Study On The Propagation Properties Of 2D Monolayer Materials' Surface Plasmon

Since the discovery of graphene,this unique two-dimensional single-layer semiconductor material has received widespread attention for its excellent physical and chemical properties.The surface plasmon waves can be support on the graphene surface.Surface plasmon is a special electromagnetic wave that can propagate on metal surfaces.This special electromagnetic wave can break through the diffraction limit and be applied to nano-scale optoelectronic devices and all-optical integrated circuits.Because of its broad application prospects,graphene surface plasmons once became a hot research direction.The advent of graphene has also led to the exploration of other two-dimensional materials.Like graphene,black phosphorene(BP)is also a two-dimensional semiconductor material formed by a single layer of atoms.Compared to isotropic zero-bandgap semiconductor graphene,anisotropic BP has some unique advantages,such as direct band gap,high switching ratio,etc.Black phosphorene also has a Drude-type conductivity similar to graphene,but it exhibits anisotropic.Therefore,the research on the BP surface plasmons has also become one of research focuses.In this paper,both graphene-supported surface plasmon and BP-supported surface plasmon have been investigated.In the dielectric-graphene-dielectric layered structure,in the terahertz and sub-terahertz bands,the non-linear term of graphene conductance is dominated by the applied strong electric field.Therefore,graphene can support the surface plasmon of the transverse electric mode.We explored the dependence of this non-linear graphene transverse electric mode surface plasmon wave on the number of graphene layers,the applied electric field strength,and the broadening width.We design a dielectric-loaded black phosphorene plasmon waveguide structure and explore the propagation characteristics of the surface plasmon in this structure in the infrared spectral region.The effects of the BP anisotropic conductivity,the size of the ridges,the electron doping concentration,and the coupling with the ridges on the effective refractive index were explored.The dependence of waveguide mode order on ridge width under different BP locating orientations was calculated numerically.In addition,we studied the propagation and coupling phenomenon of the BP surface plasmon wave in a parallel flat structure composed of separated single-layer black phosphorus.The wavelength dependence of the two coupling modes has been studied.And the effect of BP orientation on the wave vectors of different coupling modes has also been analyzed.Based on this results,a branching structure with switching effect is set up.The coupling distance under different conditions is calculated numerically.The above research results can provide some theoretical basis for the application basing on the graphene and BP surface plasmon.