Theoretical Research On A Number Of Nonlinear Optical Properties Of Semiconductor Microstructures

In this dissertation, the nonlinear optical properties in semiconductor microstructures are studied extensively. The nonlinear susceptibilities in specific microstructures are investigated based on the microscopic theory. Some processes of light propagating in a quantum dot are also discussed. The effective mass approximation is employed to describe electronic properties of the system.In the first part of this study, the nonlinear optical susceptibilities, which includes three topics, are studied. Firstly, the analytic expression for the third-harmonic generation (THG) in cylindrical quantum dots is derived by using the density matrix method. The numerical calculations are performed on a cylindrical GaAs/Al_βGa_1-βAs quantum dot with different incident photon energy, polarizations, and under various dot dimensions and Al concentrations. It is found that the THG is more than two orders of magnitude larger than that of bulk GaAs under appropriate conditions. Secondly, theoretical investigation of polaron effects on the THG due to intersubband transition in a quantum disk is presented. Contributions from the confined bulk longitudinal optical and the surface optical phonon modes are considered separately. Results show that the LO phonons and the SO phonons play different roles in influencing the THG. The polaron effects are quite significant, especially around the peaks, showing the necessity of taking the polaron effects into consideration. The third section of this part studies the optical rectification in a GaAs/Al_βGa_1-βAs quantum well, in which the effective mass is a function of the position in the well. It is found that the asymmetry of the quantum well causes a large optical rectification. The optical rectification is in reciprocal...