Presence of temporal dynamical instabilities in topological insulator lasers

TL;DR

This paper investigates whether topological insulator lasers, which guide light along protected edge states, are immune to dynamical instabilities and finds that they are susceptible under realistic conditions.

Contribution

The study demonstrates that chiral edge states in topological insulator lasers are not immune to dynamical instabilities in realistic semiconductor class-B models.

Findings

Chiral edge states can exhibit dynamical instabilities.

Instabilities occur under realistic experimental parameters.

Topological protection does not guarantee stability.

Abstract

Topological insulator lasers are a newly introduced kind of lasers in which light snakes around a cavity without scattering. Like for an electron current in a topological insulator material, a topologically protected lasing mode travels along the cavity edge, steering neatly around corners and imperfections without scattering or leaking out. In a recent experiment, topological insulator lasers have been demonstrated using a square lattice of coupled semiconductor microring resonators with a synthetic magnetic field. However, laser arrays with slow population dynamics are likely to show dynamical instabilities in a wide range of parameter space corresponding to realistic experimental conditions, thus preventing stable laser operation. While topological insulator lasers provide an interesting mean for combating disorder and help collective oscillation of lasers at the edge of the lattice, it is not clear whether chiral edge states are immune to dynamical instabilities. In this work we consider a realistic model of semiconductor class-B topological insulator laser and show that chiral edge states are not immune to dynamical instabilities.