Binding energy and the third-order nonlinear optical susceptibility of an exciton in GaAs/AlGaAs core/shell spherical quantum dot

摘要

In this study, we have calculated the energy levels and binding energies for exciton associated with the ground state and some low-lying states in GaAs/AlGaAs core/shell spherical quantum dot (QD) by using the finite difference method. The correctness of the numerical results is verified by comparison with the analytical solution without considering exciton effects. Simultaneously, the third harmonic generation (THG) in GaAs/AlGaAs core/shell spherical QD is theoretically investigated within the framework of the compact-density-matrix approach and iterative method for both cases with and without exciton effects. All paths of the system are considered which generates third harmonics. Our results indicate that the energy levels and binding energies are depended dramatically on the size of the QD. The THG is greatly enhanced because of the quantum confinement of exciton. It is over two times bigger than that obtained by without considering exciton effects. In addition, the resonant peaks and its corresponding to resonant energy are also taken into account.