▎ 摘　　要

We theoretically study a graphene-based plasmonic waveguide composed of graphene, hexagonal boron nitride and active layer heterostructure, which can gate the transmission of a surface plasmon polariton (SPP) localized near the interface between the active layer and graphene. When a gate voltage is applied above a certain critical value, the charge-density modulation in the quasi-2D electron gas formed in the inversion layer can induce a local plasmon resonance. Since the local plasmon resonance is strongly coupled to the SPP, it can suppress the transmission of the SPP. The main advantage of our device lies in the sharpness of the switching line shape, since the operation manifests the underlying resonance phenomenon. By taking the active layer to be the p-type Si(100) layer, we calculate the propagation length of the SPP with varying gate voltage. We show that the wavelength of the SPP is reduced to approximately 1/100 of that of an incident light and the propagation length of the SPP is significantly reduced by a factor of approximately 20 upon switching. This ensures that our plasmonic waveguide can operate effectively as a plasmonic switch for the SPP.