Plasmonic nanofocusing using a metal-coated axicon prism.

We propose an excitation method for the localization of photons at the apex of a metal coated axicon prism. The cone angle of the prism and the metallic film thickness are designed to match the excitation conditions for surface plasmons. The plasmons propagate along the sides of the prism and converge at its apex. The resulting nanofocusing was investigated by simulating the intensity distributions around the apex of the prism using a finite-difference time-domain algorithm. For incident radial polarization, a localized and field enhanced spot is generated by the constructive interference of surface plasmons.