本文主要研究將膽固醇型液晶加入光子晶體中，討論其光學特性和應用，並用有限元素法模擬之。由於膽固醇型液晶的結構是一週期性排列的晶體，所以膽固醇型液晶是一個光子晶體，而將此一特別的材料加入光子晶體中，作為缺陷，是本篇論文探討的重點。
　　本篇主要使用有限元素法來模擬光波在膽固醇型液晶中傳遞，藉由改變膽固醇型液晶本身的螺旋距的變化，討論其光子晶體能隙中的變化。再討論以膽固醇型液晶為缺陷材料的光子晶體，其缺陷模態因膽固醇型液晶螺距的改變對於穿透率和群速度的影響，可以設計一個帶通濾波器，並利用在缺陷模態的地方，群速較低，並且因波長不同的變化較小，可以利用在光通訊元件上，能夠有效的減少光訊號失真的現象。

　　In this paper, we have primarily investigated the optical properties and applications of one dimensional photonic crystal ( PC ) with cholesteric liquid crystal by using the finite element method.Because the structure of cholesteric liquid crystal arranges periodically, it can be viewed as a kind of PC. We add this special material into 1D PC as a defect. This is the main part of this paper.
　　In the present study, we use finite element methods to simulate the optical wave propagating in the cholesteric liquid crystal, and discuss the changing of the band gap of the PCs when we change the pitch of the cholesteric liquid crystal. In 1D PCs infiltrated with cholesteric liquid crystal as a defect, we discuss how the pitch affects the transmission ratio and group velocity and design a band pass filter. We can also use the region of defect mode which having the properties of low group velocity and small change of group velocity in different wavelength to design a optical communication device which can reduce the signal distorsion.

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