Unequivocal differentiation of coherent and chaotic light through interferometric photon correlation measurements

TL;DR

This paper introduces a new interferometric photon correlation method to clearly distinguish between chaotic and coherent light, enabling precise laser output characterization.

Contribution

The authors develop and demonstrate a novel interferometric technique that unambiguously differentiates coherent light with amplitude fluctuations from chaotic light, improving laser diagnostics.

Findings

The method accurately identifies laser output as a coherent state with fluctuations.

It differentiates chaotic light from coherent light with high confidence.

Experimental validation on semiconductor nanolasers confirms the technique's effectiveness.

Abstract

We present a novel experimental technique that can differentiate unequivocally between chaotic light and coherent light with amplitude fluctuations, and thus permits to characterize unambiguously the output of a laser. This technique consists of measuring the second-order intensity cross-correlation at the outputs of an unbalanced Michelson interferometer. It is applied to a chaotic light source and to the output of a semiconductor nanolaser whose "standard" intensity correlation function above-threshold displays values compatible with a mixture of coherent and chaotic light. Our experimental results demonstrate that the output of such lasers is not partially chaotic but is indeed a coherent state with amplitude fluctuations.