Parity-time symmetry and asymmetric diffraction of light in four-level triple quantum wells

Abstract

In this paper, we investigate two-dimensional parity-time (PT) symmetry and electromagnetically induced grating (EIG) in four-level asymmetric triple quantum wells (QWs). Here, PT-symmetry and EIG are realized by appropriately varying the detuning value of the probe, and the modulation amplitudes of a coupling field and standing wave (SW) pump. By virtue of its PT symmetry, the EIG asymmetrically diffracts the probe beam. The angular switching of the diffracted beam can be achieved either by varying the probe or the coupling and SW pump fields. The intensity distribution of the diffracted beam over higher-order diffraction peaks depends on the interaction length in the QW. For small interaction lengths, most of the energy is distributed close to the central diffraction peak. With an increase in the interaction length, energy is gradually transferred to higher order diffraction peaks.