Open AccessRemote open-path cavity-ringdown spectroscopic sensing of trace gases in air, based on distributed passive sensors linked by km-long optical fibers
Author(s) -
Yabai He,
Huangzhao Wei,
Ruifeng Kan,
Jianguo Liu,
Wenqing Liu,
J. Hill,
Ian M. Jamie,
Brian J. Orr
Publication year - 2014
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.22.013170
Subject(s) - trace gas , optics , materials science , brillouin scattering , optical fiber , optical path , interference (communication) , parts per notation , optoelectronics , remote sensing , physics , telecommunications , meteorology , computer science , geology , channel (broadcasting) , quantum mechanics
A continuous-wave, rapidly swept cavity-ringdown spectroscopic technique has been developed for localized atmospheric sensing of trace gases at remote sites. It uses one or more passive open-path optical sensor units, coupled by optical fiber over distances of >1 km to a single transmitter/receiver console incorporating a photodetector and a swept-frequency diode laser tuned to molecule-specific near-infrared wavelengths. Ways to avoid interference from stimulated Brillouin scattering in long optical fibers have been devised. This rugged open-path system, deployable in agricultural, industrial, and natural atmospheric environments, is used to monitor ammonia in air. A noise-limited minimum detectable mixing ratio of ~11 ppbv is attained for ammonia in nitrogen at atmospheric pressure.