Research On The Properties And Applications Of Graphene Plasmons

Surface plasmons(SPs)is an electromagnetic oscillation formed by the interaction of free electrons and incident photons on the surface of metal.Surface plasmon has the characteristics of being able to break through the diffraction limit and local field enhancement,and can realize the regulation and manipulation of light at nanoscale,which provides great potential for the development of new nano-integrated photonic devices.In recent years,many photonic devices based on surface plasmons have been proposed and designed,which are widely used in perfect absorbers,broadband modulators,filters,chemical biosensing and other fields.However,there are some disadvantages of traditional metal surface plasmon,such as high ohmic losses and unable to be dynamically adjusted,which limits its application in the field of photon integration.Graphene Surface Plasmons(GSPs)has become a research hotspot in recent years due to its unique optical characteristics,electrical tunability,and strong locality of electromagnetic fields.This article mainly studies the basic principles,optical characteristics,and the method for realizing tunability of Graphene Surface Plasmons(GSPs),then two kinds of perfect absorbers based on different graphene structures are designed.The structure was simulated and analyzed by finite element method.The results indicate principle mechanism and the influence on the change of geometric parameters and Fermi energy levels on the structure.The main contents are as follows:1.A brief introduction to the principle of surface plasmon polaritons,excitation methods,and properties of local surface plasmon polaritons.2.Firstly,the electronic band structure and optical properties of graphene were introduced.Then,we studied the properties and adjusting methods of graphene surface plasmons,and the development of graphene surface plasmons were also introduced.At last,the numerical calculation method of this thesis is introduced.3.Based on graphene surface plasmons,a tunable dual-band metamaterial absorber based on cross-shaped graphene is designed.The absorption spectra of the structure,electric field profile,and the influence of the graphene Fermi energy levels on the absorption were analyzed in detail.The results show that there are two perfect absorption peaks(99.8% and99.3%)at 10.81 μm and 11.25 μm.4.Based on graphene surface plasmons,an independently tunable perfect absorber based on the plasmonic in double-layer graphene structure is designed.The geometric parameters of upper(lower)graphene layers and the influence of the graphene Fermi energy levels on the absorption spectrum were analyzed.In addition,the absorption of the structure at different incident angles in TE and TM modes has also been discussed.The results prove that proposed structure is a polarization and angle insensitive triple-band perfect absorber.