Research On The Electromagnetic Characteristic And Applications Of Surface Plasmon Based On Periodic Structure

Surface plasmonic(SP)has unique optical properties,it can break through the limit of traditional light size,which has a wide range of application in storaging,switching and filtering.With the development of the novel artifical electromagnetic materials,surface plasmon has been extended from optical frequency to the microwave and terahertz frequency.In this dissertation,SP based on periodic structure is analyzed in detail,and the electromagnetic properties and applications of the spoof localized surface plasmon(Spoof LSP)and the graphene plasmonic in the low frequency range are investigated.The main contents and contributions of the dissertation include the follows aspects:1.Based on the analysis of the electromagnetic characteristics of the spoof LSP,we demonstrate that periodically textured closed surface with multiple groove depths can support multi-band spoof LSP.It is interesting to note that the Spoof LSP in each band resemble those generated by the textured closed surface of the same periodicity with the corresponding single groove depth.The resonant zones of the two modes are independent of each other and can be flexibly controlled by changing the depth height and the refractive index.2.A resonant cavity on the surface of spoof LSP is proposed and the analytical model of the resonator is established by using the modal expansion technique(MET)and effective medium theory(EMT).The existence of multiband spoof LSP in closed textured cavities with multiple groove depths is proposed in this dissertation.It is interesting to note that the spoof LSP in each band resemble those generated by the textured 2D cavities of the same periodicity with the corresponding single groove depth.3.By analyzing the scattering characterisitcs and field distribution,we find the groove with depth gradient can achieve local field enahncement.A non-concentric structure which support spoof LSP is proposed,and the field enhancement factor of this structure is quite sensitive to the polarization angle of the incident wave,which can find potential applications in polarization sensor.4.A high-contrast gratings(HCGs)structure is proposed to support the spoof surface plasmon.Theoretical and experimental results have proved that the HCGs structure can support the spoof LSP.And a cavity using HCGs is proposed in the dissertation,which supports the spoof LSP resonance.5.By introducing a defect unit or multiple defect units,a method of realizing the adjustment of the specific frequency is proposed by using the theory of band gap and defect state of spoof SPP.The electromagnetic energy is limited to the defect by designing defects on the microstrip spoof SPP waveguide.The simple band-notched coplanar waveguide and microstrip are theoretically investigated and experimentally,and a narrow or broad stopband would be generated flexibly and conveniently.The theory and experimental results show that the two models can be used to design a bandgap filter and notch antenna,which can find potential applications in microwave and THz transmission.6.The control of electromagnetic wave based on graphene plasma structure is studied.A novel structure for tunbale terahertz absorbter based on graphene with dielectric slab struture is proposed.Both narrowband and broadband tunable absorbers are demonstrated with simple structure and apply bias voltages conveniently.A general circuit model is presented to study the absorption of electromagnetic waves by the uneven dielectric slab structure.Compared with the full-wave simulation results,the proposed method shows high efficiency and the results obtained from the suggested method agree well with those from the full-wave simulations for a normal and oblique incidence.It is very potential to design novel graphene plasmonic devices in the future.