Photonic Crystals based on 3-D Periodically Structured Liquid Crystal and their Functional Applications

含手性分子的液晶具有自组织的螺旋结构，具有纳米级的周期性，可视为一维光子晶体。我们提出了一种具有带边效应的激光作用于掺杂激光染料的染料掺杂胆甾液晶（CLCs）。我们实现了在带边激发下提高激光效率和降低激光阈值。我们还对CLC的状态密度（DOS）进行了理论计算。在带边激励下，DOS急剧增加。另一方面，由于周期结构的缺陷引起的光子局域化在低阈值激光器和微波导等领域具有潜在的应用前景，可以在透射或发射光谱中观察到缺陷模式。基于一维周期螺旋结构的局部变形，我们提出了一种新型的手性液晶缺陷模式，并进一步证明了该系统中波长调谐的可能性。特别是在螺旋结构中以一定周期引入多个缺陷时，发现PBG中出现局域带。在这种模式下，光子被定位在螺旋结构的每一个缺陷上。我们还研究了双周期结构中的光子局域化，其中螺旋周期结构包含在一维周期多层结构中，并作为一维光子晶体的缺陷。在该系统中，除了一维光子晶体存在缺陷导致的缺陷模峰外，透射谱中螺旋缺陷带隙边缘出现了一个非常尖锐的高q值缺陷模峰。在新缺陷模式的基础上，还观察到增强的激光作用。利用双光子共聚焦显微镜光刻技术，在手性液晶的基础上，制备了手性螺旋体系中的纳米缺陷结构和高阶约束结构。研究了可调缺陷模式和激光对这种纳米调制手性螺旋结构的作用。少

Liquid crystals including chiral molecule have a self-organized helical structure with nano-scaled periodicity, which can be regarded as a one dimensional (1-D) photonic crystal. We proposed a laser action in dye-doped cholesteric liquid crystals (CLCs) with a band-edge effect for an input excitation of the doped laser dye. We achieved increasing a lasing efficiency and decreasing a lasing threshold upon the band-edge excitation. We also performed theoretical calculation of a density of state (DOS) in the CLC. The DOS increased drastically by the band-edge excitation.On the other hand, the photon localization caused by the imperfection in periodic structure has been expected as potential applications such as low threshold lasers and micro waveguides, which can be observed as a defect mode in the transmission or emission spectra. We proposed a new type of defect mode in a chiral liquid crystal on the basis of the local deformation of the 1-D periodic helical structure and demonstrated t … More he possibility of the wavelength tuning in this system. Especially, upon introducing multiple defects at a certain periodicity into the helical structure, it was found that a localized band appears in PBG. In this mode, photon is localized at each defect in the helicoidal structure.We also investigated the photon localization in the double periodic structure, in which the helical periodic structure was contained in the 1-D periodic multilayer structure and acts as a defect in the 1-D photonic crystal. In this system, besides defect mode peaks due to the 1-D photonic crystal having the defect, a very sharp defect mode peak with a high Q-value appears at the edge of the band gap of the helix defect in the transmission spectrum. The enhanced laser action has also been observed on the basis of the new defect mode.Using a two-photon confocal microscope lithograpy technique, we have tried to fabricate nano-defect structure in the chiral helicoidal system and higher-order confinement structure based on the chiral liquid crystals. Tunable defect mode and laser actions on this nano-modulated chiral helix structurre have been demonstrated. Less