A sensitive open-path gas sensor employing a continuous-wave (CW) distributed feedback (DFB) quantum cascade laser (QCL) and direct absorption spectroscopy (DAS) was demonstrated for simultaneously measurements of atmospheric CO and N₂O. Two interference free absorption lines located at 2190.0175 cm^-1 and 2190.3498 cm^-1 were selected for CO and N₂O concentration measurements, respectively. The Allan variance analysis technique was performed to investigate the long-term performance of the QCL sensor system. The results indicate that a detection limit of 9.92 ppb for CO and 7.7 ppb for N₂O with 1-s integration time were achieved, which can be further improved to 1.5 ppb and 1.1 ppb by increasing the average time up to 80 s.

Date Published: 10 February 2017
PDF: 5 pages
Proc. SPIE 10250, International Conference on Optical and Photonics Engineering (icOPEN 2016), 1025020 (10 February 2017); doi: 10.1117/12.2266820

Published in SPIE Proceedings Vol. 10250:
International Conference on Optical and Photonics Engineering (icOPEN 2016)
Anand Krishna Asundi; Xiyan Huang; Yi Xie, Editor(s)