流動引致分子排列之液晶繞射光柵

Abstract

液晶相位光柵具有分光、可調變特性，在光通訊、光譜儀甚至投影顯示系統等領域都被廣為使用，本論文提出一種別於傳統製作液晶光柵的作法，利用向列液晶自然流動時所呈現的物理特性，加上利用可聚合的光反應型液晶材料，達到不用配向層而能使液晶分子具有排列秩序，經光聚合反應後將液晶分子的排列鎖定，進而得到具有光學異向性的聚合物光柵。隨後在光柵中流入可隨電場驅動之液晶材料，即可得到一可調變繞射強度之液晶相位光柵。此種光柵可不受電場邊緣效應的影響，因而可大幅縮小光柵週期，進一步提升其可應用之範疇。

Liquid crystal Diffraction Gratings can be applied for beam splitting and electrically tuning. It was widely used in optical communication, spectrometer and projection display technologies. In this thesis, a novel method different from the traditional fabrication is proposed. We made use of a photo-reactive mesogen and utilized the physic property of free flowing nematic liquid crystal. The molecular orientation without alignment layer was acquired. After photo-polymerization, the order of the orientation was locked. Anisotropic polymer gratings, then, were formed. The LC material that can be driven by electric fields was filled into the polymer grating and then a tunable LCPG was obtained. The Grating is free from the limitation caused by fringing field effect. Therefore, the period of grating can be reduced and the field of application will expand.