Properties Of Localized Surface Plasmon Resonance And Surface Plasmon Polaritons Propagating In Metal Micro-And Nanostructures

Surface plasmon (SP) is an electromagnetic mode that formed by the interference between metal surface electron and incident light. SP is strongly dependent on the shape, size, material and surrond environment of noble metal nanostructure. Accoding to the size of nanostructure, surface plasmon is deviding to localized surface plasmon (LSP) and surface palsmon polaritons (SPPs). In this thesis, the resonance properties of LSP in silver nanostructure is investigated by discrete dipole approximation (DDA) method and the propagation properties of SPPs in waveguide is by fitine difference time diomain (FDTD) method. In this thesis, the research works mainly focused on the resonance properties of LSP and the propagation properties of SPPs as follow:1. Resonance properties of LSP in nanostructure(1) Two nanostructures are designed based on cascade enhanced electric field, and their optical peoperties are investigated by DDA method:the chain of three silver nanorods and the windmill-shaped nanostructures. For the former, the results show that compared with individual small nanorod and the chain of two nanorods, much enhanced electric fields are focused around the small nanorod of the chain of three nanorods due to the electric fields couplings between adjacent nanorods. For the latter, the results show that the cascade electric field enhancements occur at the lateral surface of the nanorods. Although the E field distributions vary with the incident polarizations, much enhanced electric fields always occur between the lateral surface of one nanorod and the tip of its perpendicular nanorod.(2) Two sysmetry breaking nanostructures are designed and invertigated by DDA method: the equilateral triangle with triangle notch and the asymmetry cylindrical nanorod dimmer. For the former, the results show that a Fano resonance line-shaped emerge in the extinction spectra, which result from the interference between the bonding and antibonding hybridized plasmon resonance. For the latter, the results show that two peaks are observed obviously in the extinction spectra of the asymmetry cylindrical nanorod dimer:the higher-energy anti-bonding mode and the low-energy bonding mode. The interaction of two hybridization plasmonic resonance modes resulting in an asymmetry line shape in the extinction spectra, which is considered to a Fano resonance profile Meanwhile, the LSPR properties of the asymmetry cylindrical nanorod dimer are analyzed by the coupling LC resonator model, and the resonance peak positions calculated by the LC resonance model are in good agreement with by DDA calculated results.2. Propagation properties of SPPs in MIM waveguide(1) The filter function of MIM waveguide with the gear-shaped nanocavity is investigated by FDTD. Since the gear-shaped gratings break the symmetric distribution of the resonance modes of the disk-shaped nanocavity, Fano resonance occurs in the gear-shaped nanocavity. The Fano resonance depends strongly on the structural parameters of the gear-shaped nanocavity. Compared to the MIM waveguide with disk-shaped nanocavity, the MIM waveguide with gear-shaped nanocavity allows for a much more sensitive detection of small refractive index changes of the filled media in the nanocavity.(2) The propagation properties of the metal-insulator-metal (MIM) waveguide with a nanoparticle in the insulator at the communication wavelength of 1.55μm are investigated by FDTD method. By study the effect of size, the position and the shape of metal nanoparticle on propagation properties, we found that the attenuation in the MIM waveguide is enhanced since the SPPs excites the LSPR of the metal nanoparticle.(3) Two type SPPs filter are designed and investigated by the FDTD method:Arc-shaped resonator MIM waveguide filter and one-end-sealed MIM waveguide filter. For the former, the results show that the transmission peaks in the transmission spectra are resulted by the resonance of the SPPs in the arc-shaped resonator. Meanwhile, structure can also act as a splitter and achieve the dual function of filter and splitter for subwavelength waveguide. For the latter, the results show that this structure shows a filter-like behavior, and the pass bands and stop bands in the transmission spectra are resulted from the constructive interference and destructive interference of the electromagnetic fields between the SPPs reflected at the sealed end and those of the SPPs propagating towards the open end.(4) An unidirectional SPPs generator with greatly enhanced generation efficiency is designed and investigated by FDTD method. The results show that the SPPs generation efficiency of the asymmetric single nanoslit with PVA film can be greatly enhanced compared with regular case due the transmitting antenna effect of sliver rectangle block. In addition, the corresponding wavelength with the maximum enhancement factor can be tuned flexibly by change the length and the position of silver rectangle block, the depth of nanogroove, and the thickness of PVA film.