VCSEL based Faraday rotation spectroscopy at 762nm for battery powered trace molecular oxygen detection

Stephen So, Gerard Wysocki

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


Faraday Rotation Spectroscopy (FRS) is a polarization based spectroscopic technique which can provide higher sensitivity concentration measurements of paramagnetic gases and free radicals than direct absorption spectroscopic techniques. We have developed sensor systems which require only 0.2W to perform TDLAS (tunable diode laser absorption spectroscopy), and can additionally be quickly duty cycled, enabling operation in wireless sensor networks of laser-based trace gas sensors We adapted our integrated TDLAS electronics to perform FRS in a compact and more sensitive system for quantification of molecular oxygen (O2) using a 762.3nm VCSEL in the A band. Using an AC magnetic field, we demonstrate detector noise dominated performance, achieving 2.1×10-6/Hz1/2 equivalent detectable fractional absorption and a minimum detection limit of 462 ppmv O2 in 1 second in a 15cm path. At longer paths and integration times, such a sensor will enable oxygen measurements at biotic respiration levels (<1ppmv) to measure CO2 - O2 exchange for mapping natural exchange of greenhouse gases. Potential improvement of detection limits by increasing various system performance parameters is described.

Original languageEnglish (US)
Title of host publicationVertical-Cavity Surface-Emitting Lasers XIV
StatePublished - 2010
EventVertical-Cavity Surface-Emitting Lasers XIV - San Francisco, CA, United States
Duration: Jan 27 2010Jan 28 2010

Publication series

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


OtherVertical-Cavity Surface-Emitting Lasers XIV
Country/TerritoryUnited States
CitySan Francisco, CA

All Science Journal Classification (ASJC) codes

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


Dive into the research topics of 'VCSEL based Faraday rotation spectroscopy at 762nm for battery powered trace molecular oxygen detection'. Together they form a unique fingerprint.

Cite this