title: Faraday rotation spectroscopy based on permanent magnets for sensitive detection of oxygen at atmospheric conditions.
abstract: 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.
authors: Electrical Engineering Department, Princeton University, Princeton, New Jersey 08544, USA.
authors: Brian
authors: B
authors: Brumfield
authors: Gerard
authors: G
authors: Wysocki