Phase diagram for injection locking a superradiant laser

TL;DR

This paper explores how a superradiant laser responds to external driving, revealing two types of synchronization and mapping their behavior in a phase diagram through experiments and theory.

Contribution

It provides the first detailed phase diagram for injection locking in superradiant lasers, combining experimental results with theoretical modeling.

Findings

Identification of attractive and repulsive synchronization regimes

Experimental validation of the phase diagram predictions

Explanation of repulsive behavior via a three-dimensional atomic spin model

Abstract

We experimentally and theoretically study the response of a superradiant or bad-cavity laser to an applied coherent drive. We observe two forms of synchronization (injection locking) between the superradiant ensemble and the applied drive: one attractive and one repulsive in nature. We explain the region of repulsion as arising from the higher three-dimensional description of the atomic spin state that stores the laser coherence in a superradiant laser, as opposed to a two-parameter description of the electric field in a traditional good-cavity laser. We derive a phase diagram of predicted behavior and experimentally measure the response of the system across various trajectories therein.