Nonlinear parity-time-symmetric transition in finite-size optical couplers

TL;DR

This paper predicts a nonlinear transition in finite-size optical couplers that switch between symmetric and broken parity-time regimes, offering new avenues for ultracompact all-optical signal processing.

Contribution

It introduces the concept of a nonlinear $ ext{PT}$-symmetric transition in finite-size optical systems, including conventional discrete waveguide couplers.

Findings

Nonlinear $ ext{PT}$-transition occurs in finite-size systems.

Transition can be triggered by nonlinear effects.

Results suggest feasible experimental realization.

Abstract

Parity-time-symmetric ($\mathcal{PT}$-symmetric) optical waveguide couplers offer a great potential for future applications in integrated optics. Studies of nonlinear $\mathcal{PT}$-symmetric couplers present new possibilities for ultracompact configurable all-optical signal processing. Here, we predict nonlinearly triggered transition from a full to a broken $\mathcal{PT}$-symmetric regime in finite-size systems described by smooth permittivity profiles and, in particular, in a conventional discrete waveguide directional coupler configuration with a rectangular permittivity profile. These results suggest a practical route for experimental realization of such systems.