Effects of magnetic, electric, and intense laser fields on the optical properties of AlGaAs/GaAs quantum wells for terahertz photodetectors

Abstract

We investigate optical absorption coefficients and changes in the refractive index in single- and double-step GaAs/AlGaAs quantum wells under the influence of magnetic, electric, and intense laser fields. For single-step quantum wells, increasing the intensity of the external laser and electric fields induces a red-shift in the total optical absorption coefficient and change in the refractive index and increases their amplitudes; however, increasing the magnetic field generates a blueshift in the optical absorption and change in the refractive index. For double-step quantum wells, the transition energy between the ground and first excited state is strongly decreased. In addition, the total optical absorption coefficients and changes in the refractive index incur a blue shift when the electric and magnetic fields are increased and a red-shift with increasing laser fields. Our analysis of coupling matrix elements, probability densities, and energy levels show that intense laser, electric, and magnetic fields can be harnessed to adjust and tune total optical absorption coefficients and refractive indices for terahertz applications.