Terahertz plasmonic rectification in a spatially periodic graphene

The plasmonic terahertz detection in a dual grating-gate graphene structure with an asymmetric unit cell is studied theoretically using a hydrodynamic approach. Two plasmonic effects of rectification of terahertz radiation—the differential plasmonic drag of charge carriers and the plasmonic electron-hole ratchet—are introduced and investigated. The plasmonic electron-hole ratchet effect appears only if the carriers of opposite signs are there in graphene under different subgratings of the dual grating gate. We demonstrate that the electron-hole ratchet effect dominates in the terahertz frequency range.