He Ziqian, Tan Guanjun, Chanda Debashis, Wu Shin-Tson
Opt Express. 2019 Apr 15;27(8):11472-11491. doi: 10.1364/OE.27.011472.
In addition to displays, liquid crystals (LCs) have also found widespread applications in photonic devices, such as adaptive lens, adaptive optics, and sensors, because of their responses to electric field, temperature, and light. As the fabrication technique advances, more sophisticated devices can be designed and created. In this review, we report recent advances of two-photon polymerization-based direct-laser writing enabled LC devices. Firstly, we describe the basic working principle of two-photon polymerization. With this powerful fabrication technique, we can generate anchoring energy by surface morphology to align LC directors on different form factors. To prove this concept, we demonstrate LC alignment on planar, curvilinear surfaces as well as in three-dimensional volumes. Based on the results, we further propose a novel, ultra-broadband, twisted-nematic diffractive waveplate that can potentially be fulfilled by this technique. Next, we briefly discuss the current status of direct-laser writing on LC reactive mesogens and its potential applications. Finally, we present two design challenges: fabrication yield and polymer relaxation/deformation, remaining to be overcome.
除了显示器之外，液晶（LC）由于其对电场、温度和光的响应，还在光子器件中得到了广泛应用，如自适应透镜、自适应光学器件和传感器。随着制造技术的进步，可以设计和制造出更复杂的器件。在本综述中，我们报告了基于双光子聚合的直接激光写入技术在液晶器件方面的最新进展。首先，我们描述双光子聚合的基本工作原理。借助这种强大的制造技术，我们可以通过表面形态产生锚定能量，以在不同形状因子上排列液晶指向矢。为了证明这一概念，我们展示了在平面、曲线表面以及三维空间中的液晶排列。基于这些结果，我们进一步提出了一种新型的、超宽带的扭曲向列型衍射波片，该波片有可能通过这种技术实现。接下来，我们简要讨论在液晶反应性液晶元上进行直接激光写入的现状及其潜在应用。最后，我们提出了两个有待克服的设计挑战：制造良率以及聚合物的松弛/变形。
