Plasmonic Zener tunneling in binary graphene sheet arrays.

We investigate the plasmonic Zener tunneling (ZT) in arrays of weakly coupled graphene sheet waveguides. By alternatively arranging the graphene waveguides with two different chemical potentials, the single surface plasmon polariton (SPP) band splits into two minibands, and tunneling between them occurs at the edge of the Brillouin zone. With a linear gradient of the propagation constant introduced by appropriately tuning the chemical potential distribution over the graphene sheet, the SPPs exhibit a sequence of Bloch oscillations and ZT transitions in the arrays. The simulated tunneling rate coincides with the theoretical analysis based on the coupled-mode theory, which can be tuned by varying the chemical potential difference between adjacent graphene.