Fiber Optic Current Sensor Based on Special Spun Highly Birefringent Fiber

A fiber optic current sensor based on a polarization-rotated reflected interferometer has been constructed. A special spun highly birefringent fiber is designed and achieved for the sensor by heating and spinning commercial linearly birefringent fiber. In contrast with conventional fibers, the fiber integrates a function of a quarter wave plate. Particularly, fabricating and working principle of the current sensor head using the fiber are expounded. The sensor achieves an accuracy with 0.5% and good linearity shown in temperature dependence (a temperature drift of 0.008%/
$^{\circ}{\rm C}$
) over a temperature range 40
$^{\circ}{\rm C}$
–70
$^{\circ}{\rm C}$
. Further, under simple temperature compensation, the sensor accuracy is within
${\pm}{0.1\%}$
over in a wide range of current and temperature ranges.