A Trace C₂H₂ Detection Based on Near‐Infrared Dual‐Comb Spectroscopy

ABSTRACT To achieve low‐concentration measurement using near‐infrared dual‐comb spectroscopy (DCS), this study presents a trace C 2 H 2 detection using near‐infrared DCS. A multi‐pass gas cell is employed to extend the optical path length, improving the sensor's sensitivity. Signal post‐processing via interpolation method is applied to reduce noise and achieve a flatter dual‐comb. The sensor's sensitivity and transient characteristics are evaluated by selecting absorption lines at 6526.53, 6529.17, and 6531.78 cm −1 , with the experimental profile being well‐fitted by a Voigt function. The stability of the system is confirmed with a C 2 H 2 concentration of 200 ppm over a 2.5 h observation period, showing a stability better than 2.305 × 10 −2 . Allan variance analysis indicates an optimal integration time of 597 s, yielding a minimum detection limit of 6.15 × 10 −4 for absorbance and 350 ppb for concentration. Additionally, the detection of nine absorption lines demonstrates the multi‐peak measurement capability, with deviations ranging from 0.059% to 12.496%.