Heterodyne-enhanced Faraday rotation spectrometer

Yin Wang, Michal Nikodem, Jake Hoyne, Gerard Wysocki

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

4 Scopus citations


A novel heterodyne-enhanced Faraday rotation spectroscopic (H-FRS) system for trace gas detection of nitric oxide (NO) is demonstrated. The system is based on a quantum cascade laser emitting at ∼5.2 μm and a mercury cadmium telluride photodetector (both thermoelectrically cooled). The heterodyne detection is performed at 30MHz, where the laser relative intensity noise is significantly smaller than at low frequencies. With an implementation of active interferometer stabilization technique, the current system shows total noise level that is only 5.4 times above the fundamental shot-noise limit and the Faraday rotation angle sensitivity of 2.6 × 10 -8 rad/√Hz. The NO detection limit of 30.7 ppb-v/√Hz was achieved for the R(8.5)e NO transition using 100 Gauss magnetic field and 0.15 m optical path length.

Original languageEnglish (US)
Title of host publicationQuantum Sensing and Nanophotonic Devices IX
StatePublished - 2012
EventQuantum Sensing and Nanophotonic Devices IX - San Francisco, CA, United States
Duration: Jan 22 2012Jan 26 2012

Publication series

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


OtherQuantum Sensing and Nanophotonic Devices IX
Country/TerritoryUnited States
CitySan Francisco, CA

All Science Journal Classification (ASJC) codes

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


  • Faraday rotation spectroscopy
  • laser spectroscopy
  • optical heterodyne detection
  • quantum cascade laser
  • trace gas detection


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