Theory, Numerical Simulation, and Experiment for Directional Beaming by Surface Plasmon Diffraction
| Autor: | Liang-Bin Yu, 余良彬 |
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| Rok vydání: | 2003 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 92 The development of nanotechnology, coupled with economic consideration, started a trend of miniaturization of devices and systems for higher performance and lower cost. However, several severe difficulties cast a shadow in the road of miniaturizing optical elements, devices, and systems. In order to expedite the paradigm shift, people are looking forward the ways to surmount those obvious barriers in advance. In 2002, an astounded phenomenon called “directional beaming” was announced. It means that if a single slit is patterned with additional surface corrugations beside, the emerging field from the slit will not suffer from the diffraction and concentrate in specific direction instead. This phenomenon soon motivated numerous potential applications in the microscopic world; nevertheless, the underlying mechanism was still unknown and was not identified in published literature. The aim of this thesis is to investigate the physical origin of directional beaming. After reviewing the previous literatures about the research of surface plasmons and diffraction gratings, we eventually recognized that the diffraction of surface plasmons propagating on the grating structure beside the slit is of the essence of the surprising behavior. Since the activities of the surface plasmons are actually modulated by the grating simultaneously, we introduced RCWA formulation to pursue its precise dispersion relation. By comparing resultant theoretical data to associated FDTD simulations and experimental results, we found the consequence did greatly substantiate the validity of the surface plasmon diffraction scheme. After elucidating the fundamentals of directional beaming, we also examined in detail several supplementary issues, such as the influences of grating geometry to the beaming situation, etc., to provide a comprehensive groundwork for future investigations and applications. Through extensive numerical examinations, we achieved an interesting conclusion that for a large groove depth, scatterings of surface plasmons by surface grating were more significant, thus the number of grooves needed for beaming is reduced. This turns into a useful criterion in practical application of this beaming phenomenon. Furthermore, pragmatic optical head designs for optical lithography, storage, and microscopy, along with new approaches to the unsolved issues in the topic of extraordinary transmission, were examined in detail in this dissertation to complement the research of directional beaming even further. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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