Quantum theory of a two-mode open-cavity laser

TL;DR

This paper develops a quantum theoretical framework for a two-mode open-cavity laser, revealing how collective modes form and behave depending on cavity openness, with implications for understanding random laser systems.

Contribution

It introduces a quantum model for two-mode open-cavity lasers, highlighting the formation of a collective lasing mode influenced by cavity openness.

Findings

A collective mode emerges above the lasing threshold.

The behavior of the lasing mode depends explicitly on cavity openness.

The model provides insights relevant to random laser systems.

Abstract

We develop the quantum theory of an open-cavity laser assuming that only two modes compete for gain. We show that the modes interact to build up a collective mode that becomes the lasing mode when pumping exceeds a threshold. This collective mode exhibits all the features of a typical laser mode, whereas its precise behavior depends explicitly on the openness of the cavity. We approach the problem by using the density-matrix formalism and derive the master equation for the light field. Our results are of particular interest in the context random laser systems.