Impurity-Related Linear and Nonlinear Optical Absorption Coefficients of Unstrained (In,Ga)N-GaN Symmetric Coupled QWs

Linear, third-order nonlinear and total optical absorption coefficients associated with intra-conduction band in wurtzite unstrained (In,Ga)N-GaN coupled quantum wells are calculated. Based on the effective-mass and the one-band parabolic approximations, the well and the barrier-widths effects are investigated variationally under finite confinement potential barrier. The results indicate that the structure size have a great influence on the optical properties. The results reveal also that larger optical absorption coefficients are obtained compared to single quantum well and a significant red-shift is obtained as the structure size increases. It is found that the modulation of the absorption coefficients can be easily obtained by adjusting the barrier and/or the well widths.