Gradient Conductivity Graphene Surface Plasmon Polaritons Terahertz Waveguide

The terahertz(THZ)wave is a waveband between microwaves and light waves.It is an electromagnetic wave whose frequency is from 100 GHz to 10 THz,and its wavelength is from 30 ?m to 3 mm.Its short wave band and infrared light coincide.The long wave band coincides with the millimeter wave and submillimeter wave,so the terahertz wave is in a very special area in the spectrum.The terahertz wave in this area has many unique properties,so now it is the hotspot of scientific research.The terahertz waveguide has Unique attributes have important applications in all aspects of life.Different waveguide structures have different advantages and disadvantages,so when choosing a waveguide structure,it will be selected according to actual needs.Surface Plasmon Polaritons(SPPs)can break the diffraction limit and are the core technology for device miniaturization.Graphene is a two-dimensional material with good conductivity and high electron mobility.Graphene surface plasmon polaritons can overcome the shortcomings of the traditional metal surface plasmon polaritons.The surface plasmon polarons supported by graphene have strong locality.,Low loss and other excellent performance,the most important feature is that it can be controlled by external electric field or doping.At present,the graphene SPPs waveguides are mostly concentrated in the planar structure,while the graphene cylindrical structures are less studied,but the cylindrical structures have many unique properties,such as angular symmetry.In this paper,the surface plasmon waveguide of cylindrical graphene is studied first,and then introduced from a cylindrical single-layer graphene waveguide,and a cylindrical bilayer graphene waveguide is gradually proposed.Due to the coupling between the two layers of graphene,the waveguide breaks the limitation that both the transmission length and the locality cannot be emphasized,and can realize the high localization and low loss of the SPP transmission at the same time,and the structure is simple and can be practically manufactured..The focus of current research is on graphene hard-border waveguides.However,graphene hard-border waveguides are too ideal and do not take into account the effects of boundary mutations.In practical applications,the abrupt change of the boundary does not cause a sudden change in conductivity.Therefore,the characterization method of conductivity based on graphene surface plasmon waveguide with a gradual structure was studied,and a graphene conductivity characterization method suitable for any graded structure was proposed.This method is closer to the actual situation and can ignore the substrate.The shape does not need to consider the influence of the boundary mutation,and this method is used to study the graphene waveguides with different structures,which lays a foundation for the further study of the application of graphene waveguides.