Optical Rectification and Second Harmonic Generation on Quasi-Realistic InAs/GaAs Quantum Dots: With Attention to Wetting Layer Effect

Abstract

In this paper, we have performed a theoretical study on nonlinear optical rectification (OR) and second harmonic generation (SHG) for three-level dome-shaped InAs/GaAs quantum dots (QDs) in the presence of wetting layer (WL). We used the compact density matrix framework and effective mass approximation to investigate the second order nonlinear phenomena on InAs/GaAs QD. It is demonstrated that second harmonic generation (SHG), optical rectification (OR), and their mutual absorption and refractive index changes are quite sensitive to the size of QDs. The size variations have profound irregular behavior owing to distribution of envelope function on WL and QD simultaneously. Moreover it is found that R=13 nm is a critical radius where the regular variation takes place. It is shown that size variation causes blue shift until Critical radius (R=13 nm) and after that, increasing the QD size lead to redshift in second order phenomena.