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

含有手性分子的液晶具有纳米尺度周期性的自组织螺旋结构，可以看作是一维光子晶体。本文提出了一种在染料掺杂液晶中的激光作用，这种激光作用是由掺杂的激光染料的输入激发引起的带边效应引起的。在带边激发下，实现了提高激光效率和降低激光阈值的目的。我们还进行了CLC中的态密度（DOS）的理论计算。另一方面，周期结构中的缺陷引起的光子局域化在低阈值激光器和微波导等方面有着潜在的应用前景，可以在透射或发射光谱中观察到缺陷模。基于一维周期螺旋结构的局域形变，提出了一种新的手性液晶缺陷模，并证明了这种缺陷模的存在性。 ...更多信息 探讨了该系统中波长调谐的可能性。特别地，当在螺旋结构中以一定的周期性引入多个缺陷时，发现在PBG中出现局域带。我们还研究了双周期结构中光子的局域化，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中的一个缺陷。在该系统中，除了由于具有缺陷的1-D光子晶体引起的缺陷模峰之外，在透射光谱中的螺旋缺陷的带隙边缘处出现具有高Q值的非常尖锐的缺陷模峰。利用双光子共焦显微光刻技术，我们尝试在手性螺旋体系中制备纳米缺陷结构和基于手性液晶的高阶限制结构。研究了这种纳米调制手性螺旋结构的可调谐缺陷模和激光作用。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