强非线性吸收下高斯光束Z-扫描衍射理论模型

 摘要：在同时考虑非线性折射和非线性吸收的情况下，借助光的衍射理论，研究了Z-扫描技术的衍射理论模型，分析了非线性折射和非线性吸收同时存在时Z-扫描曲线的形状特征和变化规律。数值计算表明，非线性吸收相移和非线性折射相移的比值是影响接收小孔输出光功率的重要因素。要想得到好的光限幅效果，应选取非线性相移比值远小于1或远大于2的非线性材料。

Gaussian beam Z-scan diffraction theory model for the strong nonlinear absorption materials

Taking the nonlinear refraction and the nonlinear absorption into account simultaneously, this paper investigated the diffraction theory model of the Z-scan technique, and analyzed the features of Z-scan curves and their variation rules. In the case of small nonlinear refraction and absorption the results obtained by this theory are consistent with that of the conventional Z-scan theory. For the materials with the large nonlinear refraction and absorption, the conventional theory become ineffective, but this theory can still give very good results. Numerical results show that the ratio of the nonlinear refraction to absorption is an important parameter that influences the optical power transmitted from the receiving aperture. To acquire a good optical limiting performance, the ratio of the nonlinear refraction to the absorption of the optical limiting materials must be either much smaller than 1 or much larger than 2.