AUTHOR=Xi Zhenhai , Zheng Kaiyuan , Zheng Chuantao , Zhang Haipeng , Song Fang , Li Chunguang , Ye Weilin , Zhang Yu , Wang Yiding , Tittel Frank K. 

TITLE=Near-Infrared Dual-Gas Sensor System for Methane and Ethane Detection Using a Compact Multipass Cell

JOURNAL=Frontiers in Physics

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2022.843171

DOI=10.3389/fphy.2022.843171

ISSN=2296-424X

ABSTRACT=<p>In this invited paper, a compact dense-pattern multipass cell-based near-infrared sensor system was demonstrated for detection of parts-per-billion in volume (ppbv)-level methane (CH<sub>4</sub>) and ethane (C<sub>2</sub>H<sub>6</sub>). The dimension size of the fabricated gas cell is 18.5 × 8 × 9 cm<sup>3</sup> with an absorption path length of 9.39 m. CH<sub>4</sub> measurement was realized within a spectral range of 6,046–6,048 cm<sup>−1</sup> and an absorption line of 6,046.95 cm<sup>−1</sup>. The spectral range for C<sub>2</sub>H<sub>6</sub> detection is 5,951–5,953 cm<sup>−1</sup> with an absorption line of 5,951.73 cm<sup>−1</sup>. Allan deviation analysis was used for evaluating the dual-gas sensing performance, and a detection limit of 78 ppbv for CH<sub>4</sub> and 190 ppbv for C<sub>2</sub>H<sub>6</sub> were achieved, respectively, with an averaging time of 0.8 s. Furthermore, CH<sub>4</sub> measurement in the indoor and outdoor atmosphere was both performed to verify the field sensing capability of the sensor system. Compared with two separate sensor systems for CH<sub>4</sub>/C<sub>2</sub>H<sub>6</sub> sensing, the proposed dual-gas sensor system using two near-infrared lasers and one multipass cell has the advantages of low-cost, compact-size without decreasing the selectivity and sensitivity.</p>