Design and polarization characterization of diffraction grating for spectral beam combining

Semiconductor external cavity spectral beam combining technology is of great significance for obtaining direct semiconductor laser sources with high power, high brightness, and high beam quality, and has received extensive attention from domestic and foreign research organizations. Diffraction grating is a key component in the external cavity spectral beam combining structure. In this paper, a rectangular diffraction grating with a center wavelength of 960 nm is designed, and the effects of the grating period, groove depth, and laser incidence angle on each reflection and diffraction order of the grating are analyzed and the grating is optimized to obtain rectangular diffraction grating with maximum diffraction efficiency of 92.77% for the -1 order. At the same time, the diffraction efficiency of -1 order is more than 90% at the incidence angle of 61° - 63.5°and more than 92% in the wavelength range of 945nm - 972nm, which can be used for high-power laser output to meet the requirements of external cavity spectral beam combining.