Peculiarities of light pulse propagation in quasi-PT symmetric periodic structures

Abstract

We study the peculiarities of light pulse propagation in the quasi-parity-time (quasi- P T ) symmetric periodic media in the Bragg geometry. Our focus is the investigation of the competition between the Bragg reflection and the P T symmetry contribution provided different pulse duration. The mechanisms of nonsymmetric interaction between the counterpropagating waves are revealed and the various regimes of the monochromatic and nonmonochromatic wave propagation are determined. It is demonstrated that regardless the gain and loss level, the propagation of so-called long pulses in a quasi- P T -symmetric medium is analogous to monochromatic waves propagation in a “pure” P T -symmetric medium. At the same time, the transmittance of the short pulses is accompanied by strong distortions determined by the gain and loss level.