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 x 10(-4) in Panda-Type PMF and 7.732 x 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.