Photon Bose-Einstein condensation and lasing in semiconductor cavities

TL;DR

This paper reviews the theoretical understanding of photon Bose-Einstein condensation and lasing in semiconductor cavities, comparing regimes, thresholds, and fluctuations, and highlighting the challenges in observing BEC in semiconductors.

Contribution

It provides a comprehensive theoretical comparison between photon BEC and lasing in semiconductor cavities, clarifying conditions and thresholds for each regime.

Findings

Photon BEC in semiconductors remains elusive despite theoretical frameworks.

Thermalisation and lasing thresholds are distinctly defined and compared.

System fluctuations differ significantly between BEC and lasing regimes.

Abstract

Photon Bose-Einstein condensation and photon thermalisation have been largely studied with molecular gain media in optical cavities. Their observation with semiconductors has remained elusive despite a large body of experimental results and a very well established theoretical framework. We use this theoretical framework as a convenient platform to revisit photon Bose-Einstein condensation in the driven-dissipative regime and compare with the lasing regime. We discuss the thermalisation figures of merit and the different experimental procedures to asses thermalization. We compare the definitions of lasing and condensation thresholds. Finally, we explore the fluctuations of the system and their relation to the different regimes.