Switching the Topological Charge of Surface Plasmon Vortex by Tailoring Polarization States

We demonstrate dynamically switching the topological charge of surface plasmon (SP) vortex in gold metasurfaces by altering the polarization states of incident light. Two SP vortex sources with different helicity are created by the optimized L-shaped and `+'-shaped nanoslits with right-handed circular polarized and linear polarized excitations, respectively. By elaborately arraying the nanoslits to form a circle, the topological charge of the created SP vortex can be switched from -1 to 1 via altering the polarization states of incident light from circular to linear. Moreover, based on such a strategy, the topological charge can be switched from 0 to 2 by elaborately arraying the nanoslits to form an Archimedes spiral. These results provide the extra degree of freedom to modulate the topological charge of SP vortex, promising practical applications in optical communication, particle trapping, and integrated photonic circuits.