Interband cascade laser-based sensor for ambient CH4

We demonstrate a mid-IR semiconductor laser-based absorption spectrometer for field measurements of ambient CH4. The field sensor uses a type II quantum cascade laser (or interband cascade laser, ICL) operating near 3.3 [micro]m to monitor a well-isolated line in the I1/23 fundamental band of CH4. T...

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Bibliographic Details
Published in:Optical engineering 2010-11, Vol.49 (11)
Main Authors: Sonnenfroh, David M, Wainner, Richard T, Allen, Mark G, Varner, Ruth K
Format: Article
Language:English
Subjects:
Absorption spectroscopy
Balancing
Cascade lasers
Indium arsenides
Lasers
Monitors
Semiconductors
Sensors
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Summary:We demonstrate a mid-IR semiconductor laser-based absorption spectrometer for field measurements of ambient CH4. The field sensor uses a type II quantum cascade laser (or interband cascade laser, ICL) operating near 3.3 [micro]m to monitor a well-isolated line in the I1/23 fundamental band of CH4. The ICL operates in cw mode at cryogenic temperatures. The sensor uses a multipass cell that provides an optical path of [approx]7 m with a 0.25-m base path. Thermoelectrically cooled InAs detectors are used along with balanced ratiometric detection to achieve a precision of 15 ppbv for a 60-s integration time. Several successful field demonstrations are carried out at sites maintained by the University of New Hampshire.
ISSN:0091-3286
DOI:10.1117/1.3498769