Diffraction efficiency

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

Optical vortices generated by dislocations in a cholesteric liquid crystal.

Abstract: We report the observation of optical vortices in a laser beam propagating through the stripe pattern of a cholesteric liquid crystal. The liquid crystal is confined in a cell with homogeneous boundary conditions and forms a diffraction phase grating. Optical vortices are produced by edge dislocations of the cholesteric grating. The vortices show up as spots of zero light intensity in the diffraction maxima. There is one spot in each +1 and -1 diffraction maximum and two spots in diffraction maxima +2 and -2.

Fabrication and testing of chemically micromachined silicon echelle gratings.

Abstract: We have fabricated large, coarsely ruled, echelle patterns on silicon wafers by using photolithography and chemical-etching techniques. The grating patterns consist of 142-µm-wide, V-shaped grooves with an opening angle of 70.6°, blazed at 54.7°. We present a detailed description of our grating-fabrication techniques and the results of extensive testing. We have measured peak diffraction efficiencies of 70% at λ = 632.8 nm and conclude that the gratings produced by our method are of sufficient quality for use in high-resolution spectrographs in the visible and near IR (λ ≃ 500–5000 nm).

High-efficiency continuous surface-relief gratings for two-dimensional array generation.

Abstract: Continuous surface-relief phase gratings for two-dimensional (2-D) array generation have been realized by laser-beam writing lithography For a 9 × 9 fan-out element, a diffraction efficiency of 94% and a uniformity of better than ±8% have been achieved These are, to our knowledge, the best published results for 2-D surface-relief fan-out elements Separable and nonseparable solutions for the design of 2-D fan-out elements are discussed

Blazed high-efficiency x-ray diffraction via transmission through arrays of nanometer-scale mirrors

Abstract: Diffraction gratings are ubiquitous wavelength dispersive elements for photons as well as for subatomic particles, atoms, and large molecules. They serve as enabling devices for spectroscopy, microscopy, and interferometry in numerous applications across the physical sciences. Transmission gratings are required in applications that demand high alignment and figure error tolerances, low weight and size, or a straight-through zero-order beam. However, photons or particles are often strongly absorbed upon transmission, e.g., in the increasingly important extreme ultraviolet (EUV) and soft x-ray band, leading to low diffraction efficiency. We demonstrate the performance of a critical-angle transmission (CAT) grating in the EUV and soft x-ray band that for the first time combines the advantages of transmission gratings with the superior broadband efficiency of blazed reflection gratings via reflection from nanofabricated periodic arrays of atomically smooth nanometer-thin silicon mirrors at angles below the critical angle for total external reflection. The efficiency of the CAT grating design is not limited to photons, but also opens the door to new, sensitive, and compact experiments and applications in atom and neutron optics, as well as for the efficient diffraction of electrons, ions, or molecules.

Generation of rotating gauss—Laguerre modes with binary-phase diffractive optics

Abstract: We demonstrate the rotation of multimodel Gauss—Laguerre beams generated with a binary-phase diffractive element. The element is designed with the use of an iterative procedure and quantized in two levels after adding a carrier frequency to the phase. The fabrication technology of the diffractive element involves e-beam lithography and reactive ion etching. Experimental and theoretical results are shown to be in good conformity.