共振是自然界一個基本物理過程。特別是，在納米尺度上的光頻電磁諧振產生顯著的場增強，提供了一種手段來影響和控制光與物質的相互作用。例如，巨大的場增強使表面增強拉曼散射具有探測單個分子的靈敏度。此外，場增強可以使發光二極體具有更高亮度高，但輸入功率更低。雖然場增強在一些關鍵技術領域大有前途，有許多挑戰仍有待解決。由於場增強是如此強烈地依賴系統的幾可形狀即使稍作修改可以導致大的結果變化，因此理解幾何結構如何影響場增強和可重複的製造這些車前壽是最重要的。因此本論文致力於設計，製造和貴金屬如銀或金的一維結構的表面上生成的場增強特性。 / 首先對s-偏振下一維金屬光栅產生的場增強使用嚴格購合波分析(RCWA) 進行了設計和優化。優化後，在514nm 波長最強的增強因數是9.7 。製作了一維光栅並進行角度相關的反射率測量，實驗結果與理論計算相符。 / 對一種新型利用表面等離子激元的呻吟加強電場的單縫桔構進行了研究。首先利用用衰減全反射搞合在50 納米厚的金屬薄膜上產生sp恥，隨後利用spps 驅動這一狹縫。結果發現縫內場增強至少3 倍於狹縫附近的等離子激元背景。其增強機理用數值和分析的方法進行理論研究。 / 提出了兩種新型的製造高深寬比納米縫隙的簡便方法。一個是在飯有金膜的薄玻璃上製造裂紋，獲得了寬度小於5nm 具有一定平整度的抗縫，通過掃描電子顯微鏡圖像和共焦雙光子發射(CTPE) 光譜和時間域有限差分模擬的對比得到了確認。另一種是對鍍有金膜的柔性基底進行疲勞彎折，獲得了大量狹縫。觀察到CTPE 和二次諧波產生從這些縫中產生。 / 採用電子束光刻製作了納米縫並使用CTPE 進行了表徵。提出一種新方法對激發波長和發射波長的增強因數進行了分解。發現脈衝錯射能調整EBL 樣品的共振波長到錯射波長。提出了一種機制解釋這一現像。進一步實驗表明這是一種製造任意共振波長場增強熱點的有用方法。 / Resonance may be one of the most fundamental rules of nature. Electromagnetic resonance at nanometer scale could produce a giant field enhancement at optical frequency, providing a way to measure and control the process of atoms and molecules at single molecule scale. For example, the giant field enhancement would provide single molecule sensitivity for Raman scattering, which provides unique tools in measuring the quantity in extremely low concentration. In addition, light-emitting diodes could have high brightness but low input power that would be revolutionary in the optoelectronic industry. Although light enhancement is promising in several key technology areas, there are several challenges remain to be tackled. In particular, since the field enhancement is so strongly geometry dependent that slight modification of the geometry can lead to large variations in the outcome, a thorough understanding in how the geometry of the structure affects the field enhancement and creating proper methods to fabricate these structures reproducibly is of most importance. This thesis is devoted to design, fabrication and characterization of field enhancement generated on the surface of noble metals such as silver or gold with 1D structure. / The s-polarized field enhancement arISIng from one-dimensional metal gratings IS designed and optimized by using Rigorous Coupling Wave Analysis (RCWA). After optimization, the strongest enhancement factor is found to be 9.7 for 514nm wavelength light. The theoretical results are confirmed by angle-dependent reflectivity measurements and the experimental results are found to support the theory. / A novel single slit structure employing sUlface plasmon polaritons (SPPs) for enhancing the electric field is studied. SPPs are first generated on a 50 nm thick metal film using attenuated total reflection coupling, and they are subsequently coupled to the cavity mode induced by the single slit. As a result, the field enhancement is found at least 3 times the surface plasmon background adjacent to the slit, as predicted by using RCWA. The mechanism for enhancement is theoretically studied both numerically and analytically. / Two novel convenient methods for fabricating nanoslits with high aspect ratio are proposed. One is creating nanoslits by cracking the thin glass substrates with metal film. Sub-Snm wide slits with fair uniformity are created, as confirmed by Scanning Electron Microscopy images and comparing the Confocal Two Photon Emission (CTPE) spectroscopy with finite difference in time domain simulations. The other is creating slits by fatiguing the metal film on a flexible substrate. Enhanced CTPE and second harmonic generation are observed arising from these less than 20nm wide slits. / Nanoslits fabricated using Electron Beam Lithography (EBL) are characterized using CTPE. The overall emission enhancement of excitation and collection wavelengths is separated by a proposed method. It is surprisingly found that the pulsing laser can tune the resonant wavelength of the EBL samples to the laser wavelength. A mechanism is proposed for this phenomenon. It is shown this can be developed into a tool to fabricate field enhancement hot spots. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Liu, Benliang = 用貴金屬結構增強場強 / 劉本良. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 133-137). