Birefringence in photonic crystal fibers - a numerical approach based on the plane-wave method

We apply the fully vectorial plane wave method to calculate birefringence in photonic crystal fibers with circular and elliptical holes. Holey fibers provide the possibility of reaching extremely high modal birefringence retaining single mode guidance at the same time. Such Hi-Bi holey fibers are naturally of particular interest for sensing applications. From the technological side it is important to know which types of fiber profiles lead to the high values of modal birefringence, and the present contribution includes a comparison of selected fiber microstructures with elliptical air holes from the point of view of attainable birefringence.