Negative Refraction Of Surface Plasmon Wave In Metal/Dielectric Structures

The negative refractive index materials are characterized by simultaneous negative permittivity and permeability,so the refractive index of this kind of materials is negative.When electromagnetic waves propagate in the materials, the electric field vector,magnetic field vector and wave vector will not follow the right-handed law,and they form a left-handed law,so this material is called "left-handed materials"(LHM).In this material the wave vector k (phase velocity)and Poynting vector Sare anti-parallel,so there are novel electromagnetic properties,for example,the negative Snell's law,negative Doppler effect,negative Cerenkov radiation,etc.In 2001,Smith,proposed that the new meta-materials consisting of periodic structures can simultaneous have negative permittivity and permeability in the microwave frequencies,so the feasibility of manufacturing this meta-materials is proved.So far,study of negative refraction mainly realized in microwave band,and if use SPPs(Surface Plasmon Polarizations),this phenomenon will realize in optic frequency band.SPPs are waves that propagate along the surface of a conductor, usually a metal.These are essentially light waves that are trapped on the surface because of their interaction with the free electrons of the conductor.In this interaction, the free electrons respond collectively by oscillating in resonance with the light wave. The resonant interaction between the surface charge oscillation and the electromagnetic field of the light constitutes the SPPs and gives rise to its unique properties.Using SPPs we can control the propagation of light and limit that to a small extent,even less than the wavelength.If we could find waveguides that can serve as negative index material,then negative refraction can be realized in optic frequency band.And that can be used for controlling light propagation in nanometer scale,light guiding component in integrated circuit,making high- resolution lens, plasmonic chips,and so on.In the present thesis,I mainly studied negative refraction in different structures of SPPs waveguides and analyzed propagation of electromagnetic waves in the waveguide.Finally the permittivity and the permeability are calculated by simulation.The background of the thesis is introduced in Chapter 1.In Chapter 2 the conception of negative refraction and how to produce it are introduced.Chapter 3 is mainly about the fundamental theory of the SPPs and we simulated the propagation of SPPs.Also numerical calculation method FDTD method and dispersion models for metal are presented.We analyzed negative refraction existing in SPPs waveguides, and introduced the structures that can generate negative refraction by SPPs.After simulating different structures by the method of FDTD,we find the waveguide model that can generate negative refraction,and observed image by slab lens.