Birefringent optical fiber with dispersive orientation of polarization axes.

We demonstrate for the first time in optical fibers the "dispersion of the axes" phenomenon, which relies upon spectral dependence of polarization planes of the guided modes. This feature was achieved in a specially designed side-hole fiber by combining linear birefringence induced by a pair of holes located in the cladding and the elliptical core tilted with respect to the symmetry plane of the holes. We performed numerical simulations of this design properties. The side-hole fiber with a tilted core was fabricated and experimentally studied. The orientation of the principal polarization planes of the fundamental modes varied by 14.5° in the analyzed spectral range. This value is in a good agreement with the simulation results.