应用微扰展开法于“跳跃模型”,给出了空间电荷场前三阶分量随时间、外加电场等变化的解析表达式。同时讨论了外加电场对各阶空间电荷场建立的影响。当扩散场与外加电场可比拟时,外加电场对空间电荷场的影响不大;随着空间电荷场阶数的提高,其达到最大饱和值所需的外加电场越小。在外加电场作用下,空间电荷场各阶分量随时间呈振荡衰减,直到达到饱和。外加电场越大,振荡越强烈,周期越短。在考虑高阶分量的贡献后,空间电荷场的振荡幅度加大。

The analytic expressions for the first three higher order harmonics of the space charge field versus time and the applied field are presented by using perturbative expanding to “the hopping model” of Feinberg. The results are valid for arbitrary strengths of characteristics′ fields in the photorefractive materials with arbitrary values of the modulation depths. We aslo study the effect of the applied field on recording of the first three higher order harmonics of the space charge field. It shows that the effect on the space-charge field is very small at case of large diffusion field. The applied field for the maximum saturation values becomes small with the order increasing. With an applied field, higher-order harmonics of the space-charge field show oscillating attenuation versus time until to reach saturation state. The oscillating is strong as the applied field increases with shorter oscillating period. The oscillating amplitude of the space-charge field increases while the contribution of the higher-order harmonics are considered.