Theoretical and Experimental Research on Laser-Induced Damage of Fused Silica Optics Due to Stimulated Brillouin Scattering

The damage behavior of fused silica optics induced by stimulated Brillouin scattering (SBS) was studied theoretically and experimentally based on a coupled-wave theory. The SBS-induced damage mechanism was systematically investigated by analyzing the evolutions of the Stokes-light intensity and induced stress as a function of laser pulse shape, thickness, and surface reflectance of the optics. The results show that the SBS-induced damage often occurs on the front surface of the fused silica optics. The Tophat beam has the most effect on an SBS-induced damage, followed by a focused Gaussian pulse. SBS effect is strongly thickness dependent, which is associated with the gain length. The SBS-induced damage can be efficiently suppressed by decreasing the surface reflection of the optics. Good agreements are obtained between the experimental and theoretical results, which strengthen our understanding of the damage mechanism of fused silica and provide a favorable reference for developing high-power laser systems.