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Liu, Benliang = Yong gui jin shu jie gou zeng qiang chang qiang / Liu Benliang. / Acknowledgement --- p.i / Abstract --- p.ii / 摘要 --- p.iv / List of figures --- p.1 / Chapter 1 --- Overview --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Applications of field enhancement --- p.1 / Chapter 1.2.1 --- Surface enhanced Raman scattering --- p.1 / Chapter 1.2.2 --- Enhanced luminescence --- p.4 / Chapter 1.3 --- Fundamentals of field enhancement --- p.5 / Chapter 1.3.1 --- The Maxwell's equations --- p.6 / Chapter 1.3.2 --- Boundary conditions --- p.8 / Chapter 1.3.3 --- Phase matching condition --- p.10 / Chapter 1.3.4 --- Dipole --- p.11 / Chapter 1.3.5 --- Purcell factor --- p.12 / Chapter 1.3.6 --- Mode and mode interaction --- p.13 / Chapter 1.3.7 --- Surface plasmon resonance --- p.14 / Chapter 1.3.8 --- Fabry-Perot cavity resonance --- p.16 / Chapter 1.4 --- Overview of the nanofabrication methods of metal structures for field enhancement --- p.17 / Chapter 1.4.1 --- Photolithography --- p.18 / Chapter 1.4.2 --- Electron Beam Lithography --- p.20 / Chapter 1.4.3 --- Focused ion beam --- p.21 / Chapter 1.4.4 --- Summary --- p.21 / Chapter 2 --- Methods of simulation --- p.26 / Chapter 2.1 --- Rigorous coupled wave analysis framework --- p.26 / Chapter 2.1.1 --- FormulaofRCWA --- p.26 / Chapter 2.1.2 --- Expression ofMaxwell's equations in Fourier space --- p.27 / Chapter 2.1.3 --- Numerical shooting method --- p.29 / Chapter 2.1.4 --- Reflection efficiency, transmission efficiency and absorption --- p.32 / Chapter 2.1.5 --- Convergence test of the RCWA simulation --- p.33 / Chapter 2.2 --- Finite difference in time domain --- p.34 / Chapter 2.2.1 --- Formulations of FDTD --- p.34 / Chapter 2.2.2 --- Dispersion of dielectric constant --- p.35 / Chapter 2.2.3 --- Boundary conditions and excitation sources --- p.37 / Chapter 3 --- Investigation of s-polarized resonance on 1D grating --- p.40 / Chapter 3.1 --- Introduction --- p.40 / Chapter 3.2 --- Theoretical results of the s-polarized resonance in the 1D grating --- p.41 / Chapter 3.3 --- Discussion of the theoretical results --- p.47 / Chapter 3.3.1 --- Origination of the s-polarized resonance modes --- p.47 / Chapter 3.3.2 --- Position discrepancy between absorption peaks and reflection dips --- p.48 / Chapter 3.3.3 --- Absorption beyond the cutoff wavelength of reflectance --- p.48 / Chapter 3.3.4 --- Absorption wavelength dependency on the periodicity --- p.50 / Chapter 3.4 --- Effects of parameters on absorption and electric field --- p.50 / Chapter 3.5 --- Optimization the s-polarized resonance for field enhancement --- p.54 / Chapter 3.6 --- Angle dependency of the optimized resonant mode --- p.55 / Chapter 3.7 --- Grating preparation and characterization --- p.57 / Chapter 3.8 --- Experimental results and discussion --- p.59 / Chapter 3.9 --- Summary --- p.73 / Reference --- p.74 / Chapter 4 --- Fabricating and characterizing nanoslit-shaped resonant cavity --- p.75 / Chapter 4.1 --- Introduction --- p.75 / Chapter 4.2 --- Confocal two photon emission measurement --- p.78 / Chapter 4.2.1 --- Background --- p.78 / Chapter 4.2.2 --- Polarization dependence of the confocal system --- p.79 / Chapter 4.3 --- Decomposition of excitation and collection TPL enhancement --- p.81 / Chapter 4.4 --- Fabrication and characterization of slits by cracking glass substrate --- p.83 / Chapter 4.4.1 --- Fabrication of nanoslits by cracking glass --- p.83 / Chapter 4.4.2 --- Characterization of the nanoslits by cracking glass substrates --- p.86 / Chapter 4.4.2.1 --- Two-photon emission from rough slits 86 / Chapter 4.4.2.2 --- Location dependence of the two-photon emission --- p.87 / Chapter 4.4.2.3 --- Relation between reflection and two-photon emission --- p.88 / Chapter 4.4.2.4 --- Wavelength dependence ofTPLfrom the slits by cracking glass --- p.89 / Chapter 4.4.3 --- Discussion --- p.97 / Chapter 4.4.4 --- Summary --- p.98 / Chapter 4.5 --- Fabrication and characterization of nanoslits by fatigue --- p.98 / Chapter 4.5.1 --- Fabrication ofnanoslits by fatigue --- p.98 / Chapter 4.5.2 --- Characterization ofnanoslits by fatigue --- p.100 / Chapter 4.5.3 --- Discussion --- p.105 / Chapter 4.6 --- Two photon emission from nanoslits by EBL --- p.106 / Chapter 4.6.1 --- Sample preparation --- p.107 / Chapter 4.6.2 --- Characterization of the slits made by Electron Beam Lithography --- p.109 / Chapter 4.6.2.1 --- Reflected light extinction and two photon emission --- p.109 / Chapter 4.6.2.2 --- Wavelength dependence of TPL enhancement --- p.120 / Chapter 4.6.2.3 --- Laser modification of resonant wavelength of the cavity --- p.124 / Chapter 4.6.2.4 --- Discussion --- p.126 / Chapter 4.6.3 --- Summary --- p.132 / Chapter 5 --- Conclusion --- p.138
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_328028 |
| Date | January 2012 |
| Contributors | Liu, Benliang, Chinese University of Hong Kong Graduate School. Division of Materials Science and Engineering. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, bibliography |
| Format | electronic resource, electronic resource, remote, 1 online resource (ix, 139 leaves) : ill. (chiefly col.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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