Rapid and precise partial pressure measurement of multiple gas species with mid-infrared electro-optic dual-comb spectroscopy

Abstract In order to overcome the shortcoming of the TDLAS method, a partial pressure measurement method based on dual comb spectroscopy is proposed. The comb-based partial pressure measurement system comes with excellent performance in nearly all criteria: high detection sensitivity, high measurement speed, and synchronous survey of multiple-gas partial pressures. The experimental system was built in the mid-infrared band of 88.42–90.10 THz with a spectral resolution of 54.5 MHz and used for partial pressure measurement of CH4 and C2H4. Two electro-optics (EO) optical frequency combs (OFC) with a repeat frequency of ～25 GHz are spectrally interpolated to increase spectral sampling ratio using an acousto-optic frequency shifter, so that they could be utilized for high-resolution gas sensing. The measurement result demonstrates the excellent performance of this system in partial pressure measurement. The deviation of the measurement results of two gases CH4 and C2H4 from the true value are about 3%. Moreover, once the gas absorption line strength is accurately calibrated, the accuracy of partial pressure measurement will be further improved.