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Applied Physics B

, Volume 75, Issue 2–3, pp 267–280 | Cite as

Rapidly swept, continuous-wave cavity ringdown spectroscopy with optical heterodyne detection: single- and multi-wavelength sensing of gases

  • Y. He
  • B.J. Orr

Abstract.

Spectroscopic sensing of gases can be performed with high sensitivity and photometric precision by cavity ringdown (CRD) absorption spectroscopy. Our cavity ringdown spectrometer incorporates continuous-wave (cw) tunable diode lasers, fibre-optic coupling and standard photonics and optical telecommunications components. It comprises a rapidly swept optical cavity in a single-ended optical heterodyne transmitter–receiver configuration, enabling optical absorption of gases to be recorded either as single-frequency scanned spectra or as simultaneous, multi-wavelength tailored spectra. By measuring weak near-infrared rovibrational spectra of carbon dioxide gas (CO2), with high resolution in the vicinity of 1.53 μm, we have realised a noise-limited absorption sensitivity of 2.5×10-9 cm-1 Hz-1/2. Analytical sensitivity limits (both actual and projected) and prospective gas-diagnostic applications are discussed. Our approach to cw-CRD spectroscopy offers high performance in a relatively simple, low-cost, compact instrument that is amenable to chemical analysis of trace gases in medical, agricultural, industrial and environmental situations.

PACS: 07.07.Df; 33.20.-t; 42.62.Fi 

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Copyright information

© Springer-Verlag 2002

Authors and Affiliations

  • Y. He
    • 1
  • B.J. Orr
    • 1
  1. 1.Department of Chemistry and Centre for Lasers & Applications, Macquarie University, Sydney, NSW 2109, AustraliaAU

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