Plasmonic enhancement of terahertz devices efficiency

This paper reviews the plasmonic effects in graphene THz photodetectors (PD) and light emitters (LE). It is demonstrated that the devices based on double graphene-layer (DGL) or multiple graphene-layer structures with the graphene layers separated by thin tunnel barrier layers have advantages over the single graphene-layer (SGL) devices. In DGLs, this advantage is due to the photon-assisted resonant tunneling when the band offset of the graphene layers is aligned to the THz photon energy. The resonant emission or absorption of the THz radiation is enhanced by the cooperative resonant excitation of the graphene plasmons leading to an extremely high gain and/or responsivity in the graphene THz device structures.