Parity-time symmetric optical coupler with birefringent arms

TL;DR

This paper introduces a PT-symmetric optical coupler with birefringent arms, analyzing its linear and nonlinear behaviors, symmetry breaking, and bifurcations, revealing complex dynamics and phase transition phenomena.

Contribution

It models a realistic PT-symmetric optical system with birefringent waveguides, exploring stationary solutions, symmetry breaking, and bifurcation structures in both linear and nonlinear regimes.

Findings

Identification of PT symmetry breaking point

Existence of nonlinear solutions up to the phase transition

Observation of saddle-center bifurcations in solutions

Abstract

In this work, we propose a PT-symmetric coupler whose arms are birefringent waveguides as a realistic physical model which leads to a so-called quadrimer i.e., a four complex field setting. We seek stationary solutions of the resulting linear and nonlinear model, identifying its linear point of PT symmetry breaking and examining the corresponding nonlinear solutions that persist up to this point, as well as, so-called, ghost states that bifurcate from them. We obtain the relevant symmetry breaking bifurcations and numerically follow the associated dynamics which give rise to growth/decay even within the PT-symmetric phase. Our obtained stationary nonlinear solutions are found to terminate in saddle-center bifurcations which are analogous to the linear PT-phase transition.