介電奈米表面結構與金屬材料之互動所引致指向性出射研究：奈米直寫儀光學頭之創新設計

Directional Beaming by Interaction of Dielectric Nano Surface Structure and Metal : Design for Fabrication of Nanowriter Optical Head

陳怡君(Yi-Chun Chen)

指導教授 ： 李世光 ； 葉超雄

國立臺灣大學/工學院/應用力學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.01241

摘要

本論文以Ebbesen等人發現的異常穿透現象與指向性現象為基礎，提出二個創新的指向性光學頭設計：非金屬光學頭與雙孔洞光學頭。具指向性的光學頭結構是金屬薄膜上，具有一次波長孔洞使光通過，同時在光的出射面有次波長的週期性表面結構，表面結構的不同週期可使出射光聚焦於特定角度。此重要物理現象產生的原因目前仍未有定論，故本文藉由創新光學頭的架構，討論異常穿透現象與指向性現象的產生機制。
非金屬光學頭的結構是金屬薄膜上具有非金屬表面光柵。論文中以模擬及實驗，證明非金屬光學頭的可行性。由探討非金屬光學頭產生指向性現象的原因，清楚說明背後的物理機制，發現表面電漿在非金屬光學頭的指向性現象扮演重要角色。此外，非金屬光學頭物理機制的討論，亦為金屬光學頭指向性機制的討論依據。設計非金屬光學頭的目的是提供指向性光學頭大量製造的方式，文中提出表面電漿對指向性現象的影響，提供在不同波長下設計指向性光學頭的材料選擇依據；而光學頭的出射角度可藉由反射式光柵最小反射率得到；因此本文完成非金屬光學頭之完整設計流程，具有工程應用的價值。
本論文另一創新設計是雙孔洞的光學頭。雙孔洞光學頭藉由改變二個孔洞的間距而得到不同的聚光距離，並利用二道出射光交錯後的干涉，在交錯點得到次波長尺寸光束，顯示奈米光學系統具有超越傳統光學系統聚焦能力之可能。

關鍵字

奈米結構薄膜 ； 光學微影 ； 表面電漿

並列摘要

Based on the Extraordinary transmission and directional beaming phenomena proposed by Ebbesen et al, novel optical head structures are presented.
Non-metal optical head composed of dielectric surface grating on a metallic thin film was proposed. In this thesis, simulation tools and experiments were carried out to prove that non-metal optical head works as metal optical head previously reported. Analyzing the simulation results, surface plasma is shown to play an important role in the directional beaming phenomenon. The main reason for designing non-metal optical head proposed in this thesis is for mass production possibilities. Knowing the mechanism which drives the directional beaming phenomenon for non-metal optical head, design rule for desired non-metal optical head is presented.
Another novel optical design proposed is double slits optical head. Light emerging from the two slits cross at the desired focal length, which is decided by the distance between the two slits. Also, the two beams interference to become a subwavelength light spot. Therefore, by designing the surface structure of double slits optical head, it is possible to achieve subwavelength focal spot with unprecedented focal length that appears to bypass the Rayleigh criteria.

並列關鍵字

Nanostructured film ； surface plasmon ； photolithography

參考文獻

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Barnes, W. L., et. al., “Surface plasmon subwavelength optics,” Nature, 424, 824, 2003.

Barnes, W. L., Murray, W. A., et. al., “Surface Plamon Polaritons and Their Role in the Enhanced Transmission of Light through Periodic Arrays of Subwavelength Holes in a Metal Film,” Phys. Rev. Lett. 92, 10, 107401, 2004.

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