Strong light-matter coupling in the presence of lasing

TL;DR

This paper revises the criteria for strong light-matter coupling in cavity-QED systems, especially under lasing conditions, demonstrating the coexistence of strong coupling and lasing through theory and experiments.

Contribution

It introduces a generalized criterion for strong coupling that accounts for stimulated emission and higher Jaynes-Cummings states, supported by experimental validation.

Findings

Modified vacuum-Rabi splitting in lasing conditions

Demonstration of strong coupling and lasing coexistence

Generalized criterion applicable to driven dissipative systems

Abstract

The regime of strong light-matter coupling is typically associated with weak excitation. With current realizations of cavity-QED systems, strong coupling may persevere even at elevated excitation levels sufficient to cross the threshold to lasing. In the presence of stimulated emission, the vacuum-Rabi doublet in the emission spectrum is modified and the established criterion for strong coupling no longer applies. We provide a generalized criterion for strong coupling and the corresponding emission spectrum, which includes the influence of higher Jaynes-Cummings states. The applicability is demonstrated in a theory-experiment comparison of a few-emitter quantum-dot--micropillar laser as a particular realization of the driven dissipative Jaynes-Cummings model. Furthermore, we address the question if and for which parameters true single-emitter lasing can be achieved, and provide evidence for the coexistence of strong coupling and lasing in our system in the presence of background emitter contributions.