Steering and multiplexing subwavelength plasmon beams*

Arc shaped nanoslits in thin silver films are used as sources and lenses for generating sub-wavelength plasmon spots with high optical near-fields. We introduce a continuous phase shift along the nanoslits to achieve steering of the plasmon focus spot. It is experimentally shown that such a phase control allows to move the plasmon focus by micrometers with a nanometer precision and to launch it on separate 250 nm wide silver nanowires placed in the focal plane. Our nanostructures demonstrating scanning and multiplexing functionality show a feasibility of the nanoscale manipulation with optical fields.