title: Focusing dynamics on circular distributed tapered metallic waveguides by means of plasmonic vortex lenses.
abstract: We investigate the focusing effect on circularly distributed planar tapered plasmonic waveguides by means of three-dimensional (3D) finite elements simulations. The proposed configuration allows nanofocusing on four faced planar nanotips, showing efficient condensation of surface plasmons polaritons (SPPs) at the silver/air interface toward the endpoint of the tips. By means of a plasmonic vortex lens it is possible to illuminate the tips with SPP waves carrying orbital angular momentum (OAM), namely plasmonic vortices. Our 3D simulations show that by acting on the topological charge of the plasmonic vortex the electric field charge distribution at the tips apex can be controlled accordingly to the input electric field phase distribution. The results for three particular OAM values are shown, along with a generalization for arbitrary plasmonic vortex angular momentum values.
authors.affiliation: Department of Physics and Astronomy, Padova University, Padova, Italy. tommaso.ongarello@venetonanotech.it
authors.forename: Tommaso
authors.initials: T
authors.lastname: Ongarello
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Parisi
authors.forename: Denis
authors.initials: D
authors.lastname: Garoli
authors.forename: Elettra
authors.initials: E
authors.lastname: Mari
authors.forename: Pierfrancesco
authors.initials: P
authors.lastname: Zilio
authors.forename: Filippo
authors.initials: F
authors.lastname: Romanato