Surface Plasmon Polaritons Based Enhancement And Manipulation Of Electromagnetic Field

In recent years, as the development of nanotechnology and plasmonics, plenty ofnovel electromagnetic properties have emerged in the interaction between metallicstructures and light, such as surface electromagnetic confinement, near-fieldelectromagnetic enhancement and negative refraction. These properties enable manypromising applications in sub-wavelength focusing, high-resolution lithography,photovoltaic devices, and surface enhanced Raman spectroscopy. The contents of thework mainly include: Localized surface plasmon resonance based near-fieldelectromagnetic enhancement and surface plasmon waves based electromagneticmanipulation. The main contents of this work and novelties are listed as below:1. A new optical antenna structure is engineered and optimized. Fractal trianglesare introduced into the traditional diabolo nanoantenna to construct fractal diaboloantenna. The optical behaviors of these antennas are studied. It is found that both thefield enhancement and the resonant wavelength increases with the iteration of thefractal triangles. Detailed analysis of electric field, magnetic field and polarizationcurrent distribution reveals that fractal could increase the length of current paths,which will subsequently increase the effective length of the optical antennas. This partof the thesis explains how the fractal structures can improve the performance ofoptical antennas and provides theoretical reference for the following research.2. A new type of excitation source for optical antennas is engineered andoptimized. Inspired by Babinet’s principle, the radially polarized beam has beenintroduced into the excitation of split ring aperture. Due to the symmetric matchbetween the excitation and the structure, radially polarized beam could improve thefield enhancement two orders more than linearly polarized beam. This work revealsthat radially and azimuthally polarized beams are complementary to each other. Thesefindings extend the types for excitations of optical antennas, gives the guidance forengineering complementary optical antennas and provide theoretical reference foroptical antenna.3. A graphene based platform is constructed for manipulation of Airy plasmons.Based on Huygens-Fresnel principle for surface plasmons and vectorial surfaceplasmon propagator, propagation properties of graphene based Airy plasmons iscalculated. The propagation constant is found to be closely related to the surfaceconductivity. Thus, the propagation properties of graphene based Airy plasmons, such as propagation length and transverse deflection, can be controlled through tuning thebiased voltage. These demonstrations give another means for dynamically andreal-time tuning of Airy plasmons.4. The refractions of light on the boundary of metal/dielectric multilayermetamaterials are studied in detail. Based on the effective medium theory and Drudemodel, the exact expressions of two crucial frequencies, epsilon-near-zero andepsilon-near-pole frequencies are derived. The two crucial frequencies are “transitionfrequencies” where the permittivities of multilayers change signs. The opticalproperties of multilayer metamaterials will also be significantly changed based onwhich transition frequency is larger. This part of work study the influence of therelative position of epsilon-near-zero and epsilon-near-pole frequencies on thedispersion type of multilayers, divide the dispersion region for multilayers andprovide guidance for manipulation of light in multilayer metamaterials.