Single-Mode Fiber-Optic Sensor for High Currents

摘要

We are developing a pulsed current sensor that will be less intrusive than present sensors and that we hope will remain linear to much higher current levels. Polarized laser light is transmited by a low-birefringence, single mode optical fiber that encircles the current carrier. We observe the Faraday rotation of the polarization plane in the current-induced magnetic field. We have measured a Verdet constant of about 260 exp 0 /MA for 633 nm light in Lightwave Technologies, Inc., Model F1506C fiber, and we have detected currents of up to 12 MA in pulses 0.5 to 40 mu s long. Our major problems have involved signal noise from stray plasma light getting into the fiber and shock-induced birefringence that rotates the polarization slightly. Future plans are to try to Sagnac interferometer to reduce the sensitivity to shock waves. (ERA citation 08:042098)