Pöschl-Teller势阱中线性与非线性光学吸收系数的计算

非对称性量子阱中的非线性光学效应因其潜在的实用价值而引起了人们的广泛关注,而量子阱内带间的光学吸收问题对研究远红外光学探测器件具有重要的理论指导意义.考虑带间的电子弛豫,用量子力学中的密度矩阵算符理论导出了Pöschl-Teller 势阱中的线性与三阶非线性光学吸收系数的表达式.通过调节Pöschl-Teller势阱中两个可调参数κ和λ,势阱的形状及其非对称性会随着κ和λ的取值不同而明显不同,从而其线性与非线性光学吸收系数的大小也会随势阱参数κ、λ和入射光强的变化而呈规律性的变化,并且当入射光强增强到一定程度会出现较强的饱和吸收现象.

Calculation of Linear and Nonlinear Intersubband Optical Absorption in the Poschl-Teller Well

The problem of optical saturation of intersubband absorption has recently attracted considerable attention. The problem is very important to the development of superlattice devices such as fast infrared detectors and modulators because one needs to know the range of input optical intensities for which linear operation is possible. Analytical expression of the linear and the third-order nonlinear optical intersubband absorption coefficients are obtained in the Poschl-Teller well using the density matrix formalism taking into account the intrasubband relaxation. Since there are two adjustable parameters κ and λ in the Poschl-Teller well, the shape of the well will change with the change of the parameters κ and λ,accordingly the linear and the third-order nonlinear optical absorption coefficient will change with the parameters κ and λ.It is shown that the optical absorption coefficient depends on the parameter κ、λ,the tunnel bandwith and the optical intensity strong. The absorption saturation will occur with I increase. Numerical results are presented for a typical AlGaAs/GaAs Poschl-Teller well.