Stress birefringence analysis of polarization maintaining optical fibers

Thermal stress characteristics for polarization-maintaining optical fibers (PMFs) with panda shape, bow-tie shape, elliptical shape, and “pseudo-rectangle” shape are analyzed by finite element method. Stress birefringence is calculated by principle of the stress-photoelastic coupling effect. Stress distribution contours and the stress birefringence distributions are presented. At the same time, the stress birefringence is studied in different stress regions with different structure parameters, and compared with that obtained from the classical thermal stress theory. The numerical results demonstrate that a higher degree of birefringence can be obtained by increasing area of stress applying region, decreasing the distance of the stress region from the core, as well as changing stress region shape, etc. The “pseudo-rectangle” shape fiber can produce a larger and more uniform stress birefringence than the panda fiber, the elliptical fiber and the bow-tie fiber. The elliptical core bow-tie fiber has also bigger stress birefringence, which is induced by the thermal stress and as well as geometrical shape.