Temperature Compensation of Optical Fiber Current Sensors With a Static Bias

Temperature cross-sensitivity is the main obstacle to the practical application of fiber current sensors based on the garnet crystal Faraday rotator. In this paper, a temperature compensation method is proposed and experimentally demonstrated. By introducing an appropriate static bias to the sensor, temperature compensation can be realized by simply measuring the Faraday rotation angles of the total field and the bias field. Experimental results show that the maximum relative error of the sensor is reduced from ±8.0% to ±2.0% in the temperature range of −20 °C to 60 °C after the application of the proposed method. After the correction of the nonlinearity of the Faraday crystal, the error is further reduced to be within ±1.0% in the whole temperature range. In common environmental temperature range, the maximum relative variation is within about ±0.5%. With the proposed method, AC signals can be continuously measured with temperature compensation in real-time. The fiber sensor with the proposed method can be used for metering or protection purpose in high-voltage power transmission systems.