表面電漿效應之於奈米天線之研究

本論文分為兩大主題: 主題一: 外廓型(contour)奈米天線之表面電漿研究: 主題一利用有限元素法探討奈米銀殼核領結型奈米電漿天線之近場光學性質與表面電漿子共振在傳統實心領結型天線與外廓式奈米領結型天線對入射平面波之交互作用。模擬結果顯示藉由使用外廓式奈米領結型天線以及改變大小、厚度與幾何等參數會有很強的峰值與波長紅移現象產生，且此現象是在相等幾何結構的實心奈米銀領結型電漿天線中所看不到的。主題二：外廓型奈米天線埋入不同深度矽基板之表面電漿研究: 主題二利用有限元素法設計一種中空式外廓式奈米領結型天線的結構型，我們考慮以外廓型奈米天線埋入不同深度(v=-70,-35,-25,-10,-5,0,5,10,20,30,35nm與單一在空氣(air)中)，如此不須更改天線尺寸大小，只需調整天線埋入矽基板深度，便可設計出很寬頻譜的奈米電漿天線。

關鍵字

有限元素法；近場光學性質；表面電漿共振；奈米電漿天線

並列摘要

This thesis is divided into two major themes: Topic 1: The study of outline type (contour) nano antenna surface plasmon: In Topic 1, we numerically analyze a broadband plasmonic outline bowtie antenna over a large parameter space by means of finite element method with three-dimensional calculation. The antenna is composed of a pair of triangular gold with outline shape placed in close proximity to each another. We show how the structural parameters affect the antenna resonance conditions, such as peak resonances wavelengths, electric field intensities, propagation properties, component field and total field distributions, charge densities and electrical filed stream lines at spectral points of interest. In addition, the characteristics of transmittance spectral of a periodic antenna array corresponding to the bonding mode and anti-bonding mode are investigated as well. Simulation results show that it is possible to tune an antenna with a constant length over a wide spectral range (ranging in 0.3-5.0μm or more range) while maintaining a constant antenna dimension, reduce the antenna footprint by a factor of 4.98, and increase the gap enhancement by 23%. Topic 2: The A-shape plasmonics nanoantenna with different depths embedded in silicon substrate. In Topic 2, The A-shape plasmonics nanoantenna with different depths (i.e., (v=-70,-35,-25,-10,-5,0,5,10,20,30,35 nm) embedded in silicon substrate is also discussed by using the finite element method. The influence of its structural parameters on the antenna resonance conditions have been examined at spectral points of interest. In addition, the characteristics of transmittance spectral of a periodic antenna array corresponding to bonding mode and anti-bonding mode are investigated as well. Through these simulations, we show that it is possible to tune an antenna with a constant length over a broadband spectral. These results demonstrate that these antennas offer more compact dimensions when compared to a bowtie antenna and that the operating wavelength of the antenna may be tuned over a wide range by changing the outline thickness, while maintaining a constant antenna footprint. Increasing the antenna length and decreasing the outline thickness both act to red-shift the antenna resonance conditions. Both the thickness of the vertical edge of the antenna and its position are found to be very important for optimizing the antenna performance. It is anticipated that these results will inspire further developments in plasmonic nanoantennas with complex geometries and will have future applications in near- to mid-infrared spectroscopy and sensing.