Researches On Transmission Properties Of Surface Plasmon Waveguide And Optical Enhancement In Periodic Nanostructures

Surface Plasmon Polaritons(SPPs)are a kind of charge density wave propagating along the metal surface due to the interaction of free electrons and photons at the interface of the metal and the medium,which breaks through the advantages of the diffraction limit and is the miniaturization of the photonic device.In this paper,a finite element method(FEM)and coupling mode theory(CMT)are used to study the transmission characteristics of the surface plasmon waveguide and the enhanced transmission characteristics of the sub-wavelength hole array structure light,and the theoretical analysis and the numerical simulation method are combined.Some special optical properties of metal-dielectric-metal(MIM)waveguides are studied and analyzed,and a variety of functional photonic devices with the application prospect are designed.The main work are as follows:1.The structure of metal-dielectric-metal waveguide coupling resonator is designed.The refractive index sensing characteristics of the structure are studied by FEM method,and the Fano resonant effect is analyzed.In addition,after optimizing the parameters,the maximum refractive index sensitivity of the structure reaches 1160 nm/RIU,and the corresponding sensing resolution is 8.62×10~?55 RIU.The results are useful for the application of high sensitivity nanoscale refractive index sensors and biosensors.2.The structure of two MIM waveguides coupled with nanoscale ring cavities is proposed.The sensing characteristics of MIM structures are systematically analyzed by studying the transmission spectra.There are three resonance peaks in the transmission spectrum,that is,there are three resonance modes,in which the transmission peak is linearly related to the refractive index of the material.The theoretical value of refractive index sensitivity(S)up to 1500 nm/RIU is obtained by optimizing the structure parameters.At the same time,the filter characteristics of the complex MIM waveguide structure are analyzed.The optimized structure can work in the filter of the telecommunication wavelength.3.Two kinds of wedge-shaped metal slit array structures and triangular hole array structures are designed.Results show that,multilayer wedge metal slit structure can realize multiple transmission peaks and infrared band enhanced transmission and wide-frequency transmission,and the wedge-shaped structure embedded in rectangular cavity can realize local field enhancement and optical angle transmission at the exit of slit.The research results have some guiding significance for the design of optical signal transmission,broadband transmission and near-field optical acquisition device.