Spatial and Spectral Mode-Selection Effects in Topological Lasers with Frequency-Dependent Gain

TL;DR

This paper develops a semiclassical theory for topological lasers with frequency-dependent gain, showing how spatial and spectral gain design can enable stable single-mode lasing in edge states of a Harper-Hofstadter lattice.

Contribution

It introduces a new theoretical framework for understanding mode selection in topological lasers with frequency-dependent gain, specifically in Harper-Hofstadter systems.

Findings

Designing gain distribution stabilizes single-mode lasing.

Spectral shaping of gain influences mode stability.

Implications for experimental realization of topological lasers.

Abstract

We develop a semiclassical theory of laser oscillation into a chiral edge state of a topological photonic system endowed with a frequency-dependent gain. As an archetypal model of this physics, we consider a Harper-Hofstadter lattice embedding population-inverted two-level atoms as gain material. We show that a suitable design of the spatial distribution of gain and of its spectral shape provides flexible mode selection mechanisms that can stabilize single-mode lasing into an edge state. Implications of our results for recent experiments are outlined.