本論文首次藉由在藍相液晶中摻雜螢光染料以及可光致同素異構化之偶氮液晶，發展一可全光切換之藍相液晶雷射，並研究此染料摻雜藍相液晶雷射在不同光波長照射下之雷射輸出可全光切換特性。此雷射輸出可切換之機制乃當照射紫外光後，偶氮液晶產生trans→cis同素異構化反應，分子形狀由棒狀轉變為彎曲狀，進而擾亂藍相液晶晶格結構，而降低雷射輸出強度與增加雷射能量閥值；當進一步關掉紫外光而照射綠光後，偶氮液晶吸收綠光產生反向的cis→trans back同素異構化反應，分子形狀也由彎曲狀轉變回棒狀，不再擾亂藍相液晶的結構，使藍相液晶晶格結構回復原始有序的狀態，而使雷射輸出強度得以回升與雷射能量閥值得以回復降低。因此，藉由以上所述偶氮液晶之可逆性光引致同素異構化效應可引致全光開關切換之藍相液晶雷射元件。

This thesis develops and investigates for the first time an all-optically switchable laser based on a dye-doped blue phase liquid crystal (DDBPLC) with an azoLC dopant. The mechanisms of the all-optical switchability of the DDBPLC laser are attributed to the disturbance and rearrangement of the BPLC structure due to the trans-cis and cis-trans back isomerizations of the azoLC under the successive irradiations of one UV and one green beams, respectively. The curve cis azoLC may disturb the lattice structure of the BPLC to decrease the lasing emission and thus increase the energy threshold, whereas the rod trans azoLC may rearrange the BPLC lattice structure to increase the lasing emission and thus decrease the energy threshold. Therefore, the all-optically switchable BPLC laser can be obtained via the reversible photoisomerization effect.

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