半抛物量子阱中二阶非线性光学性质的研究

The study of two-order nonlinear optical properties in semiparabolic quantum well

本文对外加电场作用下GaAs/AlGaAs半抛物量子阱非线性光整流和二次谐波极化率进行了研究.首先,本文运用密度矩阵和迭代的方法获得外加电场作用半抛物量子阱系统光整流和二次谐波极化率的表达式.同时,采用有限差分法求得多外加电场作用下该系统的能级和波函数,避免了精确求解过程中的多重不恰当近似.结果表明:1)有限差分法计算结果相当精确;2)外加电场和受限势频率与系统能级、受限势形状、以及光整流和二次谐波极化率有着密切的关系,同时,可以通过外加电场和受限势频率实现对该系统光整流和二次谐波极化率的有效调控.将为基于子带跃迁的光电子器件的制备提供理论基础.

Studies aimed at understanding the nonlinear optical properties of GaAs/A1GaAs semiparabolic quantum well under applied electric have focused on optical rectification and second harmonic generation. These studies have taken two complimentary approaches： （1） the compact-density-matrix approach and iterative method have been used to obtain the expressions of optical rectification and second harmonic generation; （2） the finite difference techniques have been used to obtain the energy eigenvalues and their corresponding oeigenfunctions of the semiparabolic quantum well under applied electric field. The energy eigenvalues, the shape of the confined potential, optical rectification and second harmonic generation are modulated by the confined potential frequencies and electric field. So the results of a number of numerical experiments indicate that the nonlinear optical rectification and second harmonic generation strongly depends on the confined potential frequencies and applied electric field. This gives a new degree of freedom in various device applications based on the intersubband transitions of electrons.