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

A Khaledi-Nasab,V Fallahi,M Sahrai,M Sabaiean

doi:10.1155/2013/530259

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.

Highlights

In the last few years the nonlinear optical properties of intersubband transitions in semiconducting materials have attracted remarkable attention due to the potential application in electronics and optoelectronics devices [1,2,3,4,5,6,7,8,9,10,11,12,13]
The Polaron effect in optical rectification (OR) and second harmonic generation (SHG) in cylindrical quantum dots (QDs) was studied by Liu et al [36]; they made a focus on the dependence of both the OR and the SHG on confinement frequency, external magnetic field, and the linear potential coefficient V
The effect of size under different values of electric and magnetic fields on SHG for parabolic studied by Li et al [42]; the length-dependent SHG on cubical QDs as function of incident photon energy was presented by Shao et al [43]

Summary

Introduction

In the last few years the nonlinear optical properties of intersubband transitions in semiconducting materials have attracted remarkable attention due to the potential application in electronics and optoelectronics devices [1,2,3,4,5,6,7,8,9,10,11,12,13]. The Polaron effect in OR and SHG in cylindrical QDs was studied by Liu et al [36]; they made a focus on the dependence of both the OR and the SHG on confinement frequency, external magnetic field, and the linear potential coefficient V. The effect of size under different values of electric and magnetic fields on SHG for parabolic studied by Li et al [42]; the length-dependent SHG on cubical QDs as function of incident photon energy was presented by Shao et al [43]. Sabeian and Khaledi-Nasab highlighted the size-dependent intersubband optical properties of dome-shaped InAs/GaAs quantum dots with wetting layer [44]. In this work we are presenting a deep understanding of the OR and SHG in a three-level dome-shaped InAs/GaAs QDs with WL using finite element method (FEM) and compact density matrix framework. By taking all resonant and nonresonant terms of second order nonlinear susceptibility under consideration, the effect of all expressions is being highlighted

Theoretical Framework

Result and Discussion

Conclusion