The Design Of Novel Plasmonic Waveguides, Lasers And The Study Of Optical Properties Of Double-Triangle Nanoparticle Arrays

More and more metallic nanostructures have been fabricated out due to the increasing advances in micro-fabrication techniques. Those metallic nanostructures possess unique functional properties, which have presented great potential for application in the research fields of surface enhanced Raman scattering (SERS), integrated circuits (IC), biosensors, data storage and optical antennas. Meanwhile, It has merged into a new rapidly growing discipline, called surface plasmonics, which covers the research area of physics, chemistry, material science, information science, biology, and their inter-disciplines.In this thesis, we will give detailed studies on the physical properties and operation quality of novel plasmonic waveguides and plasmonic nanolasers using numerical calculation methods. In addition, as an important auxiliary tool for analyzing experimental results, we will use numerical calculation to intensively study the magnetic resonances of our experimental fabricated artificial "magnetic atom" structure-gold double-triangle nanoparticle array. The thesis is mainly composed of four sections that are arranged as following:1. We will give a detailed introduction about the physical conception, characteristics, and basic features about surface plasmon polaritons. Additionally, we will also overview the research development, current status and application potential of three important surface plasmonic research areas for:plasmonic integrated circuits, nanolasers based on plasmonic resonators, artificial "magnetic atom"2. We propose a novel plasmonic waveguide structure-trapezoid-shaped groove plasmonic waveguide. Based on mode analysis using finite element method, we present a detailed study of propagation dispersion relation, propagation length, mode field distribution of our proposed waveguide structure. Comparing to the currently well known V-groove plasmonic waveguide structure, it is shown that the trapezoid-shaped groove could confine the propagation mode field tightly to the nano-gap region between the bottom wedge tips, and operate in a much broader bandwidth. In addition, we also study the effect of the groove depth, wedge angle, and wedge roundness on the propagation characteristics. We find that this trapezoid-shaped groove waveguide structure possesses very good operation stability. Feasibility of using such trapezoid-shaped groove waveguide for the design of efficient subwavelength plasmonic elements is also discussed on the nanoscale whispering gallery resonators as an example.3. We propose a novel plasmonic nanolaser structure. This nanolaser is constructed by a dielectric gain core coated by a nano-scale silver shell layer. According to our numerical calculations, we find that this metallic nanoshell structure could sustain highly localized plasmonic resonant modes, called void modes. When a void mode is excited, majority electric fields will be well confined within the shell cavity. Therefore, void modes usually possess highly quality factors and relatively small mode volumes. We select void modes as stimulated emission modes, and investigate their lasing condition. The calculation results demonstrate that it requires much lower gain threshold to fulfill stimulated emission in silver nanoshell than other known plasmonic lasing resonators. Additionally, we also investigate the effect of symmetry breaking of spherical shell cavity on the lasing threshold. We expect that our proposed metallic nanoshell structure could be exploited as a promising path towards an effective subwavelength coherent light source that could operate as room temperature.4. Using angle-resolved nanosphere lithography, we can fabricate out metallic double-triangle nanoparticle array with their openings oppositely arranged. The fabricated double-triangle nanoparticle can be seemed as a split-ring resonator (SRR), which is a kind of artificial "magnetic atom". We experimentally and numerically investigate the optical properties of this double-triangle nanoparticle array under normal and oblique incidence conditions. We find that, under normal incidence, the electric field component of incident electromagnetic wave can excite anti-symmetric magnetic resonance in double-triangle nanoparticles. At anti-symmetric magnetic resonance, the induced magnetic dipoles in a unit cell oscillate out of phase, and the overall magnetic response of the array will be totally cancelled out. Under oblique incidence, when the electric field component is parallel to the double-triangle arms, a symmetric magnetic resonance will be excited. While the electric field component is along the double-triangle bases, both symmetric and anti-symmetric magnetic resonances will be excited simultaneously. In addition, we also investigate the dependent relationship of magnetic resonant positions on the fabrication conditions.