Modin Alvin, Leheny Robert L, Serra Francesca
Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, USA.
Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, Odense, DK-5230, Denmark.
Adv Mater. 2024 Jun;36(23):e2310083. doi: 10.1002/adma.202310083. Epub 2024 Mar 7.
Liquid crystals offer a dynamic platform for developing advanced photonics and soft actuation systems due to their unique and facile tunability and reconfigurability. Achieving precise spatial patterning of the liquid crystal alignment is critical to developing electro-optical devices, programmable origami, directed colloidal assembly, and controlling active matter. Here, a simple method is demonstrated to achieve continuous 3D control of the directions of liquid crystal mesogens using a two-step photo-exposure process. In the first step, polarized light sets the orientation in the plane of confining substrates; the second step uses unpolarized light of a prescribed dose to set the out-of-plane orientation. The method enables smoothly varying orientational patterns with sub-micrometer precision. As a demonstration, the setup is used to create gradient-index lenses with parabolic refractive index profiles that remain stable without external electric fields. The lenses' focal length and sensitivity to light polarization are characterized through experimental and numerical methods. The findings pave the way for developing next-generation photonic devices and actuated materials, with potential applications in molecular self-assembly, re-configurable optics, and responsive matter.
由于液晶具有独特且易于调节的特性和可重构性，它们为开发先进的光子学和软驱动系统提供了一个动态平台。实现液晶取向的精确空间图案化对于开发电光器件、可编程折纸、定向胶体组装以及控制活性物质至关重要。在此，展示了一种简单的方法，通过两步光曝光过程实现对液晶分子取向方向的连续三维控制。第一步，偏振光在限制基板平面内设定取向；第二步，使用规定剂量的非偏振光设定平面外取向。该方法能够以亚微米精度实现平滑变化的取向图案。作为演示，该装置用于创建具有抛物线折射率分布的梯度折射率透镜，这些透镜在没有外部电场的情况下保持稳定。通过实验和数值方法对透镜的焦距和对光偏振的灵敏度进行了表征。这些发现为开发下一代光子器件和驱动材料铺平了道路，在分子自组装、可重构光学和响应性物质方面具有潜在应用。
