spectral components through the slit (16) onto the detector (18) whereupon the computer performs a Hadamard analysis on the detector signals.