光為自然界中不可或缺的能源，自古以來一直被廣泛研究其與物質之間交互作用，其中偶氮苯衍生物乃為最常被研究的光響應材料。偶氮苯分子暗態時會處於穩態的棒狀結構(trans態)，經由紫外光照射後，其立體結構變為彎曲狀(cis態)。這種特有的光致異構化反應使偶氮苯分子利於應用在諸多光學/光子學領域，例如將偶氮苯摻雜於液晶薄膜中，藉由其獨特的光致形變反應，可使薄膜體積收縮/膨脹甚至產生彎曲。目前已有相關研究應用於發展仿生動植物、人工瞳孔及機器人手臂等。近年來，基於各向異性液晶聚合物的軟致動器由於其高分辨率、快速切換、靈活可控和抗電磁干擾等優點而引起了人們的極大興趣。作為一個新興領域，液晶聚合物軟致動器在機器人、仿生學和光學應用方面具有巨大的潛力。
本論文製備具有三明治結構之兩種不同配方的膽固醇液晶聚合物薄膜，其中一種是全聚合薄膜，另一種是部分聚合薄膜。實驗上分別量測兩種薄膜之光學、熱性質以及光致薄膜形變特性與雷射輸出方向之間關係。實驗結果發現全聚合薄膜雷射閥值較高，故後續採用部分聚合薄膜來執行光控薄膜形變與調控雷射輸出方向。為達最大雷射輸出效率，雷射樣品採三明治結構製法，外面兩側使用摻雜偶氮苯之膽固醇液晶聚合物薄膜作為布拉格反射鏡，利用偶氮苯光致異構化反應可使偶氮分子立體結構於棒狀(trans態)及彎曲狀(cis態)間轉換，進而拉動整個高分子聚合網絡，巨觀上可觀察到薄膜形變；中間層為增益介質之雷射染料混合高分子。當外在光源激發此三明治結構薄膜時，符合共振模態之雷射會以平行液晶螺旋軸方向輸出。搭配紫外光致形變機制，此三明治結構薄膜會朝光源彎曲，致使雷射輸出方向變化。隨著三明治薄膜彎曲角度越大，雷射輸出角度越大(相較於尚未彎曲時雷射輸出方向)，最大可達57度。

Light is an indispensable energy source in nature, and its interaction with substances has been extensively studied since ancient times. Among them, azobenzene derivatives are the most commonly-studied light-responsive materials. When the azobenzene molecule is in the dark state, it will be in a stable, rod-like structure (trans state). After being irradiated with light (usually ultraviolet light), its 3D structure becomes curved (cis state). If properly matched with other functional materials (such as liquid crystal elastomers, or LCE), this unique photoisomerization reaction would make azobenzene molecules quite useful for many optical/photonics fields. Through the unique light-induced deformation reaction of LCE, the film can be contracted/expanded or even bent. Relevant research has been applied to the development of imitating animals and plants, artificial pupils, and robotic arms. In recent years, soft actuators based on anisotropic liquid crystal elastomers have attracted great interest due to their high resolution, fast switching, flexible controllability, and resistance to electromagnetic interference. As an emerging field, liquid crystal elastomer soft actuators have great potential in robotics, bionics, and optical applications.
In this thesis, photoresponsive cholesteric liquid crystal elastomer (CLCE) films are prepared. To obtain the maximum laser output efficiency, the laser device has a sandwich structure, including two CLCE films cross-linked with azobenzene as two Bragg reflectors, and a laser dye-doped polymer film as a gain medium. The photoisomerization reaction of azobenzene molecules in the CLCE films can switch between the rod-like trans state and the curved cis state, thus pulling the entire polymer network, and the film deformation can be observed macroscopically. When the sandwich-like film is excited by an external light, the laser conforming to the resonance mode will generate in a direction parallel to the helical axis of the CLCE film. With the UV photo-induced deformation mechanism, the sandwich-like film will bend toward the light source, causing the laser emission direction to be tunable. As the bending angle of the sandwich-like film increases, the laser output angle increases (compared to the laser emission direction when the film is not bent), up to 57°.

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