Midinfrared Compressed Fourier-Transform Spectroscopy with an Optical Frequency Comb

Abstract

Broadband precision spectroscopy is an invaluable tool for high-fidelity species diagnostics as well as multispecies sensing in complex real-world environments. However, concurrent demands for broad spectral coverage and high spectral resolution present great challenges to both optical measurement systems and data acquisition and processing. We report methodological and experimental demonstration of a midinfrared direct optical frequency comb (OFC) spectrometer, using Fourier-transform spectroscopy (FTS) with a compressed sensing (CS) algorithm. Efficient data sampling and accurate spectral recovery are demonstrated with comb-teeth-resolving resolution of $0.0083\phantom{\rule{0.2em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ (250 MHz) over a spectral range of $300\phantom{\rule{0.2em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$. The ${v}_{3}$ band of ${\mathrm{CH}}_{4}$ is measured, and validated against conventional FTS results and theoretical calculations. Studies on the effect of compression ratio show that a compressed interferogram using as few as 2% of the regular sample points can effectively recover the high-resolution broadband spectrum with an accuracy of 1.9%. The developed diagnostic system bears promising potential for accurate, real-time, multispecies sensing that is pressingly needed for studying the dynamics of complex multicomponent systems.