Generation and conversion of optical vortices in long-period twisted elliptical fibers.

We theoretically demonstrate that long-period twisted elliptical fibers have the ability to change in a certain wavelength range the topological charge of the incoming field by two units. We also show that such fibers can generate charge-2 optical vortices from the incoming Gaussian beams.

Optical vortices routing in coupled elliptical spun fibers.

We have studied the tunneling of a circularly polarized optical vortex (OV) in parallel strongly spun elliptical fibers. In this case it is possible to route the OV in a pure state from one of the fibers to another. We have determined the power efficiency of this process and have shown that such a directional coupler can serve for inversion of the topological charge of the incoming vortex.