Abstract

The Faraday effect is an excellent method with which to measure electric current in certain applications. Electric current sensors for utilities can be constructed using magneto-optic sensor material which may be at high potential. Diamagnetic Faraday materials are particularly attractive because their Verdet constants are not temperature dependent. However, optical birefringence interferes with the accurate measurement of the Faraday rotation. Previous attempts to construct magneto-optic current transducers (MOCTs) have dealt with the birefringence by: (1) neglecting it; (2) actively compensating for it; or (3) twisting the fiber to swamp the linear birefringence with circular birefringence. These difficulties are compounded because the birefringence often varies strongly with temperature.

© 1988 Optical Society of America