  Here we employ both dynamic and geometric phase control of light to produce
radially modulated vector-vortex modes, the natural modes of optical fibers. We
then measure these modes using a vector modal decomposition set-up as well as a
tomography measurement, the latter providing a degree of the non-separability
of the vector states, akin to an entanglement measure for quantum states. We
demonstrate the versatility of the approach by creating the natural modes of a
step-index fiber, which are known to exhibit strong mode coupling, and measure
the modal cross-talk and non-separability decay during propagation. Our
approach will be useful in mode division multiplexing schemes for transport of
classical and quantum states.
