Research On Transmission Properties Of Surface Plasmon Polaritons Based On Comb-shaped Graphene

The fast development of optical communications has led to an increasing demand for various types of optical filters.The surface plasmon polariton wave is a special kind of electromagnetic wave that can propagate on the surface of metal and medium,using its highly localized characteristics,one can break through the diffraction limit,and build filter pieces that are much smaller than the wavelength size of the operating frequency band.The study of surface plasmon polariton on metal surfaces over the past decades has encountered difficulties with limited operating frequency bands and difficult postproduction adjustment.The discovery of graphene opens up new possibilities for the application of surface plasmon polariton,which support surface plasmon resonance in the terahertz to mid-infrared frequency range and have a much larger operating frequency bands than metal.This thesis focuses on the design of SPP filters based on graphene nanoribbons.The physical parameters modeling,dispersion characteristics,mode distribution laws,and regulation methods of SPP in graphene nanoribbons are used to design the filter structure on this basis.The simulation calculations and analysis verification of the designed structure are performed using the relevant numerical calculation algorithms.The work in this thesis provides a theoretical basis for the fabrication of ultra-micro surface plasmon polariton filters based on graphene nanoribbons,which are of reference value for achieving large-scale integrated optoelectronic devices.The work of this paper is mainly as follows:The research background is introduced,the discovery and properties of surface plasmons are briefly explained,the characteristics of graphene-based surface plasmons are compared with those of metal surfaces.The excitation,regulation and detection of graphene SPP are introduced.Then the main simulation method used in the paper: the Finite-Different Time-Domain(FDTD)principle is briefly described,and the stability conditions,boundary conditions and excitation source settings required for the calculation are introduced.The calculation method of transmission spectrum is explained.The principle and dispersion characteristics of the surface plasmon are briefly analyzed,and the numerical calculation model of graphene is explained.The transmission characteristics,mode distribution are given.According to the dispersion characteristics and mode distribution of graphene SPP,two bandpass filter structures based on graphene nanoribbons with a right-angle defect structure in the SPP propagation direction was designed.Using the FDTD numerical calculation,the transmission and transmission characteristics of each structure were studied,and the regulation of the structural performance by changing the structure size parameters and graphene chemical potential energy was explored and verified.A WDM structure based on comb-shaped graphene nanoribbons is designed.Based on the simple structure,by adjusting the length of the resonator,the width of the nanoribbons or the chemical potential of graphene,the wavelength and transmission characteristics of the wavelength division multiplexing can be adjusted in a relatively wide frequency range.In addition,using the Fabry-Perot(F-P)resonance theory and timing coupled mode theory,the mechanism of the proposed WDM structure is analyzed in detail.