  Using an example of a Raman active medium we describe how a common nonlinear
process of four-wave mixing can be used to induce strong coupling between the
spatial and temporal degrees of freedom in optical waves. This coupling
produces several unexpected effects. Amongst those are cascaded excitation of
multiply charged optical vortices, spatial focusing in a nonlinearly defocusing
medium and generation of helically shaped spatio-temporal optical solitons.
