Modeling and analysis on the sensing characteristic of fiber optical current transformer

The sensing characteristic of fiber optical current transformer(FOCT) is affected by linear birefringence. In this paper, evolution process of optical polarization is derived and linear birefringence's influence on sensing characteristic of FOCT is analyzed in essence. Phase difference of light field components during transmission process is resulted by wave vector's inequality in non-propagating direction. As a result, linear birefringence is created and optical rotation angle of FOCT is decreased. Calculation method of FOCT's optical rotation angle is realized with decoupling of Faraday effect and linear birefringence. By using COMSOL, sensing optical fiber's micro-element model of FOCT is established. Coupling of optical field and magnetic field is realized with finite element method. Besides, FOCT's optical rotation angle is obtained. Finally, experiment platform of FOCT is designed and set up. The correctness of the theoretical analysis is verified by the results of simulation and experiment.