Electrically controlled topological surface plasmon polaritons: integrating plasmonic metagates with graphene (Conference Presentation)

Topological photonics offers remarkable solutions to robust light propagation and coupling. Two challenges can be identified: (1) making topological structures reconfigurable, and (2) shrinking them to nanoscale. I will discuss a platform that addresses both challenges: a valley plasmonic crystal for graphene surface plasmons. We demonstrate that a designer metagate, placed within a few nanometers of graphene, can be used to impose a periodic Fermi energy landscape on graphene. For specific metagate geometries and bias voltages, the combined metagategraphene structure is shown to produce complete propagation band gaps for the plasmons, and to impart them with nontrivial valley-linked topological properties. Sharply curved domain walls between differently patterned metagates are shown to guide highly localized plasmons without any reflections owing to suppressed intervalley scattering.