从理论上研究了材料的非线性折射和非线性吸收同时存在时,闭孔Z-扫描透过率曲线的特征,结果表明峰-谷或谷-峰结构特征取决于材料的三阶非线性极化率的虚部与实部的比值ρ.给出了高斯光束情况下决定峰-谷或谷-峰结构存在与否的精确临界值ρc和曲线的某些特征参量与ρ的关系以及本理论的适用范围.CS2的Z-扫描实验与理论结果符合得很好.

Some features of the closed aperture Z-scan transmittance curves of nonlinear optical materials with Gaussian beam have been studied theoretically when the nonlinear refraction and the nonlinear absorption coexist. It is found that the peak valley or valley peak structure depends on the ratio ρ of the real part to the imaginary part of the third order nonlinear susceptibility. The exact critical value ρc, which determines whether the peak valley or valley peak structure exists or not, is given; the ρ dependences of some parameters of the transmittance curves are obtained numerically, and the scope of applications for the results is also discussed. The Z-scan experiment of CS 2 is consistent with the theoretical results obtained here.