Molecular dispersion spectroscopy for chemical sensing using chirped mid-infrared quantum cascade laser

Gerard Wysocki, Damien Weidmann

Research output: Contribution to journalArticlepeer-review

109 Scopus citations

Abstract

A spectroscopic method of molecular detection based on dispersion measurements using a frequency-chirped laser source is presented. An infrared quantum cascade laser emitting around 1912 cm-1 is used as a tunable spectroscopic source to measure dispersion that occurs in the vicinity of molecular ro-vibrational transitions. The sample under study is a mixture of nitric oxide in dry nitrogen. Two experimental configurations based on a coherent detection scheme are investigated and discussed. The theoretical models, which describe the observed spectral signals, are developed and verified experimentally. The method is particularly relevant to optical sensing based on mid-infrared quantum cascade lasers as the high chirp rates available with those sources can significantly enhance the magnitude of the measured dispersion signals. The method relies on heterodyne beatnote frequency measurements and shows high immunity to variations in the optical power received by the photodetector.

Original languageEnglish (US)
Pages (from-to)26123-26140
Number of pages18
JournalOptics Express
Volume18
Issue number25
DOIs
StatePublished - Dec 6 2010

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics

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