Electron-injection Stimulated Graphene Surface Plasmon Wave To Generate The Transition Radiation

Deep influence has been generated in fields such as astronomy,radar,communication(broadband communication),electromagnetic weapons,electronic countermeasures,medical imaging(mark-less genetic testing,cellular level imaging),safety inspection(biochemical inspection)and non-destructive testing by the terahertz wave with some unique properties.The generation of terahertz radiation is based on optical,electronics,or nonlinear beat frequencies,but each has its own advantages and disadvantages,also has its own difficulties.However,the problems of terahertz sources is tried to solve by combining the comprehensive methods of electronics and photonics,which is used to generate the terahertz radiation from graphene surface plasma wave and transition radiation excited by electron beam in this paper.Although the current output power of the method is not high yet,its structure is simple and easy to implement,and the conductivity of the graphene in the material used can be adjusted by changing the bias voltage and doping,and the dielectric constant of the medium used in the structure can also be changed or adjusted as needed,thereby providing a potential highly available solution for developing terahertz sources that are practical and can be easily regulated.Graphene can not only excite surface plasmon waves in the terahertz waveband by excitation sources such as electromagnetic waves,photons,electron beams,etc.,but also exhibits electromagnetic properties like those of noble metals(gold,silver)in the terahertz band and infrared band.It also supports the transmission of surface plasma waves.Surface plasmon waves are slow waves formed by free electrons and photon interactions(collective oscillations)near the interface region of a metal or a material with metal-like conductivity characteristics.According to the above facts and based on the characteristics of electron beam,graphene,surface plasmon wave and transition radiation,a model established for electron transfer excitation of graphene surface plasmon waves to generate the transition radiation.Then rhe model is analyzed,and reasonably simplified and approximated according to the basic physical principles,the requirements of the topic and the applicable scope of the physical law to obtain a simplified incentive model.Based on the simplified model,the various components of the model were dismantled: electron beam,graphene,dielectric layers and their interfaces.Then the physical analysis of these parts is carried out separately: the electron field expression of electron injection is obtained with Maxwell's equations;the graphene displacement current expression is introduced with graphene characteristics;the boundary conditions are introduced according to the medium interface,and the various components are connected in series,finally expressions of the radiative power flow density expressions and radiation field is obtained.Then draw the field distribution map corresponding to the special discrete value of each variable in the expression by programming with the MATLAB numerical calculation tool,and give the comparative analysis and appropriate physical explanation,and draw the field amplitude at the same time relationshiping with each variable(continuous value).