Sensitivity of the Linear and Nonlinear Optical Properties to an Electric Field and Doping Density in CdSe/MgSe Single Quantum Wells

In the present work, we explored the impact of doping concentration and applied electric field on both linear and nonlinear optical properties based upon the intersubband transitions of CdSe/MgSe single quantum wells (QWs) in the framework of the effective mass approximation (EMA) using the compact density matrix approach. The energy levels and their relative wave functions were obtained by solving the coupled Schrödinger–Poisson equations by the finite difference method (FDM) under the envelope wave function approximation. The third-order nonlinear optical susceptibility, the refractive index changes (RIC), and the absorption coefficients (AC) were investigated as a function of doping concentration. The numerical results revealed that an increase in the doping concentration N_D results in a blue shift of the peak position of the linear and nonlinear optical properties, with a substantial enhancement of their magnitudes. The same behavior related to the third-order nonlinear susceptibility was noted when the considered structure was subjected to an external electric field.