本篇論文主要在探討摻雜雷射染料的膽固醇液晶雷射元件，在這個實驗中我們觀察到與以往不同的膽固醇液晶雷射輸出方向而此方向將不再是只有平行螺旋軸的方向，而是具有一個cone角的雷射輸出型式，而在不同的cone角上我們將發現到一個有趣的現象，就是隨著不同的cone角我們將觀察到雷射輸出波長連續的變化。實驗中我們將探討為何在不同的角度上雷射的輸出波長會隨之改變，而我們由觀察各個角度的穿透光譜與螢光光譜變化可知道在各個角度上膽固醇液晶還是可視為一個隨角度(θ)變化的一維光子晶體結構，只是所對應到的等效pitch將會改變。而在接下來的實驗中我們將探討雷射的偏振特性、不同角度的臨界激發能量、不同角度的雷射輸出強度與在剛做好的樣品中為何較不容易觀察到在不同cone角有雷射輸出效果，最後利用這個雷射元件我們將做出一個相當具有價值的角度調變雷射輸出波長元件。

This experiment demonstrates an inherent direction-tunable lasing effect in a dye-doped cholesteric liquid crystal (DDCLC) film. This novel lasing effect with continuous variation of wavelength of laser output was found and is blue-shifted as the detected polar angle increases. The photons propagating in different polar angle (θ) experience an effective pitch of P0．cos(θ) in one-dimensional cholesteric planar structure, where P0 is the original pitch of the CLCs in normal direction. In the reflection photonic band-edges, the photons experience a long dwelling time inside the periodic structure and its spontaneous and stimulated emission is strongly enhanced, generating the lasing effect. This direction-tunable lasing effect has not been observed before, we believe that this is because of the defect in the fabricated CLC cell. If the CLC cell is not perfect and includes many structural defects, the defect scattering of the normal lasing mode will significantly suppress the inherent direction-tunable lasing effect. Besides, the dependences of the polarization property and the pumping threshold energy of the laser output on the polar angle have also investigated.

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