本論文乃研究向列相液晶摻雜雷射染料及額外摻雜偶氮染料兩種樣品之可電調控與可全光調控隨機雷射特性。實驗結果發現，藉由外加低於電壓閥值之電壓在雷射染料摻雜液晶樣品上，可有效控制液晶秩序及介電特性之空間擾動降低與增加，以控制液晶散射強度降低與增加，造成隨機雷射強度之可電調控性。另外，使用額外摻雜偶氮染料之樣品，實驗結果發現，在分別增加UV光與綠光照射時間之下，隨機雷射強度會產生下降與回升現象。這是由於在分別照射UV與綠光下，樣品中偶氮染料會分別行trans-cis及cis-trans back isomerization效應，導致分別造成液晶等溫地從向列相相變至isotropic相及從isotropic相回到向列相，這會分別造成液晶之秩序性及介電特性之空間擾動降低與增加，分別造成液晶散射強度下降與增加，最後分別造成隨機雷射強度下降與回升。

This thesis investigates electrically and all-optically controllable random lasers based on laser-dye-doped liquid crystal films without and with addition of azo dye, respectively. Experimental results show that the lasing intensity of the random laser can be significantly controlled electrically below the threshold voltage. This is attributable to the effective changes of the spatial fluctuations of the order and the dielectric property and thus of the scattering strength in the LCs by the variation of the applied voltage below the threshold voltage.
In addition, experimental results present that the lasing intensity of the random laser can be all-optically controlled with two-step exposures of UV and green beams based on a laser-dye-doped LC film with addition of azo dye. The all-optical controllability of the random lasing is attributed to the isothermally nematic(N) → isotropic(I) and I → N phase transitions, respectively, due to the UV-beam-induced trans → cis and green-beam-induced cis → trans back isomerizations of the azo dyes. The isothermally N → I and I → N phase transitions of LCs can cause, respectively, the spatial fluctuations of the order and the dielectric property and thus of the scattering strength in the LCs to decrease and increase, resulting in the decay and rise of the random lasing emission.

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