臺灣博碩士論文加值系統

本論文以近年來全球研究團隊所注目的新物理現象－異常穿透及指向性現象為研究基礎，提出金屬層介電光學頭於指向性的物理機制與最佳化設計法則，並藉由近場光學實驗方式驗證此光學頭具有在遠場範圍保持次波長光點之能力。
金屬層介電光學頭的結構是於金屬薄膜上製作次波長等級的奈米光柵。有鑑於全金屬光學頭製作上的限制，介電光柵結構以其各項優點及製作彈性，成為光學頭大量製造的發展可能。此光學頭以創新設計所提出，並初步觀察其具指向性，本論文將是對於光學頭各子系統的物理機制與潛在能力進行探究。首先提出以嚴格耦合波分析法透過新式模擬模型，以還原介電光學頭的異常物理現象－穿透量與指向性，且能夠獲得有意義的資訊與直接觀察到光學頭的行為。並基於所提出的模型以求證表面電漿耦合作用，與表面電漿波存在於光學頭各子系統的模式。本論文已建立出利用嚴格耦合波分析與有限差分時域法所得之結果的關聯性，以確定表面電漿波與光學頭表面結構之繞射現象所引致指向行為。另外，亦針對介電光學的指向性提出最佳化法則，強調波長選擇與週期設計的重要性。
實驗上採用電子束微影製作光學頭以達成模擬預測與實驗一致的結果，進而確定指向性最佳化法則的正確性與實用價值。另一突破性的實驗即透過近場光學的方式，觀察介電光學頭指向光束的特性，證實金屬層介電光學頭具有於遠場範圍仍保持次波長光點之聚焦能力。

Based on the new physical phenomena－extraordinary transmission and directional beaming phenomena, the physical origin and optimization rule of dielectric optical head have been proposed in this thesis. And it has been verified that the optical head can produce a confined emitted beam in far field and suppress the decay of intensity simultaneously.
Dielectric optical head is composed of dielectric grating layer constructed on a thin gold film deposited onto the glass substrate. In view of the limitation to fabricate nano-scaled metallic structure, dielectric grating can be flexibly manufactured via various processes, such as nanoimprint for mass production. In this thesis, a new simulation model proposed on rigorous coupled wave analysis (RCWA) has been utilized to explore the extraordinary transmission and directional beaming phenomena of the dielectric optical head. More significant results can be obtained through the new simulation model, which requires fewer computations efforts. The optimization rule proposed for directional beaming emphasizes the importance of selecting wavelength and period of grating. This research also draws the relation between the simulated results from rigorous coupled wave analysis and finite difference time domain (FDTD) method to confirm the surface plasmon wave involved in diffraction.
Experimental results obtained from the optical head developed based on the e-beam lithography fabricated dielectric grating agree well with the simulated results obtained by using the optimization design. Besides, it is verified for the first time that the dielectric optical head can produce a subwavelength beam in far field and suppress the decay of intensity simultaneously as that of the metal head published previously.

