强激光与粒子束
2023, 35(11): 111003
1 南京邮电大学 电子与光学工程学院,江苏 南京 210023
2 南京邮电大学 集成电路科学与工程学院,江苏 南京 210023
3 南京邮电大学 射频集成与微组装技术国家地方联合工程实验室,江苏 南京 210023
一维手性软光子晶体胆甾相液晶(CLC)在防伪标签、纳米激光器和传感等领域具有广泛的应用。本文采用多步图案化紫外固化方法并结合清洗-重填工艺,实现了多色的柔性自支撑CLC薄膜反射器件。采用标签打印机打印PET图案作为掩膜版,对可聚合的CLC材料进行紫外固化,得到图案化的柔性自支撑CLC薄膜反射器件。在此基础上,将非固化区域的液晶材料洗去并重新填充不同手性剂含量的CLC,再次图案化紫外曝光,即可实现多色的柔性自支撑CLC薄膜反射器件。研究了不同入射角、弯曲曲率半径和温度对反射器件光学性能的影响。实验结果表明,采用上述方法制备的多色可自支撑反射器件具有良好的柔性,不同曲率半径下的布拉格反射中心波长基本不变。随着温度升高,布拉格反射中心波长红移,且具有良好的线性度。多色的可自支撑柔性薄膜反射器件可拓展CLC在显示、传感、激光防护和微纳光学等领域的进一步应用。
胆甾相液晶 布拉格反射 多色自支撑柔性薄膜 光学器件 cholesteric liquid crystal bragg reflection free standing flexible film optical devices
Author Affiliations
Abstract
Department of Electronic Engineering, School of Electronic Science and Engineering, Xiamen University, Xiamen 361005, China
We demonstrate the dynamic coloration of polymerized cholesteric liquid crystal (PCLC) networks templated by the “wash-out/refill” method in the presence of organic compounds. The reflection colors were modulated by two key approaches, that is, the injection of mutually soluble organic fluids into a microfluidic channel and the diffusion of volatile organic compounds (VOCs). The reversible tuning of reflected colors with central wavelengths between and was achieved by alternative injection of nematic liquid crystal E7 (nav = 1.64) and benzyl alcohol (n = 1.54) using syringe pumps. The fascinating iridescence with reflection centers from to was presented from the volatilization and diffusion of alcohol as a model VOC. Additionally, the flow velocity of fluid and the diffusion time were adjusted to explore the underlying mechanism for the dynamic coloration of cholesteric networks. This work is expected to extend the study of PCLCs as a dynamically tunable optofluidic reflector, visually readable sensor, or compact anti-counterfeit label in response to organic compounds.
cholesteric liquid crystal structural color microfluidics diffusion volatile organic compounds Chinese Optics Letters
2022, 20(9): 091602
1 东北林业大学 生物质材料科学与技术教育部重点实验室, 黑龙江 哈尔滨 150040
2 东北林业大学 理学院, 黑龙江 哈尔滨 150040
以稀土氯化物为原料、油酸和十八烯为溶剂, 采用溶剂热法合成粒径为4.4 nm的β-NaGdF4∶Yb3+,Er3+上转换荧光纳米粒子, 并将其分散于纤维素纳米晶(CNC)的悬浮液中, 随后通过蒸发诱导自组装制备了β-NaGdF4∶Yb3+,Er3+/CNC胆甾型复合膜。采用X射线衍射(XRD)、透射电子显微镜(TEM)、傅里叶红外光谱(FTIR)和荧光光谱等分析手段对制备样品的结构、形貌和性能进行分析。结果表明, 制备的NaGdF4∶Yb3+,Er3+上转换荧光纳米粒子的形貌为球形, 结构为纯六方相, 有良好的分散性, 其分散液在980 nm激光激发下发出肉眼可见的明亮绿光。与纳米纤维素溶液自组装后获得同时具有上转换发光和结构色的β-NaGdF4∶Yb3+,Er3+/CNC胆甾型复合膜, 少量β-NaGdF4∶Yb3+,Er3+的引入不改变纳米纤维素膜的胆甾型液晶结构。此外, 纳米纤维素膜作为一维光子晶体在一定程度上可实现对β-NaGdF4∶Yb3+,Er3+荧光性能的调控, 使其禁带边缘的荧光强度增强2.7倍。
纤维素纳米晶 自组装 胆甾型液晶 上转换荧光 cellulose nanocrystalline self assembly cholesteric liquid crystal upconversion fluorescence