Controlling nonlinear interaction in a many-mode laser by tuning disorder

TL;DR

This paper introduces a novel method to control nonlinear modal interactions in a many-mode laser by tuning disorder through phase fluctuations, enabling precise manipulation of mode structures and suppression of modal competition.

Contribution

The study demonstrates a new approach to control lasing modes via random phase fluctuations, providing a flexible platform for exploring many-body physics in laser systems.

Findings

Decreasing phase fluctuation scale fragments transverse modes.

Reduced spatial overlap suppresses modal competition.

Enhanced mode lasing with increased disorder tunability.

Abstract

A many-mode laser with nonlinear modal interaction could serve as a model system to study many-body physics. However, precise and continuous tuning of the interaction strength over a wide range is challenging. Here, we present a unique method for controlling lasing mode structures by introducing random phase fluctuation to a nearly degenerate cavity. We show numerically and experimentally that as the characteristic scale of phase fluctuation decreases by two orders of magnitude, the transverse modes become fragmented and the reduction of their spatial overlap suppresses modal competition for gain, allowing more modes to lase. The tunability, flexibility and robustness of our system provides a powerful platform for investigating many-body phenomena.