在玻璃平板液晶盒摻染料液晶隨機雷射特性之研究

Characteristics of random lasing behavior from dye-doped liquid crystal in glass cell

蔡幸汝(Hsing-Ru Tsai)

指導教授 ： 林家弘

國立臺北科技大學/電資學院/光電工程系研究所/碩士(2013年)

https://doi.org/10.6841/NTUT.2013.00776

摘要

與傳統雷射比較，利用液晶當作散射介質並摻入染料來製造的隨機雷射，可視為一無鏡雷射。本實驗為了比較散射介質的排列情況對隨機雷射的影響，將摻入染料的液晶灌入三種不同形式的樣品盒，分別為兩邊有刷、一邊有刷與完全無刷的情況下來製造有序、部分有序和無全無序的摻染料液晶樣品。藉由Q-開關摻銣釔鋁石榴石雷射激發後，可從光譜中觀察到隨機共振雷射的行為產生。比較三款樣品的受激輻射光譜，我發現當液晶部分有序的情況所產生的輻射線寬最窄,最寬的情況則是液晶排列完全無序的情況。此外，對有序排列的液晶，當泵激光的入射角變化時，受激輻射光的峰值波長會產生變化。在輸出光的部分，在液晶有序排列的情況下，當輸入光和液晶分子夾角垂直時有最大輸出功率，平行時則為最小；在無序的樣品中，輸出光的強度則與入射光的極化方向無關。觀察輸出雷射光的極化發現當液晶在有序排列情況下，輸出光趨近於線性偏極化光，且輸出光電場的震盪方向與液晶的導軸平行，然而在無序排列的情況，輸出的雷射光為非極化光。對於部分有序的液晶樣品，當泵激光入射在沒有刷的玻璃面時，輸出光的特性近似於線性偏極光，但是當泵激光入射在有刷的玻璃面時，由於輸出面的液晶排列在不同的位置不同，因此在不同位置輸出光的極化方向也會不同。

關鍵字

隨機雷射 ； 液晶 ； 玻璃盒 ； 摻染料相列型液晶

並列摘要

In comparing with traditional laser, random lasers produced by dye doped liquid can be a mirrorless lasing. To investigate the influence of the alignment of scattering material on random laser behavior, dye doped liquid crystals are injected into three different kinds of glass cells, including the rubbing polyimide on two and one plate and without any rubbing on each plate to produce the ordering, disordering and completely disordering alignment of liquid crystal. Comparing with emission spectrum linewidth of three types of cell, the disordering alignment dye-doped liquid crystal (DOA-DDLC) shows the narrowest linewidth and the completely disordering alignment dye-doped liquid crystal (CDOA-DDLC) reveals the broadened linewdith. For the ordering alignment dye doped LC (OA-DDLC), the multiple emission peaks measured from optical spectrum will shift obviously as we horizontally rotate the LC cell. Besides, the output intensity of lasing beam depends on the angle of the pump polarization relative to the director of LC molecular for the OA-DDLC. Maximum output intensity is obtained as input polarization perpendicular to the director of LC and minimum output intensity is obtained as input polarization parallel to the director of LC. For the CDOA-DDLC cell, the value of output intensity does not change apparently as we rotate the input polarization. Besides, the output beams from OA-DDLCs are linear polarized lights whose electric field is parallel to the director of NLC, but the output beam for the CDOA-DDLC is unpolarized light. For the DOA-DDLC, the output beam is near polarized light as pump beam is incident on the un-rubbing polyimide plate. While the pump beam is incident on the rubbing polyimide plate, the polarization of output beam is different at different location due to alignment of assembled LCs.

並列關鍵字

Random laser ； liquid crystal ； glass cells ； dye doping NLC

參考文獻

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