本論文利用Z-scan量測技術研究石墨烯飽和吸收體(graphene saturable absorber)之非線性光學性質。本研究所使用的光源為二倍頻、Q-開關以及鎖模的摻釹釔鋁石榴石雷射系統(frequency doubled, Q-switched and mode-locked Nd:YAG laser)。在樣品的方面，利用了化學氣相沉積法(Chemical Vapor Deposition, CVD)生長不同層數的原子層石墨烯，分別有1、8及16層三種。
由超快皮秒級、波長532nm的Nd:YAG雷射入射至上述三種不同層數的樣品上，並改變不同的雷射脈衝的能量來進行量測，觀察其不同的非線性光學的效應。透過Z-scan實驗技術，量測到不同層數的石墨烯材料之非線性吸收及非線性折射光學參數。由實驗結果分析，量測到非線性吸收係數α(I)與非線性折射係數n(I)的範圍分別為0.468到3.563 (108 cm-1)及0.733到5.506 (108 cm-1)，相較於其他半導體材料，化學氣相沉積法生長的石墨烯具有較大的非線性參數值。並發現我們的樣品為雙光子吸收的可能性不高，主要吸收來源為單光子吸收達到飽和所造成，但若高層數或不完善的石墨烯在能量大於40 GW/cm2時，雙光子吸收的機制有可能介入。

In the thesis, we used Z-scan technique to study the nonlinear optical properties of graphene saturable absorber. The light source employed in this study is frequency doubled, Q-switched and mode-locked Nd:YAG laser. As for the samples, we took advantage of CVD method to grow atomic layer graphene, and acquired different layers, which are 1-, 8-, and 16-layers.
By injecting an ultrafast, picosecond, 532 nm wavelength Nd:YAG laser into the above-mentioned three samples, and using different laser pulse energies to measure and investigating various nonlinear optical effects of graphene. Through Z-scan experiment, we measured the nonlinear absorption and nonlinear refractive optical coefficient for different layers graphene material.
As a result, the nonlinear absorption coefficient α(I) and nonlinear refractive index n(I) are obtained as 0.468 to 3.563 (108 cm-1) and 0.733 to 5.506 (108 cm-1), respectively. Compared with other semiconductor materials, graphene grown by CVD method has large nonlinear parameters. In addition, we concluded that the nonlinear effects might not be resulted from two photon absorption. The main source of absorption is the saturation of single photon absorption. But for graphene with more layers or defects under intensity exceeds 40 GW/cm2, TPA mechanism might be involved.

中文論文審定書 i
英文論文審定書 ii
致謝 iii
摘要 iv
Abstract v
目錄 vi
圖目錄 ix
表目錄 xii

第一章 緒論 1
1.1 研究背景 1
1.2 研究目的 2
1.3 論文架構 5

第二章 理論概述 6
2.1 奈米石墨烯材料 6
2.1.1 石墨烯簡介 6
2.1.2 石墨烯的能帶 7
2.1.3 結構分析 11
2.1.4 光電應用 16
2.2 非線性的光傳播 17
2.2.1 光傳播方程式 17
2.2.1.1 線性吸收與折射 22
2.2.1.2 非線性吸收與折射 23
2.2.2 非線性光學 24
2.2.2.1 三階非線性光學 24
2.2.2.2 高階非線性光學 26
2.2.3 飽和吸收(SA) 27
2.2.4 Z-scan理論 29

第三章 樣品製備與實驗架設 35
3.1 石墨烯樣品製備 35
3.1.1 石墨烯製程-化學氣相沉積法 35
3.1.2 石墨烯轉印 36
3.2 實驗儀器架設與相關量測技術 38
3.2.1 雷射系統 38
3.2.2 針孔掃描技術 39
3.2.3 自相干儀量測技術 40
3.2.4 Z-scan技術 42

第四章 實驗結果與分析 48
4.1 石墨烯的光學特性 48
4.2 Z-scan量測結果 54

第五章 結論與未來展望 66
5.1 結論 66
5.2 未來展望 68

參考文獻 69

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