Researches On Manipulation Of Surface Plasmon And Optical Propteries In Periodic Metallic Nanostructures

Surface plasmon polaritons (SPPs) or called Surface plasmon (SPs) are a state of evanescent wave, which are localized on the surface of a metal by the interaction of free-electrons and photons. All kinds of photonic nano-devices based on SPs are considered to be the basic of all-optical integrated loop with nanometer scale. Sub-wavelength metal nanostructures are the main structures to excite and control SPs. The metal nanostructures photon apparatus which can excite effectively SPs not only improve the properties of traditional apparatus but also produce some newfangled physical phenomena and achieve new functions.In this work, using the Finite-Difference Time Domain method (FDTD), we study the optical properties of metallic periodic nanostructures. The basic physical properties of surface plasmon resonance are analyzed by constructing different structure parameters. The results enrich the adjustment measurements of the transmission progress of the metal structure in subwavelength dimension. Corresponding physical mechanisms are analyzed, and potential optical applications are explored. The main research works are listed as following:1. The optical and SPs properties of the subwavelength double-layer periodic gold nano-slit with slanted sidewalls arrays are studied. We compare the optical properties of similarities and differences in two cases of the coaxial and non-coaxial double-layer slit (i.e., the slits have lateral displacement) and analyze the two different resonance modes (SPs resonance and localized waveguide resonance) of the subwavelength double-layer slit with slanted sidewalls arrays. The influences of structure parameters such as lateral displacement, distance between layers, slit width and film thickness of the structure on the optical properties and SPs resonances are analyzed in detail. Many interesting physical phenomena are discovered, such as the blue-shift, red-shift, splitting, degeneration, enhancement, broadening, narrowing of the resonance peaks, and so on. The simulation results presented here may prove a useful guide to design metallic slit optical devices.2. The optical and SPs properties of the sub-wavelength double-layer periodic gold rectangle-slit arrays/film and slanted-slit arrays/film are discussed. Compare to the monolayer sub-wavelength periodic gold rectangle-slit, the rectangle-slit arrays/film system appear more transmission peaks. Moreover, the transmissions between the resonant peaks are very small and there exist a band gap. This proves that the composite system has better filter and frequency choice properties than that of the single perforated film. We compare the optical properties of the monolayer slanted-slit arrays and slanted-slit arrays/film system and analyze the modulation effect of different structure parameters on the composite system. The result indicates that the composite system has more SPs modes and more modulation parameters than the single structure.3. The optical and SPs properties of gold nano-particle arrays are analyzed. We calculate theoretically on the different nanoshell thicknesses, the nanoshell sizes and distances between the nanoshells in the nanoshell arrays and present the field distributions of different resonance peaks. We propose that the peaks of the lower energy mainly origin from the sphere plasmons coupling and the peaks of the higher energy are mainly attributed to the coupling between the sphere plasmons and the cavity plasmons. The emergence of the wide forbidden band gap and the enhancement of electric fields in the system are intriguing in designing devices such as band-pass metal filter and biosensors and so on. The optical properties of gold nanotube array with a non-coaxial core can be tuned by the core offset, intertube spacing, the size and the thickness of the nanotube with a non-coaxial core in the metallic array structure. The SPs resonance multipolar characterizes are discussed based on the field distribution. The results presented here may find applications in scanning near-field optical microscopy as tips.4. The gold nanoshell contain medium and gold nanotube contain defect structure are studied. The increase of core dielectric constant ε1and the dielectric embedding medium dielectric constant ε2can lead the transmission spectra red-shift. The tunability of the wide forbidden band gap in the system is intriguing in designing devices such as band-pass metal filter and biosensors. The optical properties of gold nanotube arrays can be tuned by the different defects such as remove a specific nanotube, fill medium with different dielectric constants in the middle nanotube and change the size of middle nanotube. Metal nanoparticles behave more adjustable characters by introducing different medium and defects. The results have guiding role to broaden the sub-wavelength periodic metal structure in optical device applications.