The glassy random laser: replica symmetry breaking in the intensity fluctuations of emission spectra

TL;DR

This paper introduces a new overlap parameter to analyze intensity fluctuations in random lasers, linking it to replica symmetry breaking in spin-glass models, and validates it with experimental data.

Contribution

It establishes a theoretical framework connecting intensity fluctuation overlaps with replica symmetry breaking, providing a novel way to interpret random laser spectra.

Findings

Replica symmetry breaking occurs at high pumping or low temperature.

The overlap parameter identifies the laser transition in random media.

The theory matches recent experimental measurements.

Abstract

The behavior of a newly introduced overlap parameter is analyzed, measuring the correlation between intensity fluctuations of waves in random media in different physical regimes, with varying amount of disorder and non-linearity. Its relationship is established to the standard Parisi overlap order parameter in replica theory for spin-glasses. In the complex spherical spin-glass model, describing the onset and behavior of random lasers, replica symmetry breaking in the intensity fluctuation overlap is shown to occur at high pumping or low temperature. This order parameter identifies the laser transition in random media and describes its glassy nature in terms of emission spectra data, the only data so far accessible in random laser measurements. The theoretical analysis is, eventually, compared to recent intensity fluctuation overlap measurements demonstrating the validity of the theory and providing a straightforward interpretation of different spectral behaviors in different random lasers.