謝誌 i
中文摘要 iii
Abstract iv
目錄 vi
圖目錄 ix
表目錄 xiii
第 1 章 緒論 1
1.1 前言與研究動機 1
1.2 論文架構 6
第 2 章 理論 7
2.1 物理極限 7
2.1.1 遠場光學與繞射極限 7
2.1.2 近場光學之限制 8
2.2 新的物理現象 11
2.2.1 異常穿透現象 11
2.2.2 指向性現象 16
2.3 金屬層介電光學頭原理 20
2.3.1 表面電漿波 20
2.3.2 有效介質理論 23
2.3.3 介電光學頭機制 26
第 3 章 模擬與分析 31
3.1 金屬介電光學頭與表面電漿耦合 32
3.2 指向性現象分析 38
3.2.1 新式模擬模型 38
3.2.2 狹縫分離程度之影響 42
3.2.3 指向性與異常穿透現象 43
3.2.3.1 零階射出面之指向性 43
3.2.3.2 非零階射出面之指向性 47
3.3 狹縫尺寸與介電結構深度之影響 54
3.3.1 光學頭之狹縫長度 54
3.3.2 光學頭之表面介電結構深度 57
3.3.3 光學頭之狹縫寬度 60
3.4 嚴格耦合波分析與有限差分時域法之模擬 62
3.5 金屬介電光學頭之最佳化 66
3.5.1 光學頭能量 66
3.5.2 光學頭指向性 67
3.6 金屬介電光學頭與表面電漿子能隙 72
3.6.1 介電結構層具高折射率 72
3.6.2 介電光學頭之表面電漿波能隙 73
第 4 章 實驗結果 79
4.1 光學頭製作流程 80
4.1.1 電子束微影術 80
4.1.2 奈米壓印術 83
4.2 光學頭指向性量測結果 86
4.2.1 電子束微影之光學頭量測 86
4.2.2 奈米壓印術之光學頭量測 92
4.3 光學頭最佳化量測結果 96
4.4 近場光學量測結果 100
第 5 章 結論與展望 108
5.1 結論 108
5.2 展望與未來目標 109
5.2.1 介電光學頭之機制 109
5.2.2 介電光學頭之製作與實驗量測 110
參考文獻 113

Chap. 1
[1]http://nano.nchc.org.tw/aboutnano.php（奈米科學網）
[2]http://nano.nsc.gov.tw/main/1/1_01.html（科技年鑑奈米網）
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[8]H. J. Lezec, et al, “Beaming Light from a Subwavelength Aperture,” Science, 297, 820, 2002.
[9]李正中, “薄膜光學與鍍膜技術”, 藝軒圖書出版社, 1999.

Chap. 2
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[19] Fadi Issam Baida, et al., ”Enhanced confined light transmission by single subwavelength apertures in metallic films,” Applied Optics, Vol. 42, No. 34, December 1, 2003.
[20] K. Tanaka and M. Tanaka, “Simulation of an aperture in the thick metallic screen that gives high intensity and small spot size using surface plasmon polariton,” J. Microsc., Vol. 210, June 3, 2003.
[21] K. Tanaka and M. Tanaka, “Simulation of confined and enhanced optical near-field for an I-shaped aperture in a pyramidal structure on a thick metallic screen,” J. Appl. Phys., Vol. 95, No. 7, April 1, 2004.
[22] K. Tanaka and M. Tanaka, “Optimized computer-aided design of I-shaped subwavelength aperture for high intensity and small spot size,” Optics Communications, 233, 231-244, January 16, 2004.
[23] Vitality Lomakin, et al., “Enhanced Transmission Through Two-Period Arrays of Subwavelength Holes,” IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS, Vol. 14, No. 7, July, 2004.
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[25] S Sena Akarca-Biyikli, et al., “Resonant excitation of surface plasmons in one-dimensional metallic grating structures at microwave frequencies,” J. Opt. A: Pure Appl. Opt. 7, January 20, 2005.
[26] H. J. Lezec, et al, “Beaming Light from a Subwavelength Aperture,” Science, 297, 820, 2002.
[27] Esteban Moreno, et al., “Enhanced transmission and beaming of light via photonic crystal surface modes,” Phys. Rev. B 69, March 9, 2004.
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[32] M. Born, and E. Wolf, Principles of Optics, Cambridge University Press, Cambridge, UK, 2002.

Chap. 3
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[40] J. B. Pendry, et al., “Transmission Resonances on Metallic Gratings with Very Narrow Slits,” Phys. Rev. Lett., Vol. 83, No. 14, October 4, 1999.


Chap. 4
[41] 李鎮瑋, 一步成型奈米壓印及模具之介電光學頭設計與研製, 國立台灣大學工程科學及海洋工程所碩士論文, 2005.

Chap. 5
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