奈米金屬洞與漸變圓錐奈米結構上表面電漿子螺旋模態

Abstract

此篇研究主要討論可見光在奈米尺度的金屬洞的傳導行為及光學特性，研究的開始我們回顧文獻Chen.C.M et [3]討論奈米金屬柱的表面電漿子螺旋現象[1][4]，了解表面電漿於奈米金屬柱下的傳播特性，再來討論以理論推導、數值模擬與參考文獻為主，模擬的方法我們使用麻省理工開放軟體meep採用有限時域差分法(FDTD)數值模擬計算，並進一步研究光在系統中的波函數及色散關係，推導出光在奈米金屬洞的螺旋模態(Spiral mode)再進階做螺旋模態分析在漸變的金屬圓洞半徑結構下的電漿特性變化，以及應用於探針結構與改善。

Surface plasmons (SPs) that propagate inside metallic nanoholes have drawn a lot of research interests because they are closely related to the extraordinary optical transmission of a thin metallic film with sub-wavelength hole arrays. We based on light’s wave function and dispersion relation to get light’s “Spiral Surface Plasmon”(SSP) mode then get improve and application.

In this paper, the SSP modes inside a cylindrical nanohole with metallic surface are proposed and investigated. The single- and triple-stranded SSP modes that are composed of the fast-wave branch of the SP eigenmodes inside the metallic nanohole are demonstrated by FDTD simulation.

The SSP modes inside the tapered metallic nanoholes are also explored. The changes of spiral pitch and field energy density of SSP modes with the propagation position are observed and elucidated. Finally, the propagation of SSP modes inside a tapered metal-clad fiber with capped by a tapered metallic nanorod is examined.