Band elimination filter

Abstract

The invention relates to a band elimination filter applied to incident light conforming to a Bragg condition. The band elimination filter comprises at least one block Bragg grating, wherein the blockBragg grating is used for diffracting the incident and outputting transmission light. The band elimination filter has the following advantages that 1, wavefront distortion suppression of special medium and high frequencies in a non-focusing mode is achieved, the band elimination filter is compact in structure and small in space volume, and a non-linear effect such as small scale and automatic focusing can be effectively prevented in high-power laser application; 2, a laser-induced damage threshold is high, and the energy density of 10J / cm<2> can be borne; 3, since the Bragg gratings with different structural parameters can be selectively used, function parameters (refractive index modulation degree, band elimination filtering efficiency, band elimination filtering bandwidth and band elimination filtering characteristic frequency) all can be tuned; and 4, on the basis that an optical axis of input-output light beam of the block Bragg grating is not changed, the band elimination filter can achieve plug-and-play function in a high-power laser system.

Description

technical field [0001] The invention relates to a band rejection filter. Background technique [0002] In a high power laser system, when the light intensity reaches 5×10 9 W / cm 2 , nonlinear effects in optical components cannot be ignored. Damage spots, stains, optical inhomogeneities, and dust in the optical path on the surface and interior of optical components will inevitably cause the beam to receive spatial modulation, including amplitude modulation and phase modulation. Classified according to the spatial scale, the spatial modulation is mainly divided into four areas: figure area, waviness-I area, waviness-II area, and roughness area. The figure area is the low frequency area, and the waviness-I and waviness-II areas are medium and high frequency areas. The roughness area is a high frequency area. The medium and high frequency components in the waviness-I area determine the focal spot distribution after the beam is focused, which may directly cause the hole block...

AI Technical Summary

Problems solved by technology

However, the traditional angle-selective filter uses Bragg diffraction efficiency, and the filtered beam is diffracted light, and the optical axis of the filter input light and output light has obvious deflection, which makes the traditional angle-selective filter unable to operate at high The use of plug-and-play in the power laser system brings difficulties to the optical path design and adjustment of the laser system. In addition, although the traditional low-pass filter can control the small-scale self-focusing effect to a certain extent, but too much mid-high frequency The "bleeding" of components will cause the fill factor of the top-hat beam to drop, thereby reducing the energy extraction efficiency of the gain medium when the beam passes through the laser amplifier

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