Properties And Applications Of Surface Plasmon Polaritions In Sub Wavelength Metal Micro/nano-waveguide Structures

Using surface plasmons (SPs), the light can be manipulated in subwavelength scale, which opens up possible applications in nanoscale optical circuits. As the fundamental element of integrated photonics,micro/nano optical waveguides have attracted widely attention in recent years. Plasmonic waveguide offers the enhancement of the local electromagnetic field and the propagating of light beyond light diffraction limit. In this thesis we research on the transmission and enhancements of SPs in micro/nano structures based on optical waveguides and their potential applicants, which include the polarization characteristic of SPs in the chemically synthesized sliver nanowires waveguide and the resonant enhancement of SPs in the nano slot waveguide.Chemically synthesized crystalline metallic nanowires (NWs) can support propagating SPs with lower losses than lithographically defined waveguides and can be easily manipulated to construct complex optical devices, which make them ideal candidates to transmit the optical signal at nanoscale. In the first part of the thesis, we research the polarized excitation and radiation characteristic of SPs in the single Ag nanowire. On this basis, we design the subwavelength polarization controller, which can realize the control of intensity and polarization. Based on this structure, we propose a novel V-shaped polarization beam splitter which shows a new way to manipulate the polarization and intensity at the nanoscale. In addition, we study the influence of near-field coupling on the radiation intensity and find completely different polarization properties from that in the single nanowire. In this thesis, the research on the polarization control of SPP in silver nanowires has profound significance and broad application prospects for the photonic integration technology.Metal slot waveguide, as a typical metal-dielectric-metal waveguide,can obtain super light local field in the nanoscale, and have low transmission loss in the visible region. It can be used as an effective field enhancement structure. In the fourth part of the thesis, we introduce the dispersion theory of coupled mode and obtain the solving model of effective wavelength for the rectangular slot antenna. Then using the approximate solving methods, we get the simple analytical expression of the effective wavelength which can be used as design rule of the aperture antenna from visible to THz. In the fifth part of the thesis, we study the plasmonic resonances of double nanoholes in metal films. In addition to the usual gap-mode Fabry-Perot resonances, an additional wedge resonance is observed, which is sensitive to the curvature of the cusps in the double nanoholes. Experimental transmission spectra agree well with finite-difference time-domain simulations showing these separate resonances. The study about the resonant enhancement of slot waveguide is very important for the practicality of the optical antenna and micro-nano sensors.