Spinning spoof surface plasmons and their topological responses.

Spoof surface plasmons (SSPs) mimic characteristics of optical surface plasmons in microwave and terahertz frequencies. Manipulating SSPs has attracted widespread attention for extending plasmon applications into the low-frequency range. In this Letter, we show that spinning SSPs can be excited on a twisted groove (TG) metallic cylinder by oblique incident waves. The incident angle of waves and the twist angle of the grooves play essential roles in manipulating the propagation orientation and the rotation direction of spinning SSPs (SSSPs). Finally, we discuss an application of the SSSPs in topological photonic systems. By periodically arranging the TG cylinders, we show that this spinning feature will lead to topologically non-trivial bands in such a photonic crystal, where the topologically protected edge modes arise near the boundary. [ABSTRACT FROM AUTHOR]