A novel electric current sensor employing twisted optical fibers

Abstract

Optical fiber current sensors have certain privileges that the traditional sensors couldn't support. However, when the fiber is deployed, a large degree of linear birefringence is induced in the fiber. This induced birefringence significantly reduces the sensitivity of the system and quenches the weak Faraday effect signal. We demonstrate that twisted the single mode fiber before it is annealed can largely eliminates the residual linear birefringence. It dramatically improves the possibility to employ the twisted single mode fiber that intrinsically had large residual linear birefringence for constructing an optical twisted electric current sensor. We design a new electric current sensor employing the twisted single mode optical fiber. This sensing system has been verified with good performance. The minimum detectable current was measured to be 1 A and the maximum measurable current up to 2kA with linearity lower than 0.1%, and dynamic range approaches 40 dB. Because of the advantages of high sensitivity, considerable wide dynamic range, and free from electric shock, this novel optic electric current sensor may open a new era in the applications of the electric power system.