| Surface Plasmons (SPs) which are coherent oscillations of conduction electrons on a metal surface excited by electromagnetic radiation at a metal-dielectric interface have variety of applications in chemistry, optical devices, spectroscopy and bio/chemi sensors. Plasmon scattering is a growing area of importance for nonconventional meta-materials, condensed matter physics, and surface chemistry, thus it is very interested to study. A simulation tool for imaging scattering properties allows ab-initio design for plasmon devices as well as gives better physical insight for experiments. Furthermore, due to the high electric field density associated with SPs, Second-Harmonic Generation (SHG) is expected to be enhanced thus gives us extra physical insights.In this thesis, a simulation tool is developed to calculate the scattering properties of Surface Plasmon Polaritons (SHG) at both fundamental frequency (FF) and second-harmonic (SH). We present a comprehensive study of linear and nonlinear effects observed in the scattering process of surface plasmon polaritons (SPP) from localized surface deformations at a metal/dielectric interface. The electromagnetic field at the fundamental frequency (FF) is first determined by solving the corresponding set of reduced Rayleigh equations. The complete solution of these equations then allows us to investigate both the complex structure of the scattered electromagnetic field as well as the subtle mechanisms by which incident SPPs are scattered into radiative modes (light) and outgoing SPP waves. Furthermore, the electromagnetic field at the FF is used to determine the nonlinear surface polarization at the second harmonic (SH) and subsequently both the electromagnetic field distribution as well as the amount of light generated at the SH. In this thesis, we will discuss our results including the size dependence of the scattering into both surface and radiated waves for several defect shapes as well as the computational issues and the physical phenomena of the scattering process.This thesis is organized as follows. In chapter 1, I will give a brief introduction of SPs as well as their various applications. In chapter 2, the background theories as well as numerical techniques are discussed. Chapter 3 gives us a detailed description of surface SHG from scattering of SPPs by 1D Gaussian metallic nanostructures. Consequently, in chapter 4, the theory is extended to 2D circularly symmetric metallic nanostructures, which include Gaussian, Sphere-cap and Cylinder. Finally in Chapter 5, the some future direction of this thesis work is described. |
