Impurity and eccentricity effects on the nonlinear optical rectification in a quantum ring under lateral electric fields

Abstract

Within the framework of the effective-mass approximation, the effect of different static perturbations—lateral electric field, impurity donor, and eccentricity distortion—on the nonlinear optical rectification in a GaAs disc-shaped quantum ring has been investigated. For a concentric ring, the influence of the lateral electric field and off-center impurities on the intraband transitions at two values of temperature was studied in detail. We found that the optical response strongly depends on the incident light polarization and donor position within the structure. Compared with the profile at 4 K, the optical rectification spectra exhibit at 77 K additional peaks of reduced magnitude in the low-frequency range. The main transition peaks become smaller, while their positions remain almost unchanged with temperature. For eccentric structures, relevant differences between small and large eccentricity regimes can be observed in the electronic properties. In this case, the energy spectra and the nonlinear optical response are very sensitive to the direction of the applied electric field. The effect can be used to identify the eccentricity of the system.