Output coupling from a trapped Bose-Einstein condensate in a vortex state

We consider the properties of an atom laser produced by the output coupling of a trapped vortex state with a Raman scattering process. We find a linearized analytic solution from which a generalized resonance condition for Raman output coupling is developed. Using numerical simulations of a two-component Gross-Pitaevskii equation in two and three dimensions, the output beam from a trapped central vortex state is analyzed for cases of pulsed and continuous coupling where the vortex core is either transverse or parallel to the direction of propagation. We show how the parameters of the Raman light fields control the spatial phase of the output beam.