Generic optical vortex in a strongly elliptic optical fibre

We investigate the propagation of optical vortices in strongly elliptic weakly guiding fibres. A novel method of the perturbation theory developing is suggested based on the simple change of variables that effectively makes it possible to take account of the field amplitude corrections in higher orders of perturbation theory. The form of a generic elliptic vortex in elliptic fibres is found to be a mixture of partial circular vortices.