耦合表面電漿模態之線性與非線性侷域場分析與應用於微量分子感測上之設計與驗證

The Analysis of Linear and Nonlinear Localization Characteristics of Coupled Surface Plasmon Mode and Applied to the Design and the Demonstration in Single Molecule Detection

俞文翔(Wen-Hsiang Yu)

指導教授 ： 戴朝義

國立中央大學/理學院/光電科學與工程學系/博士(2013年)

摘要

短短的數十年內，間隙表面電漿之發展已從科幻邁入真實，並於表面電漿迴路、太赫茲產生、近場光學顯微鏡、高密度資料儲存、高效率太陽能電池、單分子檢測、光熱治療與生物標籤等領域扮演了舉足輕重的角色。本論文對於間隙結構中之耦合表面電漿模態進行了線性/非線性和侷域/非侷域之全波向量特性分析，並進一步將分析結果應用於單分子之探測上。
在結構設計與分析中，「表面電漿超稜鏡」被提出用以分析空間中的角色散，可用以製作微型光譜儀，其偵測敏感度高達5.4˚/nm;「表面電漿輸送環」之研究，探索了模態分裂之起源係源自內共振腔之耦合，並被用於同時偵測奈米散射體之電極化率與位置;「無定義共振腔」之研究，重新詮釋了在金屬奈米狹縫中之Goos-Hänchen相位平移，應用於建立具有無限大增強係數與趨近於零體積之光學共振腔。「非線性拉曼增強與溫度抑制」之研究，揭發了溫度場與電磁場間在奈米粒子上之強耦合效應，調控了照射強度相依增強係數與溫度之非線性函數關係，應用於單分子感測上，可以得到合理的偵測靈敏度卻又不造成分子劣化。
實驗上，「單分子表面增強異常閃爍拉曼光譜」之研究，基於自行建立的拉曼顯微鏡，清晰的觀測了間隙表面電漿輔助誘發之單分子拉曼光譜，而其中同調閃爍之震動模態被歸因於震動模式之耦合;「在金奈米島間中之光頻率混合」之研究，基於自行建立之多色激發-探測系統，實現了小於40 fs四波混合的鬆弛時間量測;「三維光學塔柏效應」之研究，基於近場光學顯微鏡之超空間解析能力，繪製了在繞射極限下之三維干涉圖形。
本論文對於利用時空超解析光譜研究表面電漿與奈米待測物之動態行為開啟了新的道路，可作為次世代了解與控制奈米系統之參考。

關鍵字

表面電漿子學 ； 表面電漿模態

並列摘要

For the past few decades, the development of gap plasmons has been turned from science fiction into reality, and played a pivotal role in the fields of nanocircuitry, terahertz generation, near-field optical microscopy, high-density data storage, high efficiency solar cells, single molecule detection, photo-thermal therapy, and nontoxic bio-labels. This thesis presents in depth full-vectorial analysis for the linear/nonlinear and local/nonlocal properties of coupled surface plasmons in a variety of gap structures, and the application to the detection of single molecule.
In the structure design and analysis, the “plasmonic superprism” was proposed for the analysis of angular dispersion of light waves in free space. It can be readily used for the manufacture of miniaturized spectrometer with a detection sensitivity as high as 5.4˚/nm; The “plasmonic carousel” explored the origin of giant mode splitting from intracavity resonance. This effect wad found useful in simultaneously monitoring the position and the polarizability of nano-objects; the “indefinite cavity” revisits the Goos-Hänchen phase shift in a tiny metallic slit, and the peculiar resonance was applied to design an optical cavity with infinite enhancement factor and nearly zero mode; the “nonlinear Raman enhancement and temperature suppression” unraveled the strong coupling between the temperature field and electromagnetic field in metal nanoparticles. The nonlinear relationship between the temperature and the electromagnetic enhancement as a function of illumination intensity was tailored to give appropriate detection sensitivity for single molecules while avoid thermal degradation.
Experimentally, the study “anomalous blinking characteristic in single molecule surface enhanced Raman spectroscopy” based on home-built Raman microscope clearly observed the gap plasmons assisted single molecule Raman scattering. Of particular interest, the synchronous blinking in various vibrational modes was attributed to the vibronic coupling; the study “optical frequency mixing at gold nanoisland” was conducted basing on home-built multi-color pump-probe system. Four wave mixing dynamics with a temporal resolution <40 fs was relaized which is useful for nonlinear spectroscopy and bio-labeling; “three dimensional optical Talbot carpet” was demonstrated based on scanning near-field optical microscope, where 3D interference pattern beyond the diffraction limit was mapped.
This thesis opens an avenue for studying of the interactions between surface plasmons and nano-objects where the dynamics were probed by spatial-temporal resolved spectroscopy. The results will certainly benefit to the scientic society, particularly in the fields of bio-photonics and next-generation nanosystems.

並列關鍵字

Plasmonics ； Surface Plasmon Mode

參考文獻

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[1.2] L. Rayleigh “On the Dynamic Theory of Gratings,” Proc. R. Soc. London Ser. A 79, 399–416 (1907).

[1.3] L. Rayleigh “Note on the Remarkable Case of Diffraction Spectra Described by Prof. Wood,” Phil. Mag. 14, 60-65 (1907).

[1.4] W. L. Bragg “The Diffraction of Short Electromagnetic Waves by a Crystal,” Proceedings of the Cambridge Philosophical Society 17, 47-57 (1913).

[1.5] R. W. Wood “Diffraction Gratings with Controlled Groove form and Abnormal Distribution of Intensity,” Phil. Mag. 23, 310-317, (1912).