光熱對流是在高光功率下使粒子能穩定的被光學鑷子捕捉的一個主要障礙。粒子被近場光學捕捉力捕捉後，往往會受到熱對流干擾使粒子隨熱對流消失於光學晶格中。在此我們示範一個方法，利用水在低溫時膨脹係數趨近於零的特性，此特性能夠有效地抑制電漿子光熱效應產生的光熱對流。
我們知道使用一個非完全對焦的高斯光束照射於一個簡單方形奈米電漿陣列時，會產生可捕捉粒子的二維光學晶格。我們觀察到這些螢光微粒在室溫下，會因為光熱效應所造成的熱對流運輸現象，粒子將隨著熱對流往液體表面移動，所以粒子一旦進入光晶格中就會消失於光晶格的表面。與之相反的，在低溫下，我們觀察到即使提高光功率，近場光學梯度力依然能夠穩定的使大小為1um的粒子被二維光學晶格捕捉，而不受到光熱對流的干擾。
因此這種低溫技術將可大大增加可用的光功率，進而提高光學鑷子捕捉微小粒子的能力。甚至可以運用在含蛋白質的生物上，避免光熱效應破壞，導致黏滯於晶片，使晶片壽命提升。

Photothermal convection has been a major obstacle for stable particle trapping in plasmonic optical tweezer at high optical power. Here we demonstrate a strategy to suppress the plasmonic photothermal convection by using near zero thermal expansion coefficient of water at low temperature. A simple square nanoplasmonic array is illuminated with a loosely Gaussian beam to produce two dimensional optical lattice for trapping of nanoparticle. We observe stable particle trapping due to near-field optical gradient forces at elevated optical power at low temperature. In contrast, at the sample optical power at room temperature, the particles will get expelled, and disappear once they enter into the optical lattice. This technique will greatly increase usable optical power and enhance the trapping capability of plasmonic optical tweezer.

誌謝 i
中文摘要 ii
Abstract iii
目錄 iv
圖目錄 vi
表目錄 ix
一、緒論 1
1-1 研究動機 1
1-2 光學鑷子 2
1-3 電漿子光學鑷子 4
1-4 文獻回顧 6
二、系統架設及電漿子光學晶格結構製程 13
2-1 光學鑷子系統架設 13
2-1-1 光學系統架設 13
2-1-2 光路校正 15
2-2 TEC冷卻系統架設 20
2-2-1 硬體架構 20
2-1-2 H-bridge電路 21
2-2-3 Arduino控制系統 23
2-1-4 溫度感測系統 25
2-2-5 鰭式散熱載台設計 26
2-3 二維奈米電漿子結構製程 27
三、實驗結果與討論 30
四、結論與未來展望 38
附錄A 雷射功率測量 39
附錄B 鰭式散熱載台設計圖 42
附錄C LabVIEW for Arduino程式碼 43
附錄D 測量電漿光晶格溫度技術 44
附錄E Matlab程式碼 46
E-1 晶格溫度分佈曲線x軸方向 46
E-2 晶格溫度分佈曲線y軸方向 47
E-3 雷射光斑的高斯曲線模擬圖 48
E-4 螢光微粒軌跡分析程式碼 49
E-5 RhodamineB亮度計算程式碼 51
參考文獻 52

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