Graded-reflectance mirrors for beam quality control in laser resonators

Abstract

Several types of small-dimension graded-reflectance mirrors deposited through rotating masks are compared. Multilayer mirrors provided with single-variable-thickness layers have limitations that are avoided when all the layers in the system are shaped. High-reflectance mirrors of the latter type are demonstrated. Numerical and experimental results are given.

Techniques for fabrication of multilayer dielectric graded-reflectivity mirrors and their use enhancement of the brightness of the radiation from a multimode Nd3+:YAG laser with a stable cavity

“…In a multilayer dielectric GM or SGM the thickness of at least one of the alternate layers (which is I/An, where X is the radiation wavelength and n is the refractive index) varies smoothly over the mirror surface (Fig. 1 rotating mask [2,3,7,18,19] and the method utilising the shadow of a cylindrical aperture located at a certain distance from an optical component [1][2][3][4][5][6][7][17][18][19] ('fixed mask' method). We used the latter method because it is simpler, does not require modification of the vacuum chamber, and permits experimental determination of the mask parameters (diameter of the cylindrical aperture and mask thickness) needed to obtain a given profile of the mirror surface reflectivity.…”

Azimuthally Varying Guided Mode Resonance Filters

“…Graded Reflectivity Mirrors (GRM) have been used in laser systems as beam quality and mode controllers, as well as output beam shapers [1,2]. The typical method of creating a spatially varying reflectance or transmittance profile is achieved by spatially varying thin dielectric film non-absorbers [3,4].…”

Spatial and spectral beam shaping with space-variant guided mode resonance filters

“…Techniques for realizing graded reflectivity mirrors are limited and depend on complicated deposition techniques [9,10]. These mirrors provide a phase shift to the reflected and transmitted beams, which may be undesirable in certain cases.…”