Photon noise in a random laser amplifier with fluctuating properties

TL;DR

This paper investigates how fluctuations in photocounts from a disordered amplifying medium reveal information about its properties, linking photocount variance to the medium's conductance and enabling non-invasive probing of such media.

Contribution

It establishes a direct connection between photocount fluctuations and the medium's conductance, offering a novel method to analyze amplifying disordered media through ASE statistics.

Findings

Photocount fluctuations encode information about medium properties.

Variance of fluctuations relates to the dimensionless conductance g.

Proposes non-invasive probing method for disordered media.

Abstract

We study fluctuations of the number of photocounts measured by an ideal photodetector illuminated by light scattered in an amplifying disordered medium, below the threshold for random lasing. We show that the variance of fluctuations and their correlation function carry information about fluctuating properties of the medium. A direct link is established between the fluctuations of the number of photocounts due to the amplified spontaneous emission (ASE) and the dimensionless conductance g of the medium. Our results suggest a possibility of probing amplifying disordered media by analyzing statistics of their ASE, without illuminating them from outside by a probe beam.