提出以单缺陷双边带非线性载流子输运方程描述InP∶Fe中光折变动态光栅的写入过程,通过微扰法将非线性方程线性化,从而求得小调制干涉图样下空间电荷场的稳态解,并用耦合波方程建立空间电荷场与增益系数的关系。研究温度、泵浦光强、外加直流电场和入射角对增益系数的影响。结果表明,增益系数存在温度-光强共振,最佳泵浦光强强烈依赖于晶体工作温度;施加直流电场对增益系数有明显提升作用,在10 kV·cm ^-1范围内增益随外加直流电场增加而线性增加;并且,在温度-光强共振条件下存在最佳入射角。在室温为298 K和外加电场为5 kV·cm ^-1时,最佳泵浦光强为218 mW·cm ^-2,最佳入射角为5°。通过InP∶Fe双波混频实验研究泵浦光强、外加直流电场和入射角对增益系数的影响,实验结果表明,增益系数变化规律与理论预测一致,验证了单缺陷双边带模型的合理性,该研究为Ⅲ-Ⅴ族半导体光折变晶体的双波混频研究提供重要的参考价值。

The writing process of photorefractive dynamic gratings in InP∶Fe was described with nonlinear carrier transport equations based on a one center-two band model, which were then linearized by perturbation. As a result, the steady-state space charge field in a small-modulation interference pattern was solved, and the relationship between the space charge field and the gain coefficient was established by coupled wave equations. Furthermore, the effects of temperature, pump intensity, external direct current (DC) electric field, and incident angle on the gain coefficient were examined. It turns out that the gain coefficient exhibits temperature-intensity resonance and the optimal pump intensity is strongly dependent on the operating temperature of crystals. The gain coefficient can be significantly improved by an external DC electric field and the gain increases linearly with the enhancement of the electric field below 10 kV·cm ^-1. There is an optimal incident angle in the case of temperature-intensity resonance. The optimal pump intensity is 218 mW·cm ^-2 and the optimal incident angle is 5° at the temperature of 298 K and the external electric field of 5 kV·cm ^-1. Also, we experimentally investigated the relationships of the pump intensity, external DC electric field, incident angle with the gain coefficient through two-wave mixing in InP∶Fe. The results show that the change rule of the gain coefficient agrees with the theoretical predictions, verifying the rationality of the one center-two band model. This work has an important reference value for the research on the two-wave mixing of III-V semiconductor photorefractive crystals.