Infrared cavity ringdown and integrated cavity output spectroscopy for trace species monitoring

J. B. Paul, J. J. Scherer, A. O'Keefe, L. Lapson, J. G. Anderson, C. Gmachl, F. Capasso, A. Y. Cho

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


Although the ability of high finesse optical cavities to provide effective absorption path-lengths exceeding 10 km. has been known for quite some time, attempts to utilize this property for the purposes of high-resolution spectroscopy have often resulted in extremely complex experimental systems. Here, we demonstrate how off-axis optical paths through such cavities can be employed to produce relatively simple spectrometers capable of ultrasensitive absorption measurements. A proof-of-concept study using visible diode lasers has achieved a normalized absorption sensitivity of 1.8*10-10 cm-1Hz-1/2. Additionally, quantum cascade lasers have been employed to extend this method into the mid-infrared region, where sensitivities of 1.2*10-9 cm-1Hz-1/2 have been obtained.

Original languageEnglish (US)
Pages (from-to)1-11
Number of pages11
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 2001
Externally publishedYes

All Science Journal Classification (ASJC) codes

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


  • Absorption spectroscopy
  • Optical cavity
  • Quantum cascade laser
  • Trace-gas detection


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