Nonlinear Dynamics in Semiconductor Lasers 2023 - Abstract

Mertenskötter, Lutz

Bayesian estimation of laser linewidth from delayed self-heterodyne measurements

Self-heterodyne beat note measurements are widely used for the experimental characterisation of the frequency noise power spectral density (FN-PSD) and the spectral linewidth of lasers. The measured data, however, must be corrected for the transfer function of the experimental setup. The standard approach disregards the detector noise and thereby induces reconstruction artefacts in the reconstructed FN-PSD. We present a Bayesian estimation approach, that takes into account the transfer function, as well as the detector noise in a statistical model for the measured PSDs. This model produces the correct distributions of the the PSD at all frequencies and only needs a model for its mean to be parameterised. Our method yields excellent results even in the presence of strong detector noise, where the intrinsic linewidth plateau is obscured by detector noise. The approach is demonstrated for simulated time series from a stochastic laser model including 1/ 𝑓 -type noise. Finally we use parametric Wiener filters to generate artefact free reconstructions of the PSDs using the estimated parameters.