非相干辐照对LiNbO_3:Fe晶体光折变非线性的影响与控制作用

The influence and control of incoherent irradiation on photorefractive nonlinearity of LiNbO_3:Fe crystal

研究了非相干辐照对LiNbO3:Fe晶体中从自散焦到自聚焦的动态转换过程的影响和控制作用 .无论是从前向还是从背向加入非相干辐照 ,都能加快自散焦、自聚焦过程以及从自散焦到自聚焦的转换过程 ,增大折射率的变化值 .当非相干辐照以一定的时间间隔重复辐照在晶体上时 ,透射功率能迅速地上升和下降 ,具有明显的开关效应 .这种在非相干辐照控制下折射率的迅速改变有望应用于全光学开关器件 .

In this paper, we study the influence of incoherent irradiation on the conversion process front self-defocusing to self-focusing in LiNbO3 : Fe crystal under the open-circuit condition. We observe that the incoherent irradiation can increase the refractive index change, fasten greatly the process of self-defocuisng, self-focusing and the conversion from the former to the latter in Li-NbO3 : Fe crystal, whether it propagates along the direction of the incident light or the opposite direction. When the incoherent light illuminates the crystal in certain time intervals repeatedly, the transmissivity can rise up and fall down quickly, the obvious switching effect is observed. The change of the refractive index controlled by the incoherent irradiation can be applied in the all-optical switch.