Design of high birefringence stress-induced polarization-maintaining fiber based on utilizing geometrical birefringence

Considering the utilizing of geometrical birefringence, we propose a new type of stress-induced polarization-maintaining fiber (PMF) with a ‘leaf-shaped’ core —a structure found by combining the merits of elliptical and rhombic core shapes. The finite element method (FEM) is used to compare and analyze the contribution of the elliptical, rhombic, ‘star-line shaped’ and ‘leaf-shaped’ core on geometrical birefringence. The results show that this kind of PMF improves the polarization-maintaining performance of the fiber significantly, and its birefringence value can reach 7.692×10-4 in Panda-Type PMF and 7.732×10-4 in Bow-Tie PMF which are doubled compare with the traditional Panda-Type PMF. Analysis of the mode field performance also indicates that the designed fiber is suitable for the sensing field. At the same time, this fine-diameter PMF conforms to the trend of miniaturization of current used fiber-optic sensors and can be applied to fiber optic gyroscopes.