The Study Of All Fiber Optic Current Transducer

This article studied the structure of All-Fiber Optic Current Transformer, compared and analyzed the advantages and disadvantages of several kinds of common Optical Current Transformer, non-interference structure, Sagnac-type structure and commonly used reflective structure. Through the establishment theoretical model of reflective structure, studied the affect of Linear Birefringence for all-optical current transformer in detail. And analyzed and compared some methods to reduce the effect of Linear Birefringence, include introducing a large number of circular birefringence、making very low linear birefringence optical fiber、specially processing sensing optical fiber loop and separating the Faraday effect and the linear birefringence and soon on. The results show that these methods can not fundamentally eliminate the effects of Linear Birefringence, but introduce some new problems. An improved in-line All Fiber Optic Current Transducer was proposed in this paper. By appropriately setting the Fiber Polarization Rotator(FPR), bending-induced linear birefringence of the forward light and backward light will cancel with each other. Theoretic and polarization analyzing、Simulation show that new scheme has a large improvement on such LB reduction. The measurement error of AFOCT will be reduced to 10-3.In addition, sensitivity and stability of the system has also been improved by the new structure. The locate deviation of FPR has affected the inhibitory of Linear Birefringence was analyzed by simulation.At the same time, this article also studied quarter wave plate temperature characteristics、production methods and Jones matrix, prepared lights phase modulators and other hardware devices. Described the closed-loop signal detection scheme and determined the method of approaching output optical signal.New method of eliminating the linear birefringence affect in new in-line All Fiber Optic Current Transducer has a certain significance of research.