次波長光柵形狀影響表面電漿共振之研究：奈米直寫儀光學頭之開發及相關應用

The Influence of Subwavelength Grating Profiles to Surface Plasmon Resonance: Development of Nanowriter Optical Head and Related Applications

周佩廷(Pei-Ting Chou)

指導教授 ： 吳光鐘 ； 李世光

國立臺灣大學/工學院/應用力學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.01535

摘要

光柵耦合為激發表面電漿共振的一種主要方法，本論文基於Ebbesen等人所提出由表面電漿共振引發之異常穿透現象，針對不同材質及表面輪廓形狀的光柵進行研究，以了解其改變對於產生表面電漿共振之影響。並且利用在此研究的發現，期盼能對於奈米直寫儀光學頭的設計及其他相關應用上作出貢獻。
本論文在模擬方面，以嚴格耦合波分析及有限時域差分法計算光柵耦合表面電漿時的反射頻譜及電磁場模態，並且求出不同表面輪廓光柵下的表面電漿色散曲線及耦合效率，我們認為非金屬表面光柵可以視為一等效介質層來處理，而對於金屬表面光柵，我們發現漸變式光柵的表面電漿共振條件異於二維光柵，故在不同光柵深度下，光柵的耦合效率及能隙寬度會有所不同，且在不同波長的入射光之下，電磁場強度的分佈會有所不同，經由以上模擬我們順利得到設計奈米直寫儀光學頭或相關光電元件時的參考資訊。
在實驗方面，則使用電子束微影法製作漸變式光柵，並且配合相關製程可製作金屬及非金屬表面光柵，進而討論奈米直寫儀光學頭之製程。並且配合溼蝕刻方式製造三角形奈米壓印母模，以增加使用奈米壓印技術來製造奈米直寫儀光學頭或其他相關應用之可能性。

關鍵字

表面電漿 ； 光柵 ； 奈米直寫儀

並列摘要

Grating coupling is a major method to excite surface plasmon resonance; this thesis took the extraordinary transmission phenomenon first proposed by Ebbesen et al. as the starting point to study gratings of different materials and various profiles in order to understand the influence of these changes on surface plasmon resonance. It is anticipated to utilize parameters learned during the course of this research to facilitate the design of nanowriter optical head and other related applications.
In simulations, we use rigorous coupled wave analysis (RCWA) and finite difference time domain (FDTD) to calculate the reflection spectrum and electromagnetic mode of surface plasmons, both of which is coupled by using gratings. The surface plasmon dispersion curve and coupling efficiency under different grating profiles were successfully calculated. We consider the non-metal surface gratings as a homogeneous dielectric layer by using effective medium theory. For metal surface gratings, we found the surface plasmon resonance condition of gradient gratings is different to binary gratings, thus the coupling efficiency and band gap width of gratings under different grating depths will be different. The distribution of electromagnetic field under different wavelength of light will be different. More specifically, the coupling efficiencies and band gap width under different grating depth were found to be different. We can obtain the design criterion of optical head and other optical devices through the above simulations.
In experiments, we use electron beam lithography to make the gradient gratings, and produce metal and non-metal surface gratings with proper fabrication process. The fabrication process of nanowriter optical head was then detailed. We also take advantage of wet etching to manufacture the triangular nanoimprint mold with an attempt to reach the mass production goal of nanowriter optical head and other applications by using nanoimprint techniques.

並列關鍵字

surface plasmons ； gratings ； Nanowriter

參考文獻

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