LAUSR

Purpose This paper aims to provide a sensor for fast, sensitive and selective ethylene (C2H4) concentration measurements. Design/methodology/approach The paper developed a sensor platform based on tunable laser absorption spectroscopy with a 3,266-nm interband cascade laser (ICL) as an optical source and a hollow waveguide (HWG) as a gas cell. The ICL wavelength was scanned across a C2H4 strong fundamental absorption band, and an interference-free C2H4 absorption line located at 3,060.76 cm−1 was selected. Wavelength modulation spectroscopy with the second harmonic detection (WMS-2f) technique was used to improve the sensitivity. Furthermore, the HWG gas cell can achieve a long optical path in a very small volume to improve the time response. Findings The results show excellent linearity of the measured 2f signal and the C2H4 concentration with a correlation coefficient of 0.9997. Also, the response time is as short as about 10 s. The Allan variance analysis indicates that the detection limit can achieve 53 ppb with an integration time of 24 s. Practical implications The ethylene sensor has many meaningful applications in environmental monitoring, industrial production, national security and the biomedicine field. Originality/value The paper provides a novel sensor architecture which can be a versatile sensor platform for fast and sensitive trace-gas detection in the mid-infrared region.