研究了正切平方势阱中的子带光吸收,用量子力学中的密度矩阵算符理论和迭代法推导出了 正切平方势阱中线性和三阶非线性光学吸收系数的解析表达式,并以典型的GaAs/AlGaAs正切平方量子 阱为例进行数值计算。计算结果表明,该势阱中的势阱宽度b、 势阱深度V0和入射光强I对吸收系数有很大影响。随着势阱宽度b的增加和势阱深度V0 的减小,总吸收系数的峰值减小并且向低能方向移动。随着入射光强I 的增加,总吸收系数会减小,出现了光饱和吸收现象,同时吸收谱线的线宽随着入射光强的增大而增大。

Analytic expression for the linear and third-order nonlinear optical absorption coefficients was obtained in square tangent quantum well by the compact density-matrix method and the iterative procedure. The numerical results for typical GaAs/AlGaAs material show that the well width b, well depth V0 and incident intensity I have great influence on the absorption coefficients and the total optical absorption coefficients are induced with the enhancement of b and the reduction of V0. It is obtained that the peak absorption shift to the aspect of the low energy. Moreover, the peak of the total optical absorption coefficients is significantly induced and the strong absorption saturation will occur with increasing of the incident intensity.