Study On The Propagation Properties In Rectangular Cavity Plasmon Waveguide

Surface plasmon polaritons are electromagnetic waves confined near the metal/dielectric interface,which can propagate in metal constructions with sub-wavelength size exceeding the light diffraction limit.Optoelectronic components designed based on surface plasmon polaritons have smaller sizes than photonic components,which can improve the integration of optoelectronic devices.In this thesis,rectangular cavity plasmon waveguides are proposed according to the eigenmodes’ characteristics in the double-interface planar plasmon polaritons waveguide.Through analyzing the electromagnetic fields of the electromagnetic wave propagating in the waveguide,numerically,by finite element method,the propagation characteristics of the electromagnetic wave are studied in the cavity.1.The eigenmodes in a metal/dielectric/metal symmetric planar waveguides are analyzed.The type and number of guided modes in the planar waveguide and the relationship between the mode’s propagation constant and the thickness of the dielectric film are studied.Based on this,the number of guide modes in the rectangular cavity waveguides,and the constants dependent on the parameters of the cavity are analyzed.Then,the range of the structural parameters are determined for remote transmission according to the research results.It is shown that the fundamental mode is more suitable for remote transmission,because its imaginary part of the constant is smaller than others.2.Rectangular cavity waveguides with a square hole in the center of the "—" "L" and“十”structures are proposed.Through diffracting by the square hole,the electromagnetic wave can be excited when the light illuminate vertically.The influences of the structural parameters of the waveguide on the transmission characteristics of the guide modes are discussed.By changing the properties of the incident light,such as the polarization direction and polarization states,the relationship between the excitation of the surface plasmon polaritons and the polarization of the incident light,and the resonance characteristics of the waveguide for different wavelengths are studied.The results show that by changing the polarization of the incident light,it can be realized that the surface plasmon polaritons be splitted in the waveguide and the splitting ratio can be controlled.The circular or elliptical polarized light can also be splitted into two mutually perpendicular linearly polarized beams.The resonance effects of the waveguide make the selectivity for the excitation light,the resonance wavelength can be modulated to the visible region or the red/near-infrared region.The research results of this thesis have certain guiding significance on the beam splitting propagation in certain directions and polarization controls for surface plasmons,and filtering functions,and so on.