generation of plasmonic vortex with linearly polarized light

A nanoslit-arrayed plasmonic lens that can generate plasmonic vortex with linearly polarized light is theoretically and numerically studied. the topological charge (tc) of generated plasmonic vortex is the sum of the geometrical charge of the proposed plasmonic lens and additional angular momentum of ±1. the plasmonic vortex is determined by the pitch of the plasmonic lens, the nanoslit rotation directions, as well as the polarization direction of the incident light. combination of the geometry parameters of the plasmonic lens and the polarization direction of linearly polarized incident light, plasmonic vortexes with arbitrary tc are flexibly generated. moreover, by cutting the continuous nanoslit arrays into segments, highly ordered plasmonic vortexes are realized with small plasmonic lens size. comparisons with two slit plasmonic lenses are also presented to demonstrate the unique properties of the proposed plasmonic lens in plasmonic vortex generation.