The generation of optical vortices and shape preserving vortex arrays in hollow multimode waveguides

It is predicted that by coherently combining appropriate sets of E H-mn modes of hollow square cross section multimode step-index waveguides, individual optical vortices and shape preserving vortex arrays can be generated. The vortices formed in this manner have intensity and phase characteristics similar to those found in Laguerre-Gaussian beams. The resulting vortex fields should be useful for holding, manipulating and imparting orbital angular momentum to atoms and microscopic particles inside hollow waveguides. The advantage of realizing vortex fields in hollow waveguides is that the interaction lengths can be made much greater than in free-space. It is also possible to envisage hollow waveguide optical circuits formed on the surface of suitable substrates. These circuits can be used to realize multiple vortex beam configurations in which atoms can be held and manipulated.