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Title: | 高深寬比U型共振腔振動模態與局部表面電漿子之互制行為探討 Interaction between the Vibration Modes and Localized Surface Plasmon Resonances of High Aspect Ratio U-shaped Cavities |
Authors: | Tung-Po Shen 沈東柏 |
Advisor: | 吳政忠(Tsung-Tsong Wu) |
Keyword: | 局部表面電漿共振,共振腔模態,雷利表面波,聲子晶體,共振器, Localized surface plasmon resonance,Cavity mode,Rayleigh surface wave,Phononic crystal,Resonator, |
Publication Year : | 2015 |
Degree: | 碩士 |
Abstract: | 局部表面電漿共振(LSPR)為電子在奈米金屬結構中的振盪現象。在感測方面,相較於表面電漿共振(SPR)感測器需要較大的傳播面積,LSPR感測器由於其侷限於奈米結構中的特性,不需要大面積即可有很高的靈敏度,可以縮小系統整體的體積。近年被提出的高深寬比U型共振腔可產生耦合LSPR及其共振腔模態,將入射光強烈侷限於結構中。應用於感測方面也有相當高的性能,且只需要少許U型共振腔即可激發,然而該模態只能以斜向入射的入射光所激發。本文將U型共振腔視為懸臂樑陣列,以數值模擬研究其振動模態與光在此共振腔中的互制行為。在U型共振腔振動的情況下,LSPR耦合共振腔模態可以垂直入射光激發,其對光的侷限性以及感測性能與共振腔振幅有關。感測性能在特定振幅下會較原先靜止且光以斜向入射的設計高。另外,若光以斜向入射振動中的U型共振腔,靈敏度在高階的共振腔振動模態會隨振幅上升。在驅動U型共振腔的部分,本文在ST-cut石英上設計指叉式電極產生雷利表面波,驅動U型共振腔產生振動,並加上聲子晶體形成表面波共振腔加強U型共振腔振幅。數值模擬結果指出加上聲子晶體共振腔後,U型共振腔的振動振幅提高約3倍。 Localized surface plasmon resonance (LSPR) is the oscillation of electron confined in the metallic nanostructure. In sensing application, high sensitivity can be realized in small surface due to the nature of LSPR. Contrast to the sensing system based on surface plasmon resonance (SPR) require large propagating surface, the system based on LSPR can be miniaturized. A high aspect ratio U-shaped cavities structure was proposed recently. The LSPR coupled to the cavity mode in the structure can strongly trap the light and have superior sensing performance. It can also work in a few cavities which meet the purpose of miniaturization in LSPR based system. However, this mode can only be excited by the oblique incident light. Consider the U-shaped cavities as an array of 2-D cantilever beams, the interaction between the vibrational mode of the cavities and the light becomes an interesting topic. In this thesis, the optical behaviors in the vibration modes of the U-shaped cavities are numerically investigated. The LSPR coupled to the cavity mode and its higher order mode can be excited by the normal incident light in the active U-shaped cavities. The light confinement and the sensing performance are related to the vibrational amplitude of the cavities. The sensing performance is higher than the original design in certain amplitude. In the active cavities with oblique incident light, the sensitivity is increased as the vibrational amplitude increase in higher order vibrational modes. In practice, the cavities are designed to be driven by the Rayleigh surface wave which is generated by the pairs of the interdigital transducers. A 2-D phononic crystal is also adopted. The vibrational amplitude of the cavities can be enhanced to about 3 times by using phononic reflective gratings. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/17802 |
Fulltext Rights: | 未授權 |
Appears in Collections: | 應用力學研究所 |
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ntu-104-1.pdf Restricted Access | 4.75 MB | Adobe PDF |
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