Abstract
Inspired by the recent development of graphene, we propose and experimentally demonstrate a novel metasurface, namely, spoof surface plasmonic graphene, for controlling the transports and emissions of electromagnetic waves. Similar to graphene, at the corners of the Brillouin zone for our designed metasurface, two bands of spoof surface plasmon polaritons (SSPPs) linearly touch together, forming Dirac-like cones. In the experiments, we directly observed the Dirac cones in the momentum space by using near-field scanning. When the frequency is changed from the lower cone to the Dirac point and to the upper cone, the corresponding SSPPs' transport on the metasurface shows negative group velocities, pseudodiffusion characteristics, and positive group velocities, respectively. The emission of the SSPPs to the air shows a transition of the wavefront from a concave to flat and finally to convex. The metasurface proposed here may find many potential applications in directional antennas, waveguide, diffusion-like transport, focusing and imaging devices, and integrated spoof plasmonic circuits.