Surface plasmon polaritons generated by optical vortex beams

We demonstrate that surface plasmon polaritons can be generated by optical vortex beams at normal incidence focused on a metal surface. The surface plasmon resonant angle can be modulated by the radius of the optical vortex beam in the case of different metal/dielectric interface configurations. Our experiments show that the fluorescence in the vicinity of the metal film surface can effectively be excited and detected within the inner ring of the optical vortex beams due to the localized surface plasmon polaritons. (C) 2008 American Institute of Physics.