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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Scopus citations

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-1 range 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.

Original languageEnglish (US)
Title of host publicationInfrared, Mid-IR, and Terahertz Technologies for Health and the Environment II
DOIs
StatePublished - 2007
Externally publishedYes
EventInfrared, Mid-IR, and Terahertz Technologies for Health and the Environment II - Boston, MA, United States
Duration: Sep 10 2007Sep 10 2007

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume6760
ISSN (Print)0277-786X

Conference

ConferenceInfrared, Mid-IR, and Terahertz Technologies for Health and the Environment II
Country/TerritoryUnited States
CityBoston, MA
Period9/10/079/10/07

Keywords

  • Infrared spectroscopy
  • Quantum cascade laser
  • Tunable laser

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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