Structural influence on the color cone lasing emission in dye-doped cholesteric liquid crystals

• Main Authors: Jia-De Lin, 林嘉德
• Other Authors: Chia-rong Lee
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/41339202948960845230

碩士 === 國立成功大學 === 光電科學與工程研究所 === 97 === Novel color cone lasing emission (CCLE) in the dye-doped cholesteric liquid crystal (DDCLC) was discovered by Lee et. al. very recently. To understand the key to induce such a new lasing action, this thesis focuses on the investigation on the influence of the CLC structure on the optical efficiency (energy threshold and relative slope efficiency) of the CCLE in DDCLC cells. Four different cells with and without surface alignment and treatment of a rapid thermal-pressing processing (RTPP) are fabricated. Some important experimental results are obtained and explained as follows: 1)The optical efficiency of the obtained CCLE increases with increasing the preservation time after completing the preparation of the DDCLC cell with surface alignment and without the treatment of the RTPP (cell A). This is because the number of the oily steak in the multi-domain texture and thus the induced scattering decrease with increasing the preservation time due to the self-adjustment of CLC texture under the anchoring effect of the surface alignment. 2)An optimum efficiency of the CCLE based on cell A can be obtained if the preservation time is increased to 216 hrs. However, based on the cell with surface alignment and the treatment of the RTPP (cell C), the CCLE with a same optimum efficiency as that using cell A can be obtained when the preservation time is reduced to 36 hrs. The RTPP markedly reduce the preservation time needed to obtain an optimum efficiency of CCLE, in which a perfect single-domain planar texture can be correspondingly observed. 3)The optical efficiencies of the CCLE obtained based on the cells without surface alignment and with/without the treatment of the RTPP (cells B and D) are much poor than those based on cells A and C. This is because the fact that, without the anchoring effect of the surface alignment, the cells are always full of unapparent and small focal-conic-like defects; thus no CCLE can be measured due to strong scattering. The optical efficiency of the CCLE can be regarded as a useful referable parameter for the quality of the CLC planar texture.