Research On The Impact Of SBS And Interface Structure Of Fused Silica On The Damage Process

The stimulated Brillouin scattering is one of the most important damage mechanism processes of optical materials. It is significant for the development of ICF physical experiments and high power solid-state laser facility to researching the effect of stimulated Brillouin scattering on the damage process of optical materials.In this thesis, transient stimulated Brillouin scattering(SBS) process and its impact on the damage process of optics were studied based on the nonlinear coupled-wave theory with FORTRAN programming language. The damage process and morphology were studied by simulating the distribution of stress induced by SBS process. In addition to studying the damage morphology of SBS process, we also discussed the role of the pump light parameters(wavelength, light intensity), the seed of light intensity and material parameters(length) in SBS process under rectangular pulse. By stimulating the development of SBS process development, the preliminary exploration of Gaussian pulse and focusing Gaussian pulses was carried out. The results show that the stress induced by SBS process can be up to 150 MPa, which is far beyond the tensile strength of fused silica and has a great impact on the damage process of optical materials.The effect of thickness and reflectivity on the damage process was investigated by testing the laser-induced damage threshold of samples with different parameters and specifications. The experimental results were consistent with the simulation results, which verified the correctness of the numerical result indirectly. As the thickness decreasing from 30 mm to 1 mm, the laser-induced damage threshold of fused silica increased from 16 J/cm2 to 25 J/cm2, which increased by 55 percent. The laser load capacity of antireflection coating samples have been improved compare with the original samples, which is more able to withstand laser irradiation. The energy density of 100% probability damage was up to 20 J/cm2 while the original samples’ was 17 J/cm2. The energy density of rear increased from 16.20 J/cm2 to 20.19 J/cm2, which increased by 25 percent.