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.
@article{arxiv.1303.7138,
title = {Unequivocal differentiation of coherent and chaotic light through interferometric photon correlation measurements},
author = {Armand Lebreton and Izo Abram and Rémy Braive and Isabelle Sagnes and Isabelle Robert-Philip and Alexios Beveratos},
journal= {arXiv preprint arXiv:1303.7138},
year = {2015}
}