强外场调控下半导体中浅杂质态的光学吸收特性

理论研究了法拉第位形下强太赫兹激光场、磁场以及压强作用下半导体中浅杂质态非线性光学性质.利用含时非微扰理论——强太赫兹激光场效应被精确包含在激光缀饰库仑势中——和变分法计算出浅杂质态电子能级和波函数，然后基于紧致密度矩阵方法研究强外场和压强对浅杂质态1s→2p_z跃迁的线性、三阶非线性及总的光学吸收系数和折射率变化的影响.研究发现压强和强外场通过激光缀饰库仑势可调控跃迁能和几何因子的增大或减小，所以饱和吸收不但依赖于入射光强和弛豫时间而且还依赖于强外场，在强激光场强度和回旋共振区域附近饱和吸收更容易实现.线性、三阶非线性及总的光学吸收系数和折射率变化的共振峰位置和振幅，在选取合适的外场参数下不但受到强外场的有效调控，而且还受到压强的强烈影响.研究结果为设计强外场调控的新型高效基于杂质电子器件提供了理论支持.

Optical properties of shallow-impurity states in bulk semiconductors tuned by intense external fields

A theoretical study has been presented on the nonlinear optical properties of shallow-impurity states in semiconductors subjected to hydrostatic pressure, magnetic and intense terahertz laser fields within the Faraday configuration. The shallow-impurity energy levels and their wave functions are obtained using a combination of nonperturbative and variational methods in which intense laser field is exactly included via a laser-dressed Coulomb potential(LdCP). The combined effects of two external fields and hydrostatic pressure on the linear, third-order nonlinear, and total optical absorption coefficients (OACs) and reflective index changes (RICs) for the transition are investigated using a compact density-matrix approach. It is find that the transition energy and geometric factors can be increased or decreased by changing two external fields through the LdCP or by changing hydrostatic pressure. As a result, saturable absorption depends not only on the incident optical intensity and relaxation time but also on two external fields, which is more easily realized in high laser filed intensity or in the vicinity of cyclotron resonance region. The peak positions and magnitudes of the linear, third-order nonlinear, and total OACs and RICs can be effectively adjusted with an appropriate choice of two external fields, which are also intensively affected by the hydrostatic pressure. These theoretical findings hold promising applications in designing new efficient impurity-based devices manipulated by two external fields.