| Summary: | 博士 === 國立臺灣大學 === 工程科學及海洋工程學研究所 === 104 === Since the surface plasmon was discovered in 1958, the upward trend in this field does not stop until today. This dissertation demonstrates several plasmonic components from absorbers to radiators. The noble metal gold is selected to be the metallic material in the following designs, therefore, an analytic model of dielectric function for gold is introduced to derive the dispersion relations of some fundamental geometries, such as multilayer structures or core shell nanoparticles. A special mechanism of absorption induced by the core shell nanospheres was found. Because the particle size is larger than the sub wavelength of incident light, the mechanism of absorption can be treated as the result of multi-modes combination and the associated circulation of energy flow is found inside the core shell nanospheres. Two periodic structures were studied for surface enhanced Raman scattering by controlling the geometries to enhance the electric field.. One is the quasi-3D plasmonic crystal and the other is the inverted pyramidal structures with tips. As the development of surface enhanced Raman scattering becomes flourish, the directivity of scattering light is getting attention. Thus, in the final part, the structure of concentric rings for a dipole radiator is proposed. The function of the multi-ring not only enhances the electric intensity of near field but also improves the directivity of scattering light, which is taken from the radiation pattern of far field. Furthermore, the experimental result proves the proposed concept.
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