Nonlinear effects in random lasers

TL;DR

This paper explores the nonlinear effects in random lasers, showing that phenomena like mode competition and wave-mixing occur more prominently than in conventional lasers, especially at high pumping rates.

Contribution

It extends the understanding of multimode behavior in random lasers, highlighting the significance of nonlinear effects and mode interactions in complex, open systems.

Findings

Nonlinear effects such as mode competition are observed in random lasers.

These effects are more pronounced due to the openness and complexity of the modes.

Behavior similar to conventional lasers is confirmed in the multimode regime.

Abstract

Recent numerical and theoretical studies have demonstrated that the modes at threshold of a random laser are in direct correspondence with the resonances of the same system without gain, a feature which is well known in a conventional laser but which was not known until recently for a random laser. This paper presents numerical results, which extend such studies to the multimode regime that takes place when the pumping rate is progressively increased above threshold. Behavior that is already known in standard lasers, such as mode competition and nonlinear wave-mixing, are shown to also take place in random lasers thus reinforcing their recent modal description. However, due to the complexity of the laser modes and to the openness of such lasers, which requires large external pumping to compensate for strong loss, one observes that these effects are more pronounced than in a conventional laser.