Plasmonic characteristics of suspended graphene-coated wedge porous silicon nanowires with Ag partition*

Abstract

We investigate a graphene-coated nanowire waveguide (GCNW) composed of two suspended wedge porous silicon nanowires and a thin Ag partition. The plasmonic characteristics of the proposed structure in terahertz (THz) frequency band are simulated by the finite element method (FEM). The parameters including the gap between the nanowires and Ag partition, the height of the nanowire, the thickness of the Ag partition, and the Fermi level of graphene, are optimized. The simulation results show that a normalized mode field area of ∼ 10−4 and a figure of merit of ∼ 100 can be achieved. Compared with the cylindrical GCNW and isolated GCNW, the proposed wedge GCNW has good electric field enhancement. A waveguide sensitivity of 32.28 is obtained, which indicates the prospects of application in refractive index (RI) sensing in THz frequency band. Due to the adjustable plasmonic characteristics by changing the Fermi level (E F), the proposed structure has promising applications in the electro-optic modulations, optical interconnects, and optical switches.