Measurement of broad absorption features using a tunable external cavity quantum cascade laser

Mark C. Phillips; Tanya L. Myers; Michael D. Wojcik; Bret D. Cannon; Matthew S. Taubman; David C. Scott

doi:10.1117/12.732616

25 September 2007 Measurement of broad absorption features using a tunable external cavity quantum cascade laser

Mark C. Phillips, Tanya L. Myers, Michael D. Wojcik, Bret D. Cannon, Matthew S. Taubman, David C. Scott

Proceedings Volume 6760, Infrared, Mid-IR, and Terahertz Technologies for Health and the Environment II; 676003 (2007) https://doi.org/10.1117/12.732616
Event: Optics East, 2007, Boston, MA, United States

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.

Citation Download Citation

Mark C. Phillips, Tanya L. Myers, Michael D. Wojcik, Bret D. Cannon, Matthew S. Taubman, and David C. Scott "Measurement of broad absorption features using a tunable external cavity quantum cascade laser", Proc. SPIE 6760, Infrared, Mid-IR, and Terahertz Technologies for Health and the Environment II, 676003 (25 September 2007); https://doi.org/10.1117/12.732616

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