Surface Isocratic Excitations Of Metal Nanostructures And Fano Resonance

The fast development of the surface plasmon theory open a new window for the research field of the thin-film solar cells, biochemical sensing, surface enhanced spectroscopy, optical waveguiding, and electromagnetic cloak. The great progress and the further development of the nanotechnology and the electromagnetic algorithm will allow the surface plasmon photonics theory find more applications. The thesis is divided into three parts. In the first part, the preparation, the light scattering properties, and the surface plasmon properties of the silver NPs are investigated. In the second part, the surface plasmon properties of a novel nanodisk structure with a built-in missing sectorial slice is investigated. In the third part, the effects of the spatial perturbation of minor nanoparticles on the surface plasmon properties of the nanostructure are investigated.Part one:The silver film is prepared by vacuum thermal evaporation technology and the silver nanoparticles are prepared by annealing the silver film. The effects of different annealing temperatures on the morphology of the silver nanoparticles are investigated. The electric field enhancement and surface charge distribution of the silver nanoparticles are simulated and calculated by the electromagnetic simulation method. The scanning electron microscopy (SEM), atomic force microscope (AFM), analysis software, and homemade light scattering device are used to study the morphology and light scattering properties of the silver nanoparticles. The FEM and FDTD are employed to calculate the electric field enhancements and the surface charge distribution.Part two:We proposed and designed a novel planar plasmonic nanostructure, a nanodisk with a built-in missing sectorial slice (NDBMS). This nanostructure is consisted of a nanodisk and a built-in missing sectorial slice. Angles of the slice vary from0to360°. By using the FEM and FDTD, the surface plasmon properties of a novel nanodisk with a missing built-in sectorial slice are investigated. The effects of the slice angle on the extinction spectra, electric field enhancements are investigated. The physical mechanism of the electric field enhancements and higher order Fano resonances are analysed. It has been found that the quadrupolar, octupolar, and hexadecapolar Fano resonances appear when the missing slice angle locates in a certain range. We have demonstrated that the higher order Fano resonances result from the coupling between the dipolar mode supported by the edge of the built-in missing slice and the multipolar ring modes. We also have found that the size of this structure only has a distinct effect on the spectral positions of the higher order Fano resonances while the ring width has a pronounced effect both on the spectral positions and the modulation depths of the higher order Fano resonances. The spectral line shapes of the higher order Fano resonances can be tuned flexibly by modifying geometrical parameters of this structure.