Statistical studies of random lasing modes and amplified spontaneous emission spikes in weakly scattering systems

TL;DR

This study compares the spectral properties of lasing modes and spontaneous emission in weakly scattering systems, revealing distinct physical mechanisms and the influence of local gain on mode selection.

Contribution

It provides the first detailed statistical analysis of lasing modes versus spontaneous emission spikes in weakly scattering media, highlighting the impact of local excitation.

Findings

Spectral correlation functions differ significantly between lasing modes and spontaneous emission.

Local gain reduces the number of potential lasing modes even without reabsorption.

Lasing modes are highly influenced by local feedback and differ from passive quasimodes.

Abstract

We measured the ensemble-averaged spectral correlation functions and statistical distributions of spectral spacing and intensity for lasing modes in weakly scattering systems, and compared them to those of the amplified spontaneous emission spikes. Their dramatic differences illustrated the distinct physical mechanisms. Our numerical simulation revealed that even without reabsorption the number of potential lasing modes might be greatly reduced by local excitation of a weakly scattering system. The lasing modes could be drastically different from the quasimodes of the passive system due to selective amplification of the feedback from the scatterers within the local gain region.