膽固醇液晶因為其分子呈現週期性的螺旋結構排列，故可視為“一維的光子晶體”，利用固態物理的能階理論來解釋，光在光子晶體中的分佈與電子在晶體內的分佈是非常像的。而膽固醇液晶具有光子晶體的能隙特性，對應於反射頻譜中的反射波長邊緣，因此光子在能隙邊緣全反射，如同一共振腔的結構。當加入雷射染料於膽固醇液晶的樣品中，在Nd:YAG脈衝雷射的激發下，雷射染料的螢光光譜與膽固醇液晶的反射頻譜適當的重疊，在反射波長邊緣有增益的作用，所以沿螺旋軸的方向產生出雷射光。本論文中，利用自粹的有機染料葉綠素作為雷射染料摻雜膽固醇液晶，比較不同濃度葉綠素的螢光，其中以1 wt%濃度的葉綠素摻雜液晶的螢光強度最高。本實驗已成功的激發出不同濃度的葉綠素摻雜膽固醇液晶雷射，並量測出液晶雷射的閥止能量約為1.2 mJ/pulse，以及雷射的半高寬約為3.9 nm。利用葉綠素的生物相容性，可以作為有機生物性雷射的開端，並加以研究、應用。

The cholesteric liquid crystals (CLCs) can be regard as an one-dimensional (1-D) photonic crystal (PC) because of the spatially-periodic dielectric structure. According to the band theory of solid state physics, the group velocity tends to zero at the photonic band edge (PBG) of the PC resulting in the photonic can be totally reflection at the PBG. The band edge of the CLC’s reflection spectra is similar to the PBG. Therefore the CLCs can be used to be the laser cavity. When the laser dye doped into CLCs, the lasing can be produced by the Nd:YAG pulsed laser. This work proposes a biological laser with the self-extract chlorophyll as an organic laser dye doped into CLCs. The results show that the CLCs with 1wt% chlorophyll exist the highest fluorescence emission. The lasing of biological laser with various concentration of chlorophyll are also successfully generated in this work. The threshold energy and the full width at half maximum of biological laser about 1.2mJ/pulse and 3.9 nm, respectively. With the biocompatible of chlorophyll, the biological laser has great potential in many applications.

論文審定書 i
致 謝 ii
摘 要 iii
Abstract iv
目 錄 v
圖次 vii
表次 ix
第一章 簡介 1
1.1 前言 1
1.2 液晶簡介 2
1.2.1 何謂液晶 2
1.2.2 液晶的起源 3
1.2.3 液晶的分類 4
1.3 液晶物理特性 10
1.3.1 液晶的介電異向性 10
1.3.2 液晶的秩序參數 12
1.3.3 液晶的光學異向性 13
1.3.4 液晶之連續彈性體理論 15
第二章 相關理論 16
2.1 雷射特性及原理 16
2.2 膽固醇液晶的光學特性 21
2.3 膽固醇液晶之一維光子晶體 23
2.4 摻雜雷射染料之膽固醇液晶雷射 25
第三章 樣品製作與實驗架設 27
3.1 葉綠素物理特性與吸收、螢光量測 27
3.1.1葉綠素物理特性 27
3.1.2葉綠素的萃取步驟 28
3.1.3葉綠素吸收及螢光的量測 30
3.2 膽固醇液晶的配製 32
3.3 樣品的製作 34
3.4 實驗架設 35
3.4.1 空樣品盒厚度量測 35
3.4.2 膽固醇液晶的雷射頻譜量測 35
第四章 實驗結果與討論 37
4.1摻雜不同濃度的葉綠素螢光及吸收 37
4.2 摻雜不同濃度的葉綠素液晶雷射 39
4.3 葉綠素液晶雷射的臨界能量及半高寬量測 43
第五章 總結與未來展望 45
參考文獻 46

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