Gas temperature and concentration detection via using a high-coherence dual comb laser

A high-coherence dual comb laser with locked repetition frequency and offset frequency of the carrier envelope is introduced in this work for gas parameter detection. In the dual comb laser, interferograms are collected and the frequency jittering are corrected for spectrum extraction of high signal to noise ratios. An intensity disturbance immune multispectral fitting method is introduced to obtain the gas temperature and concentration from measured absorption spectra with virtual baseline removal. Water vapor temperature and concentration in an open laser path were measured at a time resolution of 1 s and the relative deviations between the average temperature and the thermometer reading were 1.5%-2.4%. The developed dual comb laser and intensity disturbance immune multi-spectral fitting method yielded robust and reliable measurements on gas parameters.