为研究高能激光在水中产生受激布里渊散射(SBS)的机理,提出了一种基于强激光非线性极化和非线性吸收的非均匀折射率光栅结构模型,分析了水中SBS产生的物理机制及光谱特性。通过建立非均匀折射率光栅的调制结构以及周期结构,研究了水中SBS非均匀折射率光栅的产生机理;利用传输矩阵法分析了非均匀折射率光栅结构对SBS线宽、频移、衍射效率等光谱特征的影响,并与实验测量结果进行了比对。结果表明:理论模拟与实验测量结果吻合良好,利用非均匀折射率光栅结构模型可以有效地分析水中SBS产生的物理机理。

To study the mechanism of stimulated Brillouin scattering (SBS) excited by high energy laser in water, a structure model of a non-uniform refractive index grating based on nonlinear polarization and nonlinear absorption of high intensity laser is proposed, and the physical mechanism and spectral characteristics of SBS in water are analyzed. The mechanism of the non-uniform refractive index grating generated by SBS effect in water is studied by establishing the modulation structure and periodic structure of the non-uniform refractive index grating. The effect of the structure of the non-uniform refractive index grating on the spectral characteristics of SBS, such as linewidth, frequency shift, and diffraction efficiency, is analyzed by using the transfer matrix method. Also, the theoretical simulation results are compared with the experimental results. The results indicate that the theoretical simulation results are in good agreement with the experimental results, and the physical mechanism of SBS in water can be analyzed effectively by using the structure model of the non-uniform refractive index grating.