Robust higher-order optical vortices for information transmission in twisted anisotropic optical fibers

Abstract

Abstract We study the propagation of light in twisted anisotropic fibers by obtaining the analytical expressions and propagation constants for higher-order modes with the azimuthal number | ℓ | > 1 . It is shown that for arbitrary fiber parameters, the modes are elliptically polarized optical vortices of well-defined orbital angular momentum. We reveal the phenomena of orbital birefringence and the optical Zeeman effect for the higher-order topologically charged fiber modes. Finally, circularly and linearly polarized optical vortices are demonstrated to be modes that are robust against small constant and spatially varying perturbations of both fiber material and form anisotropy; this robustness is due to the effects of the spin–orbit interaction and/or torsional-stress-induced orbital birefringence.