邊界效應對光誘鐵電性液晶分子重新排列的影響

Abstract

鐵電性液晶的非線性光學研究中，主要偏重在thermal effect和electronic effect所引起的非線性光學現象，但是由reorientation effect 所引起的非線性光學研究卻少有人提及。 本論文的主旨是探討邊界效應對光致垂直排列的鐵電性液晶分子重新排列的影響；並且更進一步討論當電場和光場耦合作用時，不同邊界效應對鐵電性液晶螺旋節距和相圖的影響。根據變分法原理，我們發現當系統平衡時，系統可能具有下列三種的邊界條件：(1)Two Hard Boundary Conditions。(2) Two Natural Boundary Conditions。(3)One Hard and One Natural Boundary Conditions。利用數值方法，我們模擬了在這三種邊界條件下，不同外場的液晶指向矢分佈與探討邊界效應對指向矢分佈或是相圖的影響，並且與陳慶逸博士在98年發表在APL上的BULK理論結果相比較與討論。

We have investigated the boundary effects on fileld ( including the optical and electrical fields ) induced molecular reorientations on ferroelectric liquid crystals (FLCs) by numerical methods. We calculated the director profiles of homeotropically aligned FLC films with three different possible boundary conditions : first is hard boundary on both sides , second is the natural boundary on both sides and the other is one hard and one natural boundary. The comparison of these results with that of the published bulk theory and the experimental data is presented.