Open AccessSensitive CH_4 detection applying quantum cascade laser based optical feedback cavity-enhanced absorption spectroscopy
Author(s) -
Norbert Lang,
U. Macherius,
M. Wiese,
H. Zimmermann,
J. Röpcke,
J. H. van Helden
Publication year - 2016
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.24.00a536
Subject(s) - quantum cascade laser , optics , laser , spectrometer , cascade , spectroscopy , absorption spectroscopy , materials science , tunable diode laser absorption spectroscopy , cavity ring down spectroscopy , attenuation coefficient , absorption (acoustics) , optical cavity , distributed feedback laser , optoelectronics , physics , chemistry , chromatography , quantum mechanics
We report on sensitive detection of atmospheric methane employing quantum cascade laser based optical feedback cavity-enhanced absorption spectroscopy (OF-CEAS). An instrument has been built utilizing a continuous-wave distributed feedback quantum cascade laser (cw-QCL) with a V-shaped cavity, a common arrangement that reduces feedback to the laser from non-resonant reflections. The spectrometer has a noise equivalent absorption coefficient of 3.6 × 10 -9 cm -1 Hz -1 / 2 for a spectral scan of CH 4 at 7.39 μm. From an Allan-Werle analysis a detection limit of 39 parts per trillion of CH 4 at atmospheric pressure within 50 s acquisition time was found.