Abstract
This dissertation contains the studies of metallic nanostructure-excited surface plasmon polaritions (SPPs), surface plasmon resonances (SPR), and their applications for the waveguides and bio-sensors. Chapters were assorted according to the excitation configurations: nanohole near-field excitation and periodic nanostructure coupling. In the first chapter, I introduced the basic optical properties of surface plasmon and methods for SPPs/SPR excitation. After that, form the viewpoint of application, I conferred on the suitable configuration to exciting and measuring SPs in waveguides and bio-sensors. In the studies of waveguides, I used a combination of wavelength-tunable near-field excitation system and leakage radiation microscopy to study the mode properties in plasmonic waveguides. In the Chapter 3, wavelength dependent propagation length, multimode interference, and coupling length in a dual waveguide in a dielectric-loaded SPP waveguide (DLSPPW) were presented. This configuration shows its advantage in real-time plasmonic waveguide characterization with tunable wavelength and excitation positions, and low background noise. Based on these, in Chapter 4, I introduced the two-layer DLSPPW (TDLSPPW). This waveguide consisted of two dielectric layers (high-index/low-index) on a silver film. Experimental and simulated results showed it can reduces the transmission loss of propagating SPPs. The propagation length of SPPs in a TDLSPPW provides about 1.6 times longer than in DLSPPW. In the developing of biosensor, the periodic metallic nanostructures were employed into SPR coupling. Based on the highly sensitive to the environmental refractive index (RI), the SPR was applied in antibodies detections. I used thenanoimprint process to fabricating nanostructure onto plastic substrates. This process has reduced the cost and time of procedure. In the optical properties, the presented structure provides many modes of SPR. By energy coupling between modes, a non-symmetry peak in the transmission spectrum was founded. This excitation configuration showed the advantage in resonance wavelength- and modes-tunable. It enhanced the RI sensitivity. In Chapter 5, I demonstrated that how to calculated the effective refractive index and thickness of biomolecular layer by Fano resonance modes using wave equation method in dual-period gold nanogrid arrays. A modified dispersion relation was suggested to getting an accurate propagation constant. By applying it into wave equation, thickness determined by wave equation method is more accurate than by bulk sensitivity method. In Chapter 6, I firstly introduced the concept of digital detection into SPR-based bio-sensor. By a checkerboard design, experimental and simulated results showed that polarization dependent SPR can be excited in a local area. These areas were employed into sensing elements. After the optimization, I used a hunger of 12.5 um × 12.5um sensing elements to detecting antibodies. The experiment showed that limit of the digital detection is about 1000 times lower than traditional analog detection and the dynamic range is about 100 times higher than conventional SPR detection. The proposed method is very useful for detecting ultralow concentration of analytes with non-uniform distribution on the sensor surface.