本論文主要是利用偶氮苯化合物Azo-C5摻雜於膽固醇液晶中，製作出光調變膽固醇液晶光柵並研究其光學特性。
實驗前半部探討在不同表面配向層、電壓大小、樣品厚度和膽固醇液晶螺距關係所形成膽固醇液晶之手紋結構特性，選擇適當條件製作膽固醇液晶光柵並討論其光學性質。
第二部份利用Azo-C5光引致同素異構化反應，摻雜於膽固醇液晶光柵中，使用紫外光照射使光柵週期長度縮小，增加繞射角度，也可照射綠光或增加電壓使光柵週期長度拉長，使得繞射角變小，結合此兩種調控機制，可做連續且大範圍角度的調變。此外並研究照射強紫外光下產生的熱效應對膽固醇光柵影響，熱效應使基板邊界的牽制能力減弱，造成基板附近兩倍週期之Fingerprint轉變為一倍週期Fingerprint之結構。
本實驗製作的膽固醇液晶光柵可應用於Beam-steering且具有低耗能和可快速切換之特性，同時搭配電場及光控可調變480 nm的螺距長度，相當於第二階繞射光偏移7.36°。

This thesis studies the optical properties of one-dimensional photo-tunable grating based on cholesteric liquid crystal (CLC) doped with azobenzene derivative, Azo-C5.
Firstly, the stripe textures of cholesteric fingerprints observed using a polarizing microscope corresponding to the cells with different alignment layers cells, bias voltages, thicknesses to pitch length ratios (d/p) are studied.
In the second part, we investigate the photo-isomerization effect of the azo dye doped in cholesteric gratings. The pitch length of a CLC grating is decreasing with increasing UV irradiation, and thus the diffraction angles become larger. This effect can be reversed with irradiating the sample with a green light or applying a high electric field. Thus, we can steer a beam continuously with a large range of it’s diffraction angle. Moreover, the thermal effect of a cholesteric grating irradiated using a high power UV light is studied. The results show that the diffraction angle decreases with high-power UV irradiation, and that the pitch length of CLCs near the subsrates changes from 2P to P. This is due to the thermo- induced weakness of the surface anchoring .
Based on the obtained results, the use of CLC gratings for beam steering with low consumption and fast switching is feasible. Combined the electric and photo-tunable effects, the pitch length can be tuned a length ~ 480 nm, which corresponds to a angle shift of ~7.36°.

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