Open AccessFaraday rotation spectroscopy based on permanent magnets for sensitive detection of oxygen at atmospheric conditions
Author(s) -
Brian E. Brumfield,
Gerard Wysocki
Publication year - 2012
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.20.029727
Subject(s) - faraday effect , optics , physics , spectroscopy , polarization (electrochemistry) , magnet , faraday rotator , laser , wavelength , time delay and integration , faraday cage , rotation (mathematics) , materials science , magnetic field , chemistry , computer science , quantum mechanics , artificial intelligence
A low-power Faraday rotation spectroscopy system that uses permanent rare-earth magnets has been developed for detection of O₂ at 762 nm. The experimental signals are generated using laser wavelength modulation combined with a balanced detection scheme that permits quantum shot noise limited performance. A noise equivalent polarization rotation angle of 8 × 10⁻⁸ rad/Hz¹/² is estimated from the experimental noise, and this agrees well with a theoretical model based on Jones calculus. A bandwidth normalized minimum detection limit to oxygen of 6 ppmv/Hz¹/² with an ultimate minimum of 1.3 ppmv at integration times of ~1 minute has been demonstrated.