Influence of dark irradiation on transition process from self-defocusing to self-focusing in LiNbO3:Fe crystals
在LiNbO3:Fe晶体中暗辐照对光束从自散焦向自聚焦转换过程的影响

We have studied the dynamic propagation of an optical beam from self-defocusing to self-focusing in photovoltaic photorefractive crystals LiNbO 3:Fe in the framework of a two-dimensional band transport model. The results show that dark irradiation plays an important part in the transition process. The transition occurs only when the normalized dark irradiation is very small. We discuss also the influence of pyroelectric effect on the transition process.