Research On Electromagnetic Characteristics And Terahertz Radiation Of Micro-nano Structure

With the development of THz science and technology.Many unique advantages of THz have been gradually discovered.The THz source is currently an urgent problem in order to promote the development and application of THz.Nowadays,the processing technology of micro-nano photon structure has made great progress.The radiation generated by the electron-excited micro-nano photon structure can cover the whole terahertz band.Therefore,it is currently a very promising direction to find a THz radiation source by combining the electronic and photonics.In this paper,Smith-Purcell(SP)radiation is generated by uniformly moving free electrons to excite the micro-nano structure.The physical mechanism for generating high power and efficiency terahertz radiation is studied systematically.The terahertz radiation of micro-nano structure is mainly explored from the following aspects:1.Starting from the reflective grating excited by the uniformly moving electrons,the radiation field and the dispersion equation are analysed according to the Maxwell's equations and the boundary conditions.The efficiency and frequency of SP radiation are mainly determined by the energy of the electron beam and the grating period.At the same time,the radiation field of transmitted micro-nano grating structure are analyzed.The radiation efficiency,duty cycle and depth of the two structures were compared.2.When the electrons with uniform motion skim over the metal micro-nano structure,the effect of the boundary can be equated to an equal positive charge formed by the electrons on the symmetric surface of the grating.Therefore,the electron and mirror charge can be regarded as an oscillating dipole,whose oscillation frequency is mainly determined by the electron rate and grating period,and the theoretical method of oscillating dipole generation radiation can be used to analyze the electron excited micro-nano structure to generate terahertz radiation.3.In this paper,a new structure is proposed to stimulate SP radiation,and the electron beam channel is formed by opening holes in the wall of the metal lattice array.The SP radiation is enhanced when the electrons through the metal hole array structure due to more dipole oscillation happening,and the adjustment effect of the hole structure on SP radiation is analyzed.4.At present,two types of analysis models are mainly used to study the SPradiation in high beam energy case,namely the evanescent wave theory and the surface current model.In this paper,the author found out that these two kinds of analysis are feasible partially.For analyzing radiation energy generated by ultra-high energy electron beams moving above the micro-nano structures,we used the theory of evanescent wave to analyze SP radiation frequency peaks,and the surface current model is effective in the radiation power.Finally,this theory is used to analyze the SP radiation characteristics at 1 GeV electron energy for application.5.Photonic crystals are a class of micro-nano structures with bandgap effect,and Electromagnetic wave whose energy falls in the "band gap" region cannot propagate.This paper studies the dispersion curve of metal photonic crystals,obtains the band diagram of metal photonic crystals through theoretical analysis,and discusses the effects of relevant parameters of photonic crystals on the photonic band gap.Finally,the SP radiation characteristics of metal photonic crystals relationship with the band gap are analyzed.