藍相液晶為一種三維光子晶體結構，在於光子晶體發展上其被視為極具潛力之材料。一般而言，藍相液晶之晶體結構對於藍相一與藍相二分別為體心立方晶體與簡單立方晶體。非立方晶形之藍相液晶可藉由對其施加電場所形成，然而在移除電場後其即回復至原本的立方晶體之結構，如此使得藍相液晶之發展備受限制，而本研究提出一方法可成功引致不需外場協助亦可穩定存在的非立方晶形藍相液晶。在沿著[110]晶軸方向上反覆施加電場於藍相液晶後，其晶體結構逐漸由原本的立方體結構轉變為非立方結構，且不會有扭曲晶體回復的情況發生。此外，我們詳細地探討如何反覆施加電場之方式引致非立方晶形之晶體結構，同時討論不同缺陷線之組成在於引致非立方晶形所帶來的影響，這些結果亦符合我們所提出之假設。因此我們成功無需外場亦可存在的非立方晶形之光子晶體，建立於此研究結果之上，期望可開啟更多光學與光電子學相關之發展。

Blue phase is a three-dimensional photonic crystal, and is considered as a promising material for Photonics. Generally, the lattice structures of blue phase are body-centered cubic and simple cubic for BPI and BPII, respectively. In addition, the non-cubic blue phase exists only under the electric field, and it restores to the cubic blue phase upon removal of the external field. Thus, the development of blue phase is limited by this constraint. In this research, we successfully propose a method to induce the stable distorted BPLC, without the assistance of the electric field. After applying the alternative electric field by several times on [110]-oriented BPI, we find the blue phase transform to distorted BPLC without the occurrence of the restoration due to the reconstruction of configuration. Furthermore, we investigate how to utilize an electrical treatment to induce stable distorted BPLC in detail. The influence of the configuration of disclination on the inducement of stable distorted structure is also discussed. The result is coincided with our proposed model. Therefore, we expect these results can encourage the development of photonic crystals.

摘要 i
Abstract ii
List of figures vi
List of tables ix
Chapter.1 Preface 1
Chapter.2 Introduction 4
2.1 Introduction of liquid crystal 4
2.1.1 Origin and brief history 4
2.1.2 Classification 5
2.1.3 Thermotropic liquid crystal 6
2.1.3.1 Nematic phase 7
2.1.3.2 Smectic phase 8
2.1.3.3 Cholesteric phase 9
2.1.4 Related properties 11
2.1.4.1 Birefringence 11
2.1.4.2 Dielectric anisotropy 14
2.1.4.3 Elastic constant 16
2.1.4.4 Viscosity 17
2.2 Blue phase liquid crystal 19
2.2.1 Basic introduction 19
2.2.2 Lattice orientation and Miller index 21
2.2.3 Selective Bragg reflection 22
2.2.4 Identification of blue phases 24
2.2.4.1 Polarized optical microscopy (POM) 24
2.2.4.2 Reflection spectrum 25
2.2.4.3 Kossel diagram 27
2.2.5 Response of blue phases under electric fields 29
2.3Introduction of non-cubic blue phase liquid crystal 35
2.3.1 Introduction of photonic crystal 35
2.3.2 Fabrication of photonic crystal 37
2.3.3 Non-cubic photonic crystal 39
2.3.4 Electric field induced lattice transformation of blue phases 40
2.3.5 Introduction of BPX 42
2.3.6 Proposed method and scope 44
Chapter.3 Materials and experiment 48
3.1 Materials and precursors 48
3.1.1 Host liquid crystal 49
3.1.2 Chiral dopant 49
3.1.3 Monomers 50
3.2 Fabrication of cells 51
3.2.1 Preparation of substrates 51
3.2.2 Process of homogeneous alignment layers 52
3.2.3 Fabrication of samples of blue phases 53
3.3 Experiment 53
Chapter.4 Results and discussion 55
4.1 Inducement of stable distorted BPLCs 55
4.1.1 Phase sequence of a monomer-doped BPLC 55
4.1.2 Response of a monomer-doped BPLC under an electric field 57
4.1.3 Electrical treatment on a monomer-doped BPLC 58
4.2 Evidence of non-cubic BPLC 60
4.3 How to utilize an electrical treatment 62
4.3.1 Influence of different durations of an electrical treatment 62
4.3.2 Influence of different cycles of an electrical treatment 63
4.4 Influence of lattice structures’ difference 66
4.4.1 Electrical treatment on BPI at different temperatures 66
4.4.2 Electrical treatment on BPII at different temperatures 68
4.5 Field-dependence modulation 70
4.6 Material: Assist to stable distorted structure 72
4.6.1 Failure of inducing stable distorted structures in pristine BPLCs 72
4.6.2 Evidence of thermal effect 75
4.6.3 Electrical treatment on monomer-doped BPLC of different ratios 76
Chapter.5 Conclusion and prospect 80
5.1 Conclusion 80
5.2 Prospect 81
Reference 82

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