Abstract

Fiber-optic magnetic sensors and current sensors for low level detections have been developed utilizing the magnetostrictive effect.^{(1), (2)} Weak DC magnetic field detections are very important, but distributed sensings are of even greater value in certain fields such as geomagnetic surveying. However, only a limited amount of work on DC detection has been reported⁽³⁾ Reported DC sensors are relatively complex, utilizing the non-linear nature of magnetostriction with a biasing coil situated around the ferromagnetic sensing element. To solve the complexity problem, a novel AC/DC magnetic sensor has very recently been proposed⁽⁴⁾ utilizing the Lorentzian force with an interferometric configuration. This paper reports advanced applications to weaker magnetic field and low level electric current measurements with this sensor. DC magnetic field and current sensors of this type are relatively simple and yet can easily be used in multiplexed systems employing the FDM ⁽⁵⁾ technique.

© 1988 Optical Society of America