从混合介质的折射率、黏度、密度和声速等物理量随混合比的变化关系入手,推导出了混合介质的布里渊线宽、声子寿命和增益系数等受激布里渊散射(SBS)参数随混合比的变化关系.数值模拟了HT-70/FC-72混合介质的布里渊线宽、声子寿命和增益系数随FC-72体积分数的变化关系,并测定了该混合介质的吸收系数和光学击穿阈值随FC-72体积分数的变化关系.结果表明,HT-70/FC-72混合介质的SBS参数随FC-72体积分数单调变化,不出现极值现象.混合介质的选用不仅增加了SBS介质的种类,而且能够满足SBS系统对不同介质的需求.
From the relation between the refractive index, viscosity, density, sound velocity and mixing ratio of mixed medium, we deduce the variation of SBS parameters, namely the Brillouin linewidth, phonon lifetime and gain coefficient, with mixing ratio. For the HT-70/FC-72 mixture, the variations of Brillouin linewidth, phonon lifetime and gain coefficient with mixing ratio are numerically simulated, and the variations of absorption coefficient and optic breakdown threshold with mixing ratio are measured in experiment. The results show that the SBS parameters exhibit a monotonic variation with mixing ratio without extrema. The use of mixed medium not only diversifies SBS medium but also optimizes the SBS system.