Morse势阱中线性和三阶非线性光折射率的改变  

Linear and Third-order Nonlinear Change in the Index of Refraction in Morse Quantum Well

作　　者：于凤梅[1] 郭康贤[2] 王克强[1] 

机构地区：[1]仲恺农业技术学院计算机与电子工程学院,广东广州510225 [2]广州大学桂花岗校区物理系,广东广州510405

出　　处：《发光学报》2005年第5期569-574,共6页Chinese Journal of Luminescence

基　　金：国家自然科学基金(60478010);广东省自然科学基金(04105406;2004B10301014)资助项目

摘　　要：利用量子力学中的密度矩阵算符理论和迭代方法,导出莫尔斯(Morse)势阱中线性和三阶非线性光折射率改变的解析表达式,并以典型的GaAs/A lGaAsMorse势阱为例进行数值计算。数值结果表明,随着入射光强度增强,总的折射率改变将减少;随着势阱参数a的增大,总的折射率改变将减小;而随着载流子浓度的增加,总的折射率改变将增加。结果表明要获得较大的折射率改变,则需选取较小的入射光强度,较小的参数a,较大的载流子浓度,从而为实验研究提供理论依据。A large number of researches have shown that the low dimensional semiconductor materials are the ideal nonlinear optical materials. With the progress of crystal growth technology, many low dimensional quantum systems with different dimensions and sizes can be fabricated. So the nonlinear optical effects in the low dimensional semiconductor materials become the important research aspects. Analytic formulas for the linear and third-order nonlinear changes in the index of the refraction are obtained for Morse quantum wells by the compact density matrix method and the iterative procedure. The numerical results are presented for a typical GaAs/A1 GaAs Morse quantum wells. The numerical results reveal that, the linear refractive index changes are not related to the incident optical intensity. However, the incident optical intensity has a striking influence on the third-order nonlinear refractive index changes. When the incident optical intensity increased, the total refractive index change will reduce. When the parameter increased, the total refractive index changes will decrease. When the carrier density increases, the total refractive index changes will increase. By contrast, it can be seen that the total refractive index changes equals to zero at the peak value of the optical absorption. So the large changes in the index of refraction can be obtained when the optical absorption is small.

关 键 词：非线性光学 光折射率改变 MORSE势阱 密度矩阵方法 

分 类 号：O472.3[理学—半导体物理]