使用光配向技術製作圓對稱液晶偏振調制元件

Axially Symmetric Polarization Modulators Based on photo-aligned Liquid Crystal films

曾穎榆(Ying-Yu Tzeng)

《光學工程》 105期 (2009/04) Pp. 45-50

https://doi.org/10.30011/OE.200904.0007

摘要

本實驗利用光配向技術結合樣品的旋轉使液晶樣品配向成單面或雙面的放射狀與同心圓狀排列，製作方法簡單，僅需一次曝光過程即可完成，且製作過程不用外加電壓或聚合物來固定結構。其中單面光配向達成扭轉放射／同心圓狀液晶結構可用來當作一偏振調制元件，將水平方向的線性偏振光轉換成放射狀或弧對稱狀線性偏振光，此外，我們可以透過改變用來達成光配向用的線性偏振光方位角的不同，得到界於放射狀與同心圓狀間不同漩渦程度排列的液晶配向，進而得到不同漩渦程度的軸對稱線性偏振光，此外，模擬結果與實驗結果也相當符合。
我們進一步透過雙面配向的機制製作出雙面的放射狀與同心圓狀液晶樣品，透過電光特性的量測得知此軸對稱液晶排列結構非常一致且整齊，若將其設計為一個1/2波板，則可以應用作偏振調制元件，入射線性偏振光將被調制為軸對稱線性偏振光出射。

關鍵字

液晶 ； 偏振轉換器

並列摘要

This work demonstrates axially symmetric polarization converters based on photo-alignment in dye-doped liquid crystal (DDLC) films. A linear-shape and linearly polarized beam is applied onto a rotated homogeneous DDLC cell to achieve three axially symmetric polarizations-radial, azimuthal and vortical. Additionally, the spiral degree of the axially symmetric vortical polarization can be controlled by varying the polarization of the pumping light and the simulation results agree well with the experiment.
Furthermore, we also demonstrated two types of the double-side axially symmetric LC structure, radial and azimuthal respectively, base on DDLC film by using double-side photoalignment technique. The axially symmetric structure of the cell is very uniform and simple to fabricate. We also analyze the electro-optical (E-O) characteristic of the cell. In addition, the axially symmetiic structiue devices have potential application for a spatial polarization converter if we design λ/2 axially-symmetric DDLC plate of both radial and azimuthal cell.

並列關鍵字

Liquid crystals ； Polarization-selective devices