Chiral states in coupled-lasers lattice by on-site complex potential

TL;DR

This paper introduces a method to control the chirality of laser arrays using on-site complex potentials, achieving nearly pure chiral states at exceptional points, resilient to noise and imperfections.

Contribution

The authors demonstrate a novel approach to induce and control chirality in large laser networks via local on-site complex potentials at exceptional points.

Findings

Chiral lasing states can be selectively stabilized.

Tuning to an exceptional point yields nearly pure chiral states.

The method is robust against noise and imperfections.

Abstract

The ability to control the chirality of physical devices is of great scientific and technological importance, from investigations of topologically protected edge states in condensed matter systems to wavefront engineering, isolation, and unidirectional communication. When dealing with large networks of oscillators, the control over the chirality of the bulk states becomes significantly more complicated and requires complex apparatus for generating asymmetric coupling or artificial gauge fields. Here we present a new approach for precise control over the chirality of a triangular array of hundreds of symmetrically-coupled lasers, by introducing a weak non-Hermitian complex potential, requiring only local on-site control of loss and frequency. In the unperturbed network, lasing states with opposite chirality (staggered vortex and staggered anti-vortex) are equally probable. We show that by tuning the complex potential to an exceptional point, a nearly pure chiral lasing state is achieved. While our approach is applicable to any oscillators network, we demonstrate how the inherent non-linearity of the lasers effectively pulls the network to the exceptional point, making the chirality extremely resilient against noises and imperfections.