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/get-tr-doc/pdf?AD=ADA409236


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 AND DETECTORS


Distribution Statement : APPROVED FOR PUBLIC RELEASE