为了分析大口径融石英光栅反射衍射导致的受激布里渊散射(SBS)损伤, 建立了光栅的设计分析模型, 计算了光栅从1到6级次的反射衍射角、焦距及效率; 根据SBS原理分析了未施加相位调制和施加相位调制下融石英光栅反射衍射的SBS增益及强度, 并结合工程实例验证了该分析结果的可靠性。实验结果表明：在未施加相位调制时, 融石英光栅反射衍射的SBS强度大, 元件损伤严重, 寿命短; 施加相位调制后, 光栅反射衍射的SBS增益大幅降低, SBS强度小于融石英的损伤阈值, 元件寿命得以显著延长。在实际的高功率激光系统中, 必须施加相位调制以抑制光栅反射衍射的SBS损伤。

In order to solve the stimulated Brillouin scattering (SBS) damage by reflected diffraction of fused silica grating with large aperture, we establish the design and analysis model of grating, the reflected diffraction angle, focal length and efficiency from 1 to 6 orders reflected diffraction of the grating are calculated. The gain and intensity of SBS with modulated laser and original laser are analyzed based on SBS principle, and the reliability of the analysis is verified by an engineering example. The experimental results show that the SBS intensity is large, the grating element is seriously damaged and its service life is short when the phase modulation is not applied. Moreover, when the phase modulation is applied, the SBS intensity is less than the damage threshold of fused silica and the service life of grating element increases evidently. In the actual high power laser system, phase modulation must be applied to suppress SBS damage of grating reflected diffraction.