| Surface Plasmons(SPs)are the coherent delocalized electron oscillations that exist at the interface between metal and dielectric medium.Due to the evanescent nature of SPs,light field with localized enhancement is confined at a scale beyond the diffraction limit.These make SPs widely use in perfect absorbers,nanolithography,surper resolution and plasmonic nanolens.In this thesis,we focus on the plasmon hybridization,surface plasmons based-perfect absorber,and surface plasmons nanolithography.The main contents and results of the thesis are listed as bellow:(1)Theoretical Study Electromagnetic Induced Absorption Effect of Surface Plasmon Based on Drude Model for Metal Nanostructures.In the research field of surface plasmons based-perfect absorber,a two-dimensional pyramid metamaterial absorber has been proposed.Starting from the wave equation,combining the dispersion relation and spatial distribution characteristics of the surface excitation,the basic properties of the surface plasmon polaritons at the metal/insulator interface are discussed,and the quantitative calculation of the field confinement degree is discussed in detail.The optical properties of the localized and conductive surface plasmon supported by the graphene system were explored,and the superiority of the graphene surface plasmon polaritons was demonstrated.Graphene has good electro-optic modulation characteristics;doped graphene can support plasmon mode in a wide range;graphene has ultra-high electron mobility,resulting in excellent electrical and optical properties.Therefore,based on these outstanding advantages,the introduction of graphene not only enriches the design method of plasmonic devices but also expands the application fields of plasmons.(2)Theoretical Design Surface Plasmon Metal Nanostructures Metamaterial Perfect Absorber.This work has given an overview of the palsmonic analog of electromagnetically induced absorption in a nanophotonic system.Then,we have theoretically and numerically investigated the palsmonic EIA effect and demonstrated a narrow-band perfect absorption in a two layer stacked matematerial.One attractive feature of this system is that the absorption peak has a linewidth than 10 nm and the absorptivity exceeding 98%.Another specialty is that the vertical distance is in the intermediate regime and the coupling exhibits the characteristics of both,the near-and far-field regime.Furthermore,the EIA-like system exhibts strong electromagnetic field enhancement at optical frequency,that is in favor of improving the sensitivity of spectroscopic devices.In the future,the plasmonic EIA absorber will find applications in optical filters,SERS,biosensors,nonlinear optics,and the related equipments.(3)Theoretical Design Mid-infrared adjustable near-perfect absorbers based on graphene metamaterials.We proposed and simulated the three-dimensional non-uniform vertical field in the medium(graphene)with the method of FDTD.It has given an overview of the plasmonic analog of the classical mode coupling induced absorption and the metamaterial absorption in a nanophotonic system.Then,we have numerically investigated the plasmonic absorption effect and demonstrated a narrow-band perfect absorption in a two graphene layer stacked metamaterial.One attractive feature of this system is that the absorption peak has a narrow linewidth of 160 nm and the absorbance approaching to 97.12%.Significantly,the absorption spectrum can be dynamically tuned by a small change in the chemical potential,in addition to varying geometrical parameters.Another specialty is that the vertical distance is in the intermediate regime and the coupling exhibits the characteristics of both,the near-and far-field regime.Furthermore,the proposed system exhibits strong electromagnetic field enhancement at mid-IR wavelength region,that is in favor of improving the sensitivity of spectroscopic devices.In the future,the graphene based plasmonic absorber will find applications in optical filters,SERS,bi osensors,nonlinear optics,and the related devices. |
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