Optical Magnetic Field Sensor Based on Electrogyratory and Electrooptic Compensation in Single Quartz Crystal

An optical magnetic field sensor based on electrogyratory and electrooptic compensation is proposed and experimentally demonstrated. Besides natural birefringence and optical activity, single quartz crystal simultaneously exhibits the magnetooptical Faraday effect, electrooptic Pockels effect, electrogyratory effect, and so on. For the intensity-modulated light sensing signal, the Faraday rotation angle can be compensated by both electrogyratory angle and electrooptic phase retardation. The 50-Hz ac magnetic flux density has been measured within 267 Gs by using a block of single quartz crystal, and typical compensating voltage is about ~ 0.725V·Gs
^-1
. Advantages of the proposed magnetic field sensor mainly include closed-loop optical measurement of magnetic field or current, low compensating voltage, moderate temperature dependence of electrooptic and electrogyratory effects, a solid sensing unit, and low cost.