Development of a tunable mid-IR difference frequency laser source for highly sensitive airborne trace gas detection |
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Authors: | Richter D Fried A Wert B P Walega J G Tittel F K |
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Institution: | (1) National Center for Atmospheric Research, 1850 Table Mesa Dr., Boulder, CO 80305, USA, US;(2) Rice Quantum Institute, Rice University, 6100 Main St. Houston, TX 77005, USA, US |
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Abstract: | The development of a compact tunable mid-IR laser system at 3.5 μm for quantitative airborne spectroscopic trace gas absorption
measurements is reported. The mid-IR laser system is based on difference frequency generation (DFG) in periodically poled
LiNbO3 and utilizes optical fiber amplified near-IR diode and fiber lasers as pump sources operating at 1083 nm and 1562 nm, respectively.
This paper describes the optical sensor architecture, performance characteristics of individual pump lasers and DFG, as well
as its application to wavelength modulation spectroscopy employing an astigmatic Herriott multi-pass gas absorption cell.
This compact system permits detection of formaldehyde with a minimal detectable concentration (1σ replicate precision) of
74 parts-per-trillion by volume (pptv) for 1 min of averaging time and was achieved using calibrated gas standards, zero air
background and rapid dual-beam subtraction. This corresponds to a pathlength-normalized replicate fractional absorption sensitivity
of 2.5×10-10 cm-1.
Received: 29 April 2002 / Published online: 21 August 2002
RID="*"
ID="*"Corresponding author. Fax: +1-303/497-1492, E-mail: dr@ucar.edu |
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Keywords: | PACS: 42 55 Wd 42 60 By 42 60 Jf 42 62 Fi 42 79 Nv |
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