Vibration-insensitive fiber-optic current sensor.

The measurement of the electric current with an optical fiber sensor can be made insensitive to external vibrations that act on the leading fiber by using a circuit involving a mirrored Faraday rotator and a highly twisted low-birefringence fiber. A description of the optical configuration as well as our first experimental results are presented. The circuit gives a passive compensation of the disturbances with a measured rejection of the order of 30 dB while maintaining the correct sensitivity to the measurement of the Faraday effect.