Injection locking of quantum dot microlasers operating in the few photon regime

TL;DR

This paper explores injection locking in quantum dot microlasers operating in the few-photon regime, revealing simultaneous stable oscillations at master and slave frequencies due to cavity-enhanced spontaneous emission.

Contribution

It provides both experimental and theoretical insights into injection locking phenomena in quantum dot microlasers within the cQED regime, highlighting unique emission characteristics.

Findings

Demonstration of frequency and phase locking in QD microlasers

Observation of simultaneous master and slave emission with distinct coherence properties

Explanation of behavior via cavity-enhanced spontaneous emission and low photon numbers

Abstract

We experimentally and theoretically investigate injection locking of quantum dot (QD) microlasers in the regime of cavity quantum electrodynamics (cQED). We observe frequency locking and phase-locking where cavity enhanced spontaneous emission enables simultaneous stable oscillation at the master frequency and at the solitary frequency of the slave microlaser. Measurements of the second-order autocorrelation function prove this simultaneous presence of both master and slave-like emission, where the former has coherent character with $g^{(2)}(0)=1$ while the latter one has thermal character with $g^{(2)}(0)=2$. Semi-classical rate-equations explain this peculiar behavior by cavity enhanced spontaneous emission and a low number of photons in the laser mode.