OPTICAL VORTICES IN WEAKLY ELLIPTICAL ANISOTROPIC FIBRES WITH TORSIONAL MECHANICAL STRESS
In the present paper we have obtained the modes and the corresponding propagation constants of weakly elliptical anisotropic optical fibres with torsional mechanical stress. Far from the resonance values of the pitch twist, the modes are found to coincide with the modes of ideal fibres with stress with high accuracy. Moreover, the circularly polarized optical vortices with topological charges ±1 are demonstrated to be robust in such a fibre. The analysis of the mode propagation constants shows that the mutual influence of stress-induced circular birefringence and the spin-orbit interaction provides the effective reduction of linear anisotropy-induced mode dispersion.