空間光調制器(spatial light modulator ; SLM)是一個可將入射光束在空間上不同的位置調制出不同相位、振幅或偏振狀態之光電元件。SLM具有空間中高解析度的調制能力，並且可以藉由電腦輸入訊號，並行地控制每一個像素的調制效果，在空間中給予不同的相位變化，可以對光場進行調控，而此種動態調制的元件開啟了諸多應用的發展。
本研究分為兩大部分：分別為改善SLM調制的速度及與偏振相關的特性和光渦旋之應用。首先是改善的材料，市面上所有的液晶相位調制器都是利用向列型液晶達到相位調制的功能，但向列型液晶在進行相位調制時會有特定偏振入射的問題。因此在材料改善的方面選用藍相液晶，此材料同時具備了偏振獨立與高速反應時間等特性，但一般藍相液晶的驅動電壓過大，而現有的驅動器系統限制了電壓的上限。所以我們探討不同的藍相液晶比例、高分子單體的比例、光聚合溫度和光聚合強度，降低其驅動電壓，製作出最佳化之聚合物穩固型藍相液晶空間光調制器。最後，我們利用聚合物穩固型藍相液晶空間光調制器，製作相位光柵，而產生繞射效果，量測其一階繞射之效率、反應時間與偏振相關性，驗證此元件與偏振無關且具有快速的反應時間。
本研究的後半段利用SLM高解析度的動態調制能力，調制出各種變化的光渦旋光束。光渦旋(optical vortex)是一種帶有螺旋波前的光束，且具有軌道角動量(orbital angular momentum)，利用SLM對於高斯光束(Gaussian beam)進行調控，改變空間中不同的相位變化，可以得到各種不同的光渦旋場型。利用干涉儀觀察其相位變化，證明具有將高斯光束轉換成光渦旋光束的功能。利用光渦旋的軌道角動量可以疊加的特性，調制出複合式的光渦旋光束，並設計出編碼與解碼的概念。

Spatial light modulator (SLM) is an electro-optic device possessing high spatial resolution of birefringent pixels. Each pixel can be controlled individually by the signals sent from the computer. Therefore, SLM is capable of modulating the spatial distribution of phase, amplitude and polarization of the incident beam, leading to plenty applications in optics and photonics, such as micro-projection and optical tweezers.
This study aims to improve SLM particularly for the use in phase modulation and explore their possible applications in spatial control of optical field. Most of the liquid-crystal-on-silicon (LCoS) based SLMs utilize nematic liquid crystals as their host media. Nematic liquid crystals nevertheless possess intrinsic restrictions including polarization-dependent modulation and slow electro-optic response. Polymer-stabilized blue phase (PSBP) liquid crystals emerge as a promising candidate for SLM because of their optical isotropy and sub-millisecond switching. However, the required operating voltage of current commercially available PSBP materials is still too high for SLMs. In this work, we optimized the recipe and polymerization conditions of PSBP and finally demonstrated diffraction experiments using the phase grating generated by a PSBP-based SLM. The experimental findings revealed polarization-independent and ultrafast phase modulation.
The latter part of the thesis describes simultaneous investigations on complex optical vortices generation exploiting the ability of SLM in spatial phase modulation. An optical vortex is a beam carrying an orbital angular momentum and so exhibiting helical wavefront. Using a high-resolution SLM, we were able to convert a Gaussian beam to a vortex beam carrying various orbital angular momenta. Interferometric measurements were applied to verify the vortex nature of the generated beams. In such vortex beams, different orbital angular momenta interfere with each other, thereby forming complex spatial intensity distribution. This makes SLM a more powerful technique in spatial shaping of light fields. The experimental findings agree well with the simulation results. We also demonstrate signal processing of the vortex beams with the SLM acting as both coding and decoding tools. It is believed that further development of the host PSBP materials and complex optical vortices will lead SLMs to a much wider range of practical applications in both the industries and academics.

論文審定書 i
摘要 ii
Abstract iii
圖錄 viii
表錄 xi
緒論 1
第一章 液晶簡介 2
1-1液晶的發現 2
1-2何謂液晶 2
1-3液晶的物理特性 3
1-3.1秩序參數 3
1-3.2折射率異向性 4
1-3.3介電常數異向性 6
1-3.4連續彈性體理論 8
1-3.5黏滯係數異向性 9
1-4 液晶分類 10
1-4.1向列型 11
1-4.2層列型 11
1-4.3膽固醇型 12
第二章 藍相液晶簡介 14
2-1 藍相液晶的發現 14
2-2 藍相液晶的結構 15
2-3 藍相液晶的光學特性 17
2-4 聚合物穩固型藍相液晶(Polymer-stabilized blue phase) 18
2-5 藍相液晶之電場引致的克爾效應(Kerr effect) 19
第三章 相關理論介紹 22
3-1 空間光調制器簡介與理論介紹 22
3-1.1空間光調制器(Spatial Light Modulator ; SLM) 22
3-1.2相位調制原理 24
3-2 光柵的分類和特性 25
3-3 麥克森干涉(Michelson Interference) 28
3-4 光渦旋(Optical Vortex) 30
3-5 光渦旋模擬相關理論 32
第四章 實驗方法與過程 33
4-1 材料介紹 35
4-2 樣品製作流程 38
4-2.1藍相液晶藥品配製 38
4-2.2聚合物穩固型藍相液晶樣品製作 40
4-2.3聚合物穩固型藍相液晶LCoS-SLM元件製作 41
4-3 實驗架設 42
4-3.1 PSBP LCoS-SLM相位調制量之量測 42
4-3.2 Vertical Field Switching(VFS)之量測 43
4-3.3 PSBP LCoS-SLM相位光柵之量測 44
4-3.4 Nematic LC LCoS-SLM相位調制量之量測 45
4-3.5 光渦旋產生實驗架設 46
4-3.6 光渦旋干涉儀實驗架設 47
4-3.7 光渦旋之疊加實驗架設 48
第五章 實驗結果與討論 49
5-1 藍相液晶於LCoS-SLM之觀察與分析 49
5-1.1 聚合物穩固型藍相液晶於LCoS-SLM之偏光顯微鏡觀察 49
5-1.2 PSBP LCoS-SLM相位調制量之量測分析 50
5-2 降低藍相液晶驅動電壓之方法與分析 51
5-2.1選擇介電異向性相對較大之液晶材料 51
5-2.2不同高分子單體濃度比例之量測與分析 51
5-2.2在不同溫度下光聚合之量測與分析 53
5-2.3不同光聚合強度之量測與分析 54
5-2.4 觀察整體高分子單體濃度比例占6%與5%之光聚合情形 55
5-2.5 整體高分子單體濃度占7%與6%之量測與分析 57
5-2.6換算正向入射之相位變化量- 58
5-2.7 HTG135200-100材料量測與分析 60
5-3 PSBP LCoS-SLM相位光柵量測與分析 62
5-3.1 一階繞射效率之量測 62
5-3.2 一階繞射反應時間 63
5-3.3 一階繞射之偏振特性量測 63
5-4 Nematic LC LCoS-SLM相位調制量之量測與分析 65
5-5光渦旋之產生與應用 66
5-5.1 以Nematic LC LCoS-SLM產生光渦旋 66
5-5.2 以麥克森干涉儀驗證光渦旋 67
5-5.3 光渦旋之編碼與解碼 68
5-5.4 光場調控 72
第六章 結論與未來展望 74

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