Simulation analysis of spatial transmission of backward stimulated Brillouin scattered light in high power laser facilities

Abstract

Backward light by stimulated Brillouin scattering (SBS) induces the final transport mirror laser damage, which has been considered a bottleneck problem in developing high-power and high-energy laser facilities. In this work, an improved continuous phase plate (CPP) model and a backward SBS model were established based on the G-S algorithm and the Fresnel diffraction transmission algorithm to simulate the backward SBS to the final transport mirror. This study discussed the propagation characteristics of backward SBS. The research results showed that the distribution of the backward SBS transmitted to the final transport mirror was determined by the phase structure of the continuous phase plate attached to the back-transmission process. By optimizing the CPP design, reducing the transmission distance, reducing the intensity modulation, and controlling the phase of the incident beam, the modulation of backward SBS can be suppressed, which has great significance in improving the laser-induced damage threshold to the final transport mirror.