光学击穿对受激布里渊散射特性的影响

把雪崩电离模型引入受激布里渊散射模型中，数值模拟了无光学击穿和有光学击穿时受激布里渊散射能量反射率随输入光功率密度的变化规律.实验上选取净化和未净化的CCl₄作为散射介质，在Nd:YAG调Q激光系统中进行了验证，理论与实验符合得很好.结果表明：当无光学击穿时，随着输入光功率密度的增大，能量反射率先是非线性增大，然后缓慢增大趋于饱和；而当有光学击穿时，随着输入光功率密度的增大，能量反射率先是非线性增大，达到最高值之后开始下降，最终趋于零.无光学击穿时的能量反射率及其稳定度明显高于有光学击穿时的情况. 关键词： 受激布里渊散射 光学击穿 雪崩电离

Influences of optical breakdown on stimulated Brillouin scattering

Avalanche ionization model is introduced to the coupled stimulated Brillouin scattering (SBS) equations. Numerical simulation of SBS energy reflectivity as a function of pump intensity is made with and without the optical breakdown factor in the equations. In the experiment, purified and unpurified CCl_4 media are studied with an Nd:YAG laser system with Q switch, the results are found to agree well with the numerical solutions. It is observed that under conditions that the optical breakdown does not occur, the energy reflectivity increases nonlinearly with pump intensity until reaching a certain value above which it tends to grow slowly. In cases with the breakdown, the energy reflectivity first increases nonlinearly with the pump intensity to a peak value and then decreases dramatically as optical breakdown occurs. The stability of energy reflectivity in the cases without optical breakdown is obviously better than cases otherwise.