In this paper, the numerical computation for the absorption coefficient and the relative refractive index change, considering the third order correction nonlinear optical properties, is reported. This study was performed for a symmetric two-step GaAs/Ga1-xAlxAs quantum well, subjected to a constant electric field applied along the growth direction z, and an in-plane constant magnetic field B. We also consider the intense laser field effect, characterized through the laser-dressing parameter alpha(0). The electronic structure computation was obtained by working under the effective mass approximation and the Schodinger equation was solved by diagonalization procedure. The optical properties are calculated by using the well-established compact density matrix formalism expressions for the nonlinear optical properties of interest. In general, we found that the structural parameters, as the step-like potential or the central barrier, permit the resonant peak and the amplitude design. We also found that the system becomes more sensitive to electric than to magnetic field, and finally that the intense, non-resonant, laser field can strongly change the optical properties of interest. Our results indicate that the implementation of the step-like potential profile, experimentally feasible, enhance the optical properties of interest, that falls within the THz electromagnetic range, and can be used to design a photodetector, or even can be used for quantum cascade lasers design.