Sensors (Nov 2021)

Quasi-Simultaneous Sensitive Detection of Two Gas Species by Cavity-Ringdown Spectroscopy with Two Lasers

  • Guosheng Ma,
  • Yabai He,
  • Bing Chen,
  • Hao Deng,
  • Ying Liu,
  • Xingping Wang,
  • Zhihao Zhao,
  • Ruifeng Kan

DOI
https://doi.org/10.3390/s21227622
Journal volume & issue
Vol. 21, no. 22
p. 7622

Abstract

Read online

We developed a cavity ringdown spectrometer by utilizing a step-scanning and dithering method for matching laser wavelengths to optical resonances of an optical cavity. Our approach is capable of working with two and more lasers for quasi-simultaneous measurements of multiple gas species. The developed system was tested with two lasers operating around 1654 nm and 1658 nm for spectral detections of 12CH4 and its isotope 13CH4 in air, respectively. The ringdown time of the empty cavity was about 340 µs. The achieved high detection sensitivity of a noise-equivalent absorption coefficient was 2.8 × 10−11 cm−1 Hz−1/2 or 1 × 10−11 cm−1 by averaging for 30 s. The uncertainty of the high precision determination of δ13CH4 in air is about 1.3‰. Such a system will be useful for future applications such as environmental monitoring.

Keywords