  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 H$^{13}$CN are provided to
understand the impact of nonlinearity on spectroscopic measurements.
