Effect of structural and field parameters on optical refractive index changes in an asymmetric GaAs/AlGaAs three-step quantum well

The effective mass envelope function and diagonalization methods are used to obtain the sub-band energy eigenvalues and eigenfunctions of the structure. Then, the nonlinear refractive index changes of the structure are approximated by the compact density matrix. Hereafter, the structural parameters of the quantum well and the external electromagnetic field are adjusted to maximize the refractive index change response, whereas the dipole matrix elements are regulated according to the degree of energy separation between the wave functions, aiming to improve the optical performance and clarify the value of parameter adjustment. Our findings can be of interest in parameter design and experimental applications of optoelectronic devices for the selection of the more appropriate nonlinear optical configuration.