Investigation Of Surface Plasmonic Devices Based On Periodic Metallic Nanostructures

Surface Plasmon Polaritons (SPP), a surface wave, is an electromagnetic oscillation induced by the interaction of photons and free electrons at the metal/dielectric interface, whose features include near-field enhancement, subwavelength localization and focusing, super-resolution imaging, and so on. Because of these characteristics, SPP have extensive application prospects in many fields, such as high-sensitivity sensing, subwavelength optical waveguide, high resolution optical microscope, nanolithography, and metamaterial. As the development of micro/nanofabrication technologies and theoretical research, extraordinary optical performances and application potentials of SPP have become the most scientific significance and development value in the field of nanophotonics.Based on freestanding metallic grating and metal nanohole arrays, this thesis investigates the role of SPP in the extraordinary optical phenomenon of complex metal nanostructures. Applying the finite-difference time-domain method and finite element method, we conduct some investigations in three aspects, including extraordinary optical transmission in the metallic gratings, improving the performance of surface plasmon resonance sensor by applying nanostructure, and nanostructure sensor design based on metal nanohole arrays and annular aperture arrays. Major research works are as follows:Firstly, to explore the role of SPP in extraordinary optical transmission of metallic gratings, we design four kinds of micro/nano grating structures, and reveal their extraordinary optical phenomenon. Starting with freestanding metallic grating, we give an explanation to physical mechanism of transmission minimum and maximum in the structure. We design a metallic grating with nonlinear ellipse walls, and theoretically explain non-resonant broadband extraordinary optical transmission. This structure can be used to design polarizer with wide bandwidth and high extinction ratio in the visible range. Next, we present a metallic grating and waveguide structure, in which multiple transmission dips and peaks in the transmission spectrum are related to waveguide layer thickness. Physics of these resonant modes are further interpreted. Moreover, the simultaneous excitation of three types of resonant modes supported results in a narrow-band high absorption peak in the structure. Moreover, based on single layer metallic grating, we propose symmetry-reduced double layer metallic gratings structure and analyze the cause of two transmission dips. We find that the position and angular tolerance of two dips can be controlled by adjusting the thickness of metallic grating. This structure can be used to develop a dual-wavelength filter. The researches of extraordinary optical transmission of these metallic grating structures will contribute to the miniaturization and integration of optoelectronic devices.Secondly, to improve the performance of surface plasmon resonance sensor by applying nanostructures, we have designed two kinds of complex structures composed of nanostructure and metallic film to enhance the linearity and sensitivity of surface plasmon resonance sensor. One structure is an integration of nanograting structure and traditional SPR configuration, which can generate two obvious dips in the reflection spectrum. When the nanochannel among two structures is used as sensing area, both dips respond nonlinearly to the refractive index of the sensing area, which guarantee the designed structure with high refractive index sensitivity and good linear approximation. The other sensing structure is to embody metallic nanowires in a polymer positioned above traditional SPR configuration to enhance the structure sensing performance. Although the coupling of metallic nanowire and metal film has no influence on the increase of structure sensitivity, localized enhancement around metallic nanowire can generate strong localized electromagnetic field transfer to the interface of sample and structure, which improve the interaction of structure and surrounding medium and improve sensitivity. This work plays an important role for improving the performance of surface plasmon resonance sensor.Thirdly, based on metal nanohole arrays, we have designed three kinds of nanostructure sensors with high refractive index sensitivity and figure of merit by applying the coupling among different plasmon modes. Starting with nanohole arrays sensor, we find that the change of incident and azimuthal angle can induce the splitting of surface plasmon mode in theory and experiment. The increase of incident angle can decrease significantly penetration depth into dielectric layer, which can improve surface sensitivity of structure. We also present three types of annular aperture arrays by using the coupling among different plasmon modes in the nanostructures:symmetric annular aperture arrays with dielectric substrate, asymmetric annular aperture arrays with metal substrate, and binary annular aperture arrays with metal substrate. Using coupled-mode theory, we analyze the physical mechanism of resonant mode in three types of nanostructure. The resonant modes in three types of nanostructures have narrow bandwidth, which lead to high refractive index sensitivity and high figure of merit of the designed structure, particularly Fano resonant mode. This research is valuable for innovative nanostructure sensor development.At the end of this thesis, we summarize all the contents, and provide some prospections for future research in developing optoelectronic devices and nanostructure biosensor.