Research On Optical Phenomena Of Micro And Nano Metallic Composite Structures And Their Applications

The research work within this dissertation is supported by a grant from the Major State Basic Research Development Program of China (No.2006CB302905) and grants from the National Natural Science Foundation of China(No. 10474093,90206002). In this dissertation, field enhancement effect of localized surface plasmons(LSPs) has been applied into polymer optics to optimize the optical performance of polymer materials. Optical properties of random metallic nano-particles doped polymer films and ordered metallic structures have been investigated by using optical experimental method and numerical simulation method. Their potential applications in optical waveguide, switch, data storage, sensor and polarization optical elements are also investigated.The main research works and conclusions are as following:1. Dots beyond optical diffraction limit were successfully recorded on the azo-polymer films by using Scanning Near-field Optical Microscopy(SNOM). Influence of illumination time on the shape of recorded dots were analyzed; Forming mechanism of these dots were analyzed based on gradient force theory. The diameter of the smallest dot is 120nm under 457nm laser irradiation. A new pure optical writing/reading method was also proposed for near-field optical storage.2. Influence of Ag nano-particles on the optical properties of azo-polymer films was investigated. Transmittance enhancement phenomena of Ag nano-particles aggregates was observed by using SNOM and the phenomena were analyzed due to the excitation of LSPs of these Ag nano-particles aggregates. Far field optical experiments results shown that the isomeration speed of azobenzene polymer molecules can be enhanced with Ag nano-particles at certain concentration, and the speed would be decreased with higher Ag nano-particles concentration. These results are useful for developing new kind high speed optical recording and switch materials.3. Optical properties of Ag nano-particles and Rhodamine B doped PMMA polymer films were investigated. The refractive index and films thickness were measured by usingθ—2θprism coupler instruments and experimental results shown that this kind polymer films can be used as optimized polymer planar waveguide. The fluorescence spectrum of the dye doped polymer waveguide with different Ag nano- particles concentration shown that the fluorescence of RB would be enhanced with Ag nano-particles at certain concentration. The largest fluorescence enhancement factor is 3.8 in our experiments. Our experiments have potential applications in developing new kind polymer waveguide amplifier or laser.4. Polarization properties of sub-wavelength metallic gratings(SWGs) in visible light band were investigated by using Rigorous Coupled Wave Analysis(RCWA) method. Influence of structural parameters on the polarization beam splitter ability of three kind SWGs (Au, Al, Al/Au) were analyzed. For the new kind Al/Au double layer SWGs, transmittance and reflectance for different polarization and wavelength can be tuned by changing the height ratio of Al and Au. Our work is usefully for developing new kind Sub-wavelength Optical Elements(SOEs). A new kind H-shape grating SPR biosensor was proposed and influence of structural parameters on the performance were numerical simulated.5. Optical properties of micro and nano metallic structures were described and experimental investigated. The applications of through-pores metallic arrays with different period on Surface Enhanced Raman Scattering(SERS) were primarily investigated.Highlights of the dissertation are as following:1. LSPR effect was introduced into polymer optics to optimize the optical performance of polymer materials. Influence of Ag nano-particles on azobenzene molecules' isomeration speed was investigated for the first time. Transmittance enhancement of Ag nano-particles aggregates on the azo-polymer films was also observed for the first time. The influence of Ag nano-particles on the fluorescence intensity of RB doped polymer planar waveguide was investigated for the first time. This kind metallic nano-particles doped polymer materials have potential applications in polymer optical elements.2. Polarization properties of Al, Au, Al/Au SWGs in visible light band were investigated by using RCWA method for the first time. Simulation results provide references for developing new kind SOEs.