偶氮乙基橙掺杂聚乙烯醇薄膜自衍射效率的动态特性分析

两束强度相等的相干光小角度在乙基橙－聚乙烯醇(EO/PVA)膜中耦合时，产生自衍射现象．我们对自衍射效率的动态特性进行了实验研究,实验表明：(1)当入射光强较小（I＝100mW/cm2）时，一阶衍射效率η随照射时间的延长从零上升至一稳定值；(2)入射光强较大（I＝480mW/cm2）时，一阶衍射效率η 从零开始迅速上升到一最大值η_m后再降至一稳定值η_s. 以耦合光在膜中的干涉光场对trans-cis态的分子数分布进行调制而形成的粒子数光栅为模型，对衍射效率的动态特性进行了理论分析,理论与实验结果相符合。

Characteristics of self-diffraction efficiency of ethyl orange polymer film

When two coherent beams illuminate into the ethyl orange doped polymer film with small angle and equal intensity, the phenomena of self diffraction occur. We explored the dynamic characteristic of self-diffraction efficiency experimentally. The experiment results are the following: 1) The diffraction efficiency η increases monotonously from zero to a stable value ηs with the illumination time illuminated by lower intensity（I＝100mW/cm2）. 2) The diffraction efficiency η increases to a maximum ηm at first and then decreases to a stable value ηs illuminated by higher intensity. We analyzed the phenomenon theoretically by the model of population grating, which is formed by the molecules populations of trans and cis modulated by the coherence optical field. The theoretical results are consistent with the experimental results.