Angle dependence of chromatic polarization converstion of terahertz radiation by a density-modulated two-dimensional electron system

Abstract

Results of a theoretical investigation of the angle dependence of chromatic polarization conversion of the electromagnetic wave (EW) in a density-modulated two-dimensional (2D) electron system are presented. A giant enhancement of the polarization conversion efficiency is found to emerge under plasma oscillation resonance in the periodic 2D electron system. At normal incidence, the greatest polarization conversion takes place when the angle between the plane of incidence of the EW and the direction of the periodicity of the system (azimuthal angle)is equal to 45°. At oblique incidence, the value of the azimuthal angle, at shich the maximum polarization conversion in the system occurs, deviates from 45° depending on a particular value of the contrast ratio of dielectric constants of media surrounding the 2D electron system. The greater the contrast ratio, the smaller the deviation. In the total reflection regime, the total polarization conversion can be reached, if the electron scattering in the 2D electron system vanishes. In contrast to the refringence case, the frequency of the polarization conversion resonance deviates with the angle of incidence and azimuthal angle at the total reflection regime as a result of the field confinement in the vicinity of the 2D electron system. Numerical calculations are performed for the characteristic parameters of an actual 2D electron system in the electron inversion layer on p-Si at the terahertz frequencies.