The third-order nonlinear optical susceptibility of AlxGa1-xAs/GaAs asymmetric triple quantum wells

The multiple quantum wells (QWs) structure provides a unique opportunity to investigate the effect of structural parameters on nonlinear optical properties. The electronic and optical properties of GaAs/AlGaAs asymmetric triple QWs are analyzed by taking into consideration of geometrical confinement effect. The three QWs have different confined potentials by modulated, so the well width L, the barrier width b, and the aluminum doping concentration x are the adjustable structural parameters discussed crucially in this paper. The electronic energy levels and the associated wave functions are obtained by means of the finite difference method. The obtained results show that the third harmonic generation (THG) is directly related to these structural parameters. The THG susceptibility magnitude and the resonance energy could be adjusted, and a blue-shift or a red-shift can be obtained as the structural parameters are appropriately selected. Furthermore, the optimal structural parameters of asymmetrical triple QWs are discussed to obtain the strongest THG intensity. The results above give us a new strategy for designing optoelectronic devices based on the THG susceptibility.