Strong Interactions in Multimode Random Lasers

TL;DR

This paper develops a rigorous theory for diffusive random lasers, revealing that strong modal interactions produce a uniformly spaced frequency spectrum, aligning with recent experimental findings.

Contribution

It introduces a new theoretical framework for diffusive random lasers, addressing their lack of resonator modes and explaining their multimode behavior.

Findings

DRLs exhibit strong modal interactions.

Lasing spectra are uniformly spaced.

Results agree with recent experiments.

Abstract

Unlike conventional lasers, diffusive random lasers (DRLs) have no resonator to trap light and no high-Q resonances to support lasing. Due to this lack of sharp resonances the DRL has presented a challenge to conventional laser theory. We present a theory able to treat the DRL rigorously, and provide results on the lasing spectra, internal fields and output intensities of DRLs. Typically DRLs are highly multimode lasers, emitting light at a number of wavelengths. We show that the modal interactions through the gain medium in such lasers are extremely strong and lead to a uniformly spaced frequency spectrum, in agreement with recent experimental observations.