用多载流子模型分析了D型石英光纤的热极化过程及耗尽层的形成,分析了氢离子注入及钠离子耗尽层的形成。并把正负电荷的交界处类比为pn结,分别计算了所形成的内建电场大小。最终得出极化完成后石英光纤的二阶非线性效应主要由钠离子的耗尽形成,计算出的内建电场大小约为10~8 V/m,由此算出的二阶非线性系数的数值在0.10~0.60pm/V,和实验报道数值符合较好。 The multi-carrier model was used to analyze the thermal polarization and the depletion layer formation of D-type silica fiber. The hydrogen ion implantation and the formation of sodium ion depletion layer were analyzed. And the junction of positive and negative charges analogy pn junction, respectively, calculated the size of the built-in electric field. It is concluded that the second-order nonlinear effect of the silica fiber is mainly caused by the depletion of sodium ions after the polarization is completed. The calculated built-in electric field is about 10-8 V / m, and the second-order nonlinear coefficient Values ​​in the 0.10 ~ 0.60pm / V, and experimental values ​​in line with good.