Accession Number : ADA409236


Title :   Photonic Magnetic Field Sensor


Corporate Author : VISIDYNE INC BURLINGTON MA


Personal Author(s) : Wyntjes, Geert


Full Text : http://www.dtic.mil/dtic/tr/fulltext/u2/a409236.pdf


Report Date : 25 Feb 2002


Pagination or Media Count : 7


Abstract : Small, in-line polarization rotators or isolators to reduce feedback in fiber optic links can be the basis for excellent magnetic field sensors. Based on the giant magneto-optical (GMO) or Faraday effect in iron garnets, they with a magnetic field of a few hundred Gauss, (20 mT) for an interaction length for an optical beam of a few millimeters achieve a polarization rotation or phase shift of 45 deg (1/8 cycle). When powered by a small laser diode, with the induced linear phase shift recovered at the shot noise limit, we have demonstrated sensitivities at the 3.3 nT/Hz1/2 level for frequencies from 1 Hz to frequencies into the high kHz range. Through further improvements; an increase in interaction length, better materials and by far the greatest factor, the addition of a flux concentrator, sensitivities at the pT/Hz1/2 level appear to be within reach. We will detail such a design and discuss the issues that may limit achieving these goals.


Descriptors :   *MAGNETIC FIELDS , *MAGNETIC DETECTORS , FIBER OPTICS , POLARIZATION , PHOTONICS , FEEDBACK , FARADAY EFFECT , SHOT NOISE , DIODE LASERS


Subject Categories : Magnetic & Electric Fld Detection & Detectors


Distribution Statement : APPROVED FOR PUBLIC RELEASE