Generation of radially and azimuthally polarized beams with elliptical anisotropic twisted optical fibres

We have established the expressions for the higher-order modes with the azimuthal number l = 1 and the corresponding propagation constants of anisotropic twisted fibres near the resonance points. It is shown that the modes are presented by a superposition of circularly polarized optical vortices with unity topological charge with radially or azimuthally polarized optical modes. We have predicted that the anisotropic twisted fibres can be used as an efficient and stable all-fibre generator of radially and azimuthally polarized vector beams