臺灣博碩士論文加值系統

基於非輻射場的產生和探測，掃瞄式近場光學顯微儀（Near-field scanning optical microscopy（NSOM））能夠以超繞射極限的分辨率進行成像。本文採用時域有限差分(FDTD)方法，應用至近場光學的領域，有系統的研究光在光纖探針中的傳播行為與分佈特性，分析錐度、孔徑、探針內部介質的折射率等參數對通光效率的影響，為探針的製備上提供了理論與最佳化設計的依據。本文在內容上分為以下四個主題：
一、建立一套求解電磁散射問題的數學模式，並從數值方法特性的分析，構建出最佳化之格式與程式設計之技巧。
二、研究無限大理想導體平面上奈米尺度圓孔和方孔之近場分佈特性，以作為分析複雜幾何形貌之準備。
三、比較裸光纖探針及鍍金屬膜探針的近場分佈特性，模擬結果顯示：裸光纖探針的側面洩漏光比針尖出射光強的多；奈米圓孔和金屬膜探針的近場分佈相似；由於邊界突變使得入射偏振光從探針（或小孔）出射後產生的兩個垂直偏振分量，導致孔徑邊緣的場增強。
四、研究錐度、孔徑、探針內部介質的折射率、樣品與探針間距、樣品折射率的大小等對金屬膜探針通光效率的影響。

The subwavelength resolution of near field scanning optical microscopes (NSOM) is based upon the detection of the static radiation in near field. No diffraction effect happens enable the NSOM to have ultrahigh resolution in imaging. In this dissertation , the near-field distribution of fiber-optic probes is investigated. The numerical method known as finite-difference time domain（FDTD） is introduced into near-field optics. The effects of various taper angles, tip diameters and the refractive indices of the inner dielectric material , and the throughput of metal-coated probes are investigated .Results of the calculations provide a direct theoretical basis for probe optimization.
The near-field distribution of small apertures of round and square shape in an infinite metal plane, and the metal-coated and uncoated fiber-optic probes are studied systematically using our FDTD method. It is found that the electric field leaking from the conic side is much stronger than the output of the tip apex for uncoated probes. Results of an aperture on a infinite metal plane show similar near-field distribution to that of a coated fiber probe. Due to the boundary conditions at the interface, the polarized incident wave , after exiting the apex of the probe, produces two perpendicularity polarized electric-field components , which enhance the field at boundary of the tip aperture. The effect of depolarization of coated probes and square apertures is much more obvious than that of uncoated ones and round apertures, respectively. The influence of taper angle, tip diameter and refractive index of inner dielectric material of the coated probes on the throughput is studied with FDTD method as well.

第一章前言 1
1.1.電磁散射問題與近場光學模擬之關聯性 1
1.2.近場光學模擬方法之介紹 2
1.3.研究動機 5
1.4.論文章節概要 5
第二章時域有限差分法之數學模 7式
2.1.理論背景與公式推導 7
2.2.FDTD法之數學模式 7
2.3.數值分析應注意之事項 10
2.4.計算機程式設計 18
第三章無限大導體屏上奈米小孔的近場分佈 37
3.1.消散場與傳播場37
3.2理想導體屏上小孔的近場分佈 39
3.3實際導體屏上圓形小孔的近場分佈 41
3.4.偏振態對場分佈的影響 42
第四章 光纖探針的場分佈 57
4.1.裸光纖探針之模擬分析 57
4.2.鍍鋁膜探針之模擬分析 58
4.3.探針製作上之改良建議 59
4.4.影響金屬模探針的場分佈參數 59
第五章結論 74
參考資料 76

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