基于飞秒激光直写的液晶面外区域定向技术及其应用

随着激光加工技术和液晶取向工艺的发展,一种新型的基于飞秒激光直写的液晶面外区域定向技术问世。基于飞秒多光子光聚合激光直写技术制备出由聚合物条带构成的微结构,将其制成液晶盒,并充入不同种类的液晶,即可实现电光开关、磁光开关、光场调控等功能。每条聚合物条带的侧壁上都分布有表面浮雕光栅结构,使得液晶在聚合物条带通道内的定向成为可能。该技术不仅使不同区域内的液晶实现了物理隔离,还可以使液晶和聚合物实现完全的相分离。该技术快捷简单,在可调谐衍射光栅的实现、特殊光场的产生、光子晶体中的光场调控等方面具有重要的应用价值。

Low threshold random lasing in dye-doped and strongly disordered chiral liquid crystals

Random lasing was experimentally investigated in pyrromethene 597-doped strongly disordered chiral liquid crystals (CLCs) composed of the nematic liquid crystal SLC1717 and the chiral agent CB15. The concentration of the chiral agent tuned the bandgap, and disordered CLC microdomains were achieved by fast quenching of the mixture from the isotropic to the cholesteric phase. Random lasing and band edge lasing were observed synchronously, and their behavior changed with the spectral location of the bandgap. The emission band for band edge lasing shifted with the change of the bandgap, while the emission band for random lasing remained practically constant. The results show that the threshold for random lasing sharply decreases if the CLC selective reflection band overlaps with the fluorescence peak of the dye molecules and if the band edge coincides at the same time with the excitation wavelength.

Electrically tunable generation of vectorial vortex beams with micro-patterned liquid crystal structures

We develop a new method for smooth and continuous space-variant alignment of the liquid crystal medium in micro-patterned structures, which is based on a radial micro-structured pattern of polymeric ribbons exhibiting out-of-plane orientation with respect to the ITO-coated glass plates. Thanks to the broad range of electrical tunability of the optical retardation for the micro-patterned liquid crystal structures, transformation of the fundamental Gaussian beam into different types of specific beams, including generalized cylindrical vector beams, vortex beams, and vectorial vortex beams, is efficiently demonstrated.