Research On The Optical Characteristics Of The Ring Metal Micro-nano Sensor Based On SPPs

With the rapid development of micro-nano-technology and integrated optics,Surface Plasmon Polartons(SPPs)has attracted wide attention.When the light interacts with the metallic medium,the electron cloud can support a wave of charge density fluctuation on the surface of the metal,called a surface plasmon wave.In recent years,the properties of SPPs in metallic nanostructure have been studied both experimentally and theoretically.Simulations can save plenty of time,and can study the principle theoretically.Three different subwavelength metallic structures have been designed in this dissertation,and the optical properties and working principle of the structures have been studied by simulations.We report the optical properties of two-dimensional flat-bottomed periodic annular cavity arrays in hexagonal close-packing on a silica substrate are theoretically characterized by finite difference time domain(FDTD)simulation method.According to the simulated reflectance spectra,electric field distribution and charge distribution,we confirm that the localized surface plasmon resonances(LSPR)can be excited in cavities and gaps by linearly polarized light,resulting in reflectance dips.The wavelengths of these reflectance dips are effectively tailored by changing the geometrical pattern of cavity and dielectric materials filled in the cavities.Adjusting geometry size parameters of the flat-bottomed annular cavity,we observed that the proposed structure can be tuned over the broad spectral range of 400-2000 nm.The structure is not sensitive to the polarization orientation because of the circular symmetry and periodic hexagonal close-packing.The tunability of the resonant wavelength of the structure is of instructive significance for the design and optimization of the local surface plasmon resonance sensor,and can be applied to the refractive index sensor.We report the design of a simulation,and characterization of the special periodic ring cavity arrays.The special periodic ring cavity arrays have simpler structure design and much better sensing performance than the optical properties of two-dimensional flat-bottomed periodic annular cavity arrays.According to the simulated reflectance spectra,electric field distribution and charge distribution,we confirm that the surface plasmon resonances(SPPs)can be excited in cavities by linearly polarized light,which result in reflectance dips.We observed that the proposed structure can be tuned over the broad spectral range of 500-3000 nm by adjusting geometry size parameters of the special periodic ring cavity arrays.The structure is not sensitive to the polarization orientation because of the circular symmetry and periodic hexagonal close-packing.The sensitivity may up to 1865 nm/RIU when the structure is applied to the refractive index sensor.We report the design,simulation,and characterization of a plasmonic interferometeric sensor consisting of concentric semicircular grooves and circular slit patterned on a gold film based on the structure of a semicircular aperture-slit nanostructure patterned on a metal film.This structure is proposed to form two-arm,four-beam,planar plasmonic interferometers.Laying in-between the semicircular grooves&aperture and the linear groove-slit-groove interferometers,the circular slit&semicircular grooves interferometer shows higher light transmission and enhanced sensitivity.Compared to a linear groove-slit-groove plasmonic interferometer,the circular slit&semicircular grooves plasmonic interferometer can achieve 10-fold higher sensitivity.The simulated results show that this simple,efficient,and controllable scheme possesses unique features of high contrast,narrow linewidth,and large amplitude,which is promising for the development of multispectral and extremely compact bio-chemical sensors.