Pump-power-driven mode switching in a microcavity device and its relation to Bose-Einstein condensation

TL;DR

This paper explores how pump power influences mode switching in a microcavity device, revealing a process akin to Bose-Einstein condensation of photons, with implications for understanding light coherence and mode competition.

Contribution

It demonstrates the mechanism behind mode switching driven by pump power and links it to Bose-Einstein condensation phenomena in a minimal photonic system.

Findings

Mode switching occurs via an intermediate phase with both modes emitting coherently.

Strong anticorrelations and superthermal fluctuations are observed during switching.

The switching mechanism is related to competition between gain and intermode kinetics.

Abstract

We investigate the switching of the coherent emission mode of a bimodal microcavity device, occurring when the pump power is varied. We compare experimental data to theoretical results and identify the underlying mechanism to be based on the competition between the effective gain on the one hand and the intermode kinetics on the other. When the pumping is ramped up, above a threshold the mode with the largest effective gain starts to emit coherent light, corresponding to lasing. In contrast, in the limit of strong pumping it is the intermode kinetics that determines which mode acquires a large occupation and shows coherent emission. We point out that this latter mechanism is akin to the equilibrium Bose-Einstein condensation of massive bosons. Thus, the mode switching in our microcavity device can be viewed as a minimal instance of Bose-Einstein condensation of photons. We, moreover, show that the switching from one cavity mode to the other occurs always via an intermediate phase where both modes are emitting coherent light and that it is associated with both superthermal intensity fluctuations and strong anticorrelations between both modes.