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Proceedings Paper

Pulsed quantum cascade laser based cavity ring-down and cavity enhanced spectroscopy for the detection of ethylene.
Author(s): J. Manne; W. Jäger; J. Tulip
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Paper Abstract

We investigated the use of a pulsed, distributed feedback (DFB) quantum cascade (QC) laser centered at 970 cm-1 in combination with cavity ring-down spectroscopy (CRDS) and cavity enhanced spectroscopic (CES) techniques for the detection of ethylene. In these techniques, the laser is coupled to a high-finesse cavity formed by high reflectivity mirrors. In the CRDS application, the laser frequency was tuned at a rate of ~0.071 cm-1/K by changing the heat sink temperature in the range between -20 and 50°C. For off-axis CES, the laser was excited with short current pulses (5-10 ns), and the pulse amplitude was modulated with an external current ramp which gave a frequency scan of ~0.3 cm-1. We utilized a demodulation approach followed by numerical filtering to improve the signal-to-noise ratio. Basic instrument performance and optimizations of the experimental parameters for sensitivity improvement are discussed. We demonstrated a detection limit of ~130 ppb with CRDS and ~15 ppb with off-axis CES for ethylene.

Paper Details

Date Published: 12 August 2008
PDF: 8 pages
Proc. SPIE 7099, Photonics North 2008, 709922 (12 August 2008); doi: 10.1117/12.804794
Show Author Affiliations
J. Manne, Univ. of Alberta (Canada)
W. Jäger, Univ. of Alberta (Canada)
J. Tulip, Univ. of Alberta (Canada)

Published in SPIE Proceedings Vol. 7099:
Photonics North 2008

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