Dynamic switching of the chiral beam on the spiral plasmonic bull's eye structure [invited]

A polarization-dependent switchable plasmonic beaming structure composed of metallic hole surrounded by double spiral dielectric gratings is proposed. The main mechanism of the proposed structure is based on the angular momentum change of surface plasmon caused by the spiral geometry. On-and off-states of the proposed device are determined by the condition whether the rotating direction of incident polarization is the same as or opposite of the direction of the spiral rotations. Qualitative analytical expressions of the switching mechanisms and full-vectorial numerical results are presented.