This Letter demonstrates the effect and elimination of alignment error in an optical fiber current sensor. An optical model is built to illustrate the effect of alignment error, which does not induce zero drift and has a large effect on output accuracy. The total alignment error and modulation angle of the polarization controller are defined as and , respectively. Parameter is equal to . An elimination method of the error is proposed, which corrects the angle to keep parameter at 90 deg. This method avoids the measurement of all splice angles separately. Its feasibility is shown by simulation results. In addition, the measurement method and conditions of parameter are presented. The final is about 90.24 deg. Furthermore, the effectiveness of the proposed elimination method is proven by a performance test.
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