Exciton effects on dipole-allowed optical absorptions in a two-dimensional parabolic quantum dot

Exciton effects on the linear and nonlinear optical absorptions (the transition from the S state (L=0) to the P state (L=1)) in two-dimensional quantum dots are theoretically studied by using the configuration-integration methods (CI) and the compact density-matrix approach. The results show that the optical absorption coefficient, which can be controlled by the confinement potential strength and the incident optical intensity, is enhanced obviously when the exciton effect is taken into account. We find that both a trapped electron-hole pair and the incident optical intensity can bleach the exciton absorption and the appearance of the new absorption may be due to biexciton.