Characteristics of spectral beam combining with sinc-apodized Bragg grating

Spectral beam combining technology is an effective approach to obtain high-power laser output. The side-lobe in diffraction efficiency of reflection Bragg grating is the main factor which limits the efficiency of spectral beam combining. In this paper, the theoretical model of spectral beam combining system based on the sinc-apodized Bragg grating is proposed. The diffraction characteristic of the sinc-apodized grating is analyzed by the chain-matrix approach, and the effects of spectral width and beam divergence on combining efficiency are considered. Numerical analysis show that the side-lobe in diffraction efficiency is suppressed well after using the sinc-apodized grating, the peaks of the first side-lobe and second side-lobe are reduced from 62% and 36% to 0.57% and 0.12%, respectivel