Analysis of mode characteristics and output efficiency of graphene equilateral triangle nanocavity with vertex output waveguide

In this paper, we propose and numerically investigate an integrated plasmonic device composed of a graphene monolayer equilateral triangle nanocavity and a cut corner of one vertex which is connected to an output waveguide. This integrated device with a certain chemical potential is surrounded by infinite area of graphene monolayer with another chemical potential. The quality factor (Q factor) and the output efficiency are systematically calculated as function of geometry parameters of the integrated structure and the material parameters of graphene. The simulation results demonstrate that there is a trade-off between the Q factor and the coupling efficiency of the proposed structure. In the integrated plasmonic device with R ₁ of 30 nm and an output width of 5 nm, a Q factor of 80.5 and the corresponding Purcell factor of 4.687 × 10⁷ are obtained when the chemical potential μ _c1 and μ _c2 is 0.9 and 0.59 eV respectively. Meanwhile, the output efficiency reaches 20.2 %. The proposed directional emission nanocavity with relatively high output efficiency and relatively high Q factor can be a fundamental structure of the filter or directional emitter in the future plasmonic integrated circuits or transformative plasmonics.