Understanding Photodetection Nonlinearity In Dual-Comb Interferometry

The impact of photodetector nonlinearity on dual-comb spectrometers is described and compared to that of Michelson-based Fourier transform spectrometers (FTS). The optical sampling occurring in the dual-comb approach, being the key difference with FTS, causes optical aliasing of the nonlinear spectral artifacts. Measured linear and nonlinear interferograms are presented to validate the model. Absorption lines of (HCN)-C-13 are provided to understand the impact of nonlinearity on spectroscopic measurements. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement