電漿子式光學天線之設計與實驗驗證

Design and Experimental Verifications of Plasmonic Optical Antennas

曹修豪(Hsiu-Hao Tsao)

指導教授 ： 黃承彬

國立清華大學/電機資訊學院/光電工程研究所/碩士(2011年)

摘要

本論文利用有限差分時域法模擬三角形對天線的光譜響應與近場能量分佈，得到在波長 和 的激發下，高 的三角形對天線之增強因子將會大於高 的三角形對天線，且在近場分佈圖中，電場能量會聚集於三角形粒子與空氣接觸的頂端，其強度會隨著距離衰減，衰減程度約正比於距離的六次方倒數。考慮入射光之偏振態，電場偏振方向平行天線走向所得到的增強因子將會大於垂直天線走向。
樣品製程方面，本論文利用電子束微影術，於加速電壓 和電流 的條件下，設計並在石英基板上製作出奈米天線陣列；而量測方面，以自行架設的收集式近場掃描光學顯微鏡，配合衰減式全反射光路，利用剪切力回饋的方式量測奈米天線陣列之真實近場光學強度分佈。最後將實驗量測數據與模擬數據做一比較，無論是定性或定量分析皆有非常相近的結果。

關鍵字

奈米天線 ； 表面電漿子 ； 近場掃描光學顯微術 ； 電子束微影術 ； 有限差分時域法

並列摘要

In this work, we use finite-difference time domain method to simulate the spectral response and near-field intensity distribution of bowtie antenna and found that under the excitation of and , the enhanced factor of antenna with the height of is larger than the antenna with the height of . When studying the near-field intensity distribution, the electric energy will concentrate on the apex of bowtie antenna in the metal-air side and its magnitude will decay with increasing observation distance. The decay rate is proportional to the reciprocal of six power of distance. Considering the polarization of incident light, when polarization is parallel to antenna axis, the enhancement will be larger than the polarization perpendicular to antenna axis.
In the aspect of sample process, we utilize the electron beam lithography to design and fabricate nano-antenna array on quartz substrate under the condition of and . Then, in the aspect of measurement, we use home-made collection mode near-field scanning optical microscope with attenuated total internal reflection set-up to obtain the real near-field intensity distribution of bowtie antenna array by shear force feedback. Finally, we compare the experimental results with the simulation data, and have a very close conclusion.

並列關鍵字

antenna ； surface plasmons ； near-field scanning optical microscopy ； electron beam lithography ； finite-difference time domain method

參考文獻

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