非對稱式液晶光電元件及其應用;Asymmetrical liquid crystal opto-electronic devices and their applications

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題名:	非對稱式液晶光電元件及其應用;Asymmetrical liquid crystal opto-electronic devices and their applications
作者:	涂清彥;Tu, Ching-Yen
貢獻者:	光電科學與工程學系
關鍵詞:	液晶;光柵;非對稱;liquid crystal;grating;asymmetric
日期:	2019-08-20
上傳時間:	2019-09-03 14:48:21 (UTC+8)
出版者:	國立中央大學
摘要:	本論文分別利用膽固醇液晶搭配四分之一波板與線偏振片、扭轉向列型液晶摻雜二色性染料以及扭轉向列型液晶摻雜二色性染料之光柵探討非對稱光學特性。在膽固醇液晶搭配四分之一波板及線偏振片的實驗中，利用光通過線偏振片與四分之一波板產生可被平面態膽固醇液晶盒反射之旋性偏振光的特性達成非對稱光學特性。由於平面態膽固醇液晶的反射頻譜與入射角有關，因此以1D-DIMOS模擬並分析此液晶裝置之視角限制，此外，也分別討論液晶盒厚度以及外加電場於液晶盒對於此液晶裝置的影響。在摻雜二色性染料的扭轉向列型液晶中，利用扭轉向列型液晶盒之摩擦配向方向相互垂直以及二色性染料的偏振選擇性吸收特性，達成此液晶盒對於線偏振光的非對稱吸收的特性，實驗中測量液晶盒之線偏振旋轉以及偏振選擇性吸收之特性，證實此液晶盒具有非對稱光學特性，並以MATLAB模擬實驗架設作圖與測量結果相互比對。另外，將此液晶結構應用於利用偶氮染料光配向製成的液晶光柵，藉由量測以及MATLAB模擬分析液晶光柵之線偏振旋轉特性，證實當線偏振光入射於照光面與非照光面時，因二色性染料的線偏振光選擇性吸收特性造成的非對稱繞射現象，另分析與討論此液晶盒外加電場產生繞射現象的改變。 ;In this thesis, we report the asymmetrical optical properties of the three liquid crystal (LC) devices, including (i) cholesteric LC coupled with a quarter-wave plate and a linear polarizer, (ii) dichroic dye-doped 90° twisted nematic LC (DDd-90° TNLC), and (iii) dye-doped TNLC gratings. In the first part, the incident light passes through the linear polarizer and the quarter-wave plate to form a circularly polarized light which can be reflected by the planar textures of the cholesteric LC (CLC) plate, so the asymmetrical optical property can be achieved. Moreover, the reflection bandwidth and wavelength of the CLC plate is dependent on the angle of propagation direction of the incident light, so the 1D-DIMOS software was also adopted to simulate the limitation of visual angle of this LC device. In the second part, owing to the rubbing direction of the two glass substrates are perpendicular to each other and the dichroic dyes possess the polarization selective light absorption, the DDd-90° TNLC device has the asymmetrical light absorption property. By measuring the polarization rotation and the polarization selective light absorption, the asymmetrical optical properties of the DDd-90° TNLC are completely demonstrated and analyzed, and the experimental results do agree well with the theoretical analyses. Furthermore, in the final part, we extend such an interesting structure to the dye-doped TNLC grating fabricated through the photoalignment process. According to the experimental results and the theoretical simulation about the polarization rotation properties of the dye-doped TNLC gratings, we demonstrate that the same linearly polarized light (0˚ or 90˚) incident onto the illuminated and the unilluminated surfaces presents the asymmetric diffraction property. Moreover, the diffraction efficiency based on the dichroic dye absorption and phase difference between the two kinds of LC structures of the dye-doped TNLC grating can be tuned electrically.
顯示於類別:	[光電科學研究所] 博碩士論文

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