Production of biaxial polarization-maintaining optical fiber with panda-type and elliptical-core geometry

Polarization Maintaining (PM) fibers can be produced in different ways in terms of their stress-birefringent geometric structures such as Panda-type, bow-tie and elliptical core [1] . These designs in principal function in the same way causing internal stress on the core and creating birefringence between two orthogonal (slow and fast) axes. In the typical Panda-type PM fibers, polarization extinction ratio (PER) is preserved over 30 dB along the slow axis and there is over ~ 10 dB difference between the fast and slow axes (Region 1 and Region 2, respectively, Fig. 1.b .). On the other hand, elliptical core PM fibers can be produced without boron-doped stress rods and thus they are easier to manufacture than the other two PM fibers with compatible birefringence values. Some of the applications require utilizing PM fiber components in order to developed environmentally-stable laser systems [2] , [3] . For these reasons, a specialty PM fiber structure may be needed in which the properties of both Panda-type and elliptical core geometry PM fibers can be used together.