Single-mode optical fibers with geometrical birefringence: analysis of the propagation by means of finite element method

This work presents the results of an analysis regarding propagation in single-mode fibers conducted by means of finite element method. A particular form of the functional is taken, in order to avoid the presence of nonphysical spurious solutions. Special attention is then given to the choice of the mesh when profile geometry is not circularly symmetric, like in the case of fibers able to preserve the state of polarization or nominally single-polarization. This situation has been carefully analysed, showing that particular new kinds of index profiles, such as elliptical azimuthally modulated W profiles, are able to produce extended intervals of single-polarization operation, to the point where their practical use appears feasible.