  Experimental results from the generation of Raman sidebands using optical
vortices are presented. By generating two sets of sidebands originating from
different locations in a Raman active crystal, one set containing optical
orbital angular momentum and the other serving as a reference, a Young's double
slit experiment was simultaneously realized for each sideband. The interference
between the two sets of sidebands was used to determine the helicity and
topological charge in each order. Topological charges in all orders were found
to be discrete and follow selection rules predicted by a cascaded Raman
process.
