Plasmonic axicon micro-lenses for chemical sensing

We report on the fabrication of plasmonic hybrid sensors made of a micro-axicon dielectric lens and a single metallic nanoparticle. The dielectric lens produces a Bessel-like beam of light at its apex under plane wave excitation confining light in a narrow and intense beam with a low divergence. This Bessel-like beam can be used to optimize efficiently the excitation of a plasmonic nano-object and the collection of its far-field collected signal. This hybrid structure using the optical properties of a single metallic nanoparticle can act as a highly sensitive nanosensor.