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Proceedings Paper

Measurement of broad absorption features using a tunable external cavity quantum cascade laser
Author(s): Mark C. Phillips; Tanya L. Myers; Michael D. Wojcik; Bret D. Cannon; Matthew S. Taubman; David C. Scott
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Paper Abstract

We demonstrate the use of a tunable external cavity quantum cascade laser system for measurement of broad absorption features in the mid-infrared spectral region. The thermoelectrically cooled external cavity laser was tuned over a 65 cm-1range centered at 8.7 microns using stepper motor control. Pulsing the laser at a high duty cycle provided 2-4.5 mW average output power over the tuning range, and enabled phase-sensitive detection of amplitude-modulated signals. We used the laser system to measure the absorption spectra of Freon-125 using a Herriott cell. In addition, the absorption spectrum of water in the laboratory air was measured. The measurements showed excellent agreement with reference spectra, in both wavelength and amplitude. The measured scan resolution of 0.14 cm-1 is suitable for measurement of the absorption features of complex molecules as well as simple molecules with atmospherically broadened lines. We discuss the limits to the scan resolution due to effects of spectral chirp and mode-hops during pulsed operation.

Paper Details

Date Published: 25 September 2007
PDF: 11 pages
Proc. SPIE 6760, Infrared, Mid-IR, and Terahertz Technologies for Health and the Environment II, 676003 (25 September 2007); doi: 10.1117/12.732616
Show Author Affiliations
Mark C. Phillips, Pacific Northwest National Lab. (United States)
Tanya L. Myers, Pacific Northwest National Lab. (United States)
Michael D. Wojcik, Pacific Northwest National Lab. (United States)
Bret D. Cannon, Pacific Northwest National Lab. (United States)
Matthew S. Taubman, Pacific Northwest National Lab. (United States)
David C. Scott, Pacific Northwest National Lab. (United States)


Published in SPIE Proceedings Vol. 6760:
Infrared, Mid-IR, and Terahertz Technologies for Health and the Environment II
Alexey A. Belyanin; Rebekah A. Drezek; Claire Gmachl, Editor(s)

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