Design of a dielectric chiral micro-structured fiber applied in a fiber optic current sensor

Abstract

During the process of drawing the screwed silicon-based fiber, there will be a uniform rotation rate in it, which results in a decrease of circular polarization degree of the fiber. In order to solve this problem, we presented a kind of dielectric chiral micro-structured fiber owing higher circular polarization degree. Meanwhile, the air holes of fiber will collapse during the progress of fiber drawing, which will change the position of air holes. As a result, the circular polarization degree of the fiber decreases. In order to reduce the change of circular polarization degree caused by the position fluctuation of the air holes, a highly symmetrical micro-structured dielectric chiral fiber was firstly designed in this paper. Then, we established a physical error model considering the fluctuation of the air holes’ position which was the design basis of the air holes’ position, size, and chiral parameters of the specific microstructure fiber. Next, comparing the circular polarization degree S3 of screwed silicon-based fiber and that of the dielectric chiral micro-structured fiber by simulation, it was proved that the dielectric chiral micro-structured fiber we designed has a higher circular polarization degree S3 than that of screwed silicon-based fiber. Finally, we applied the fiber designed in this paper as the fiber sensing coil in a fiber optic current sensor, and compared it with the fiber optic current sensor utilizing the original fiber sensing coil in ratio error. The simulation results proved that compared with the original system, dielectric chiral micro-structured fiber utilized as the fiber sensing coil in a fiber optic current sensor will decrease the ratio error by an order of magnitude in theory.