Wave scattering on a domain wall in a chain of PT-symmetric couplers

TL;DR

This paper investigates wave scattering in PT-symmetric waveguide arrays with a domain wall, revealing amplification effects and frequency conversion phenomena during wave interactions.

Contribution

It introduces a domain wall in PT-symmetric couplers and analyzes the resulting wave scattering, highlighting novel amplification and frequency conversion effects.

Findings

Amplification of reflected and transmitted waves.

Excitation of different frequency components.

Wave scattering behavior influenced by the domain wall.

Abstract

We study wave propagation in linear arrays composed of pairs of conjugate waveguides with balanced gain and loss, i.e. arrays of the PT-symmetric couplers, where the linear spectrum is known to feature high-frequency and low-frequency branches. We introduce a domain wall by switching the gain and loss in a half of the array, and analyze the scattering of linear waves on this defect. The analysis reveals two major effects: amplification of both reflected and transmitted waves, and excitation of the reflected and transmitted low-frequency and high-frequency waves by the incident high-frequency and low-frequency waves, respectively.