聚吡咯甲烯/聚乙烯醇薄膜对高斯光束的衍射行为

Diffraction Behavior of Polypyrrylarylenemethine/Polyvinyl Film to Gaussian Beam

制备了一种新型有机聚合物 (聚吡咯甲烯 )与聚乙烯醇的非线性光学复合薄膜 ,在该样品的激光纵向扫描实验中发现 ,随着样品相对于高斯光束束腰位置的不同 ,产生了两种不同结构的同心衍射环。理论分析表明 ,该现象可以用光克尔效应和热光非线性效应共同作用下的附加相位孔对入射光束的衍射行为来解释。从菲涅耳基尔霍夫衍射积分公式出发 ,建立了非线性光学介质对高斯光束的衍射模型 ,通过数值积分 。

A new type of organic polymer nonlinear optical compound film known as polypyrrylarylenemethine/polyvinyl film was prepared. In the Z-scan experiment, two types of concentric diffraction rings were observed in the far field depending on the position of the sample relative to the Gaussian beam waist. This phenomenon can be explained by the diffraction effect of the Gaussian beam from the laser-induced phase-hole in the nonlinear medium caused by Kerr effect and thermo-optic effect. Based on Fresnel-Kirchhoff diffraction integral equation, a mathematical model on the diffraction of nonlinear optical media to Gaussian beam was established. The numerical calculating results are in good agreement with the experimental data.