The use of sub-optical surface features for functional soft-matter devices

下一代液晶器件将用于一系列应用，包括自适应光学（可切换透镜，光束转向器，相位控制器，可切换全息图）和虚拟/增强现实显示器。该项目旨在通过在液晶接触表面上设计亚光学和纳米级特征来探索此类设备的附加功能。这些功能包括多稳定性、光子和等离子体效应。这项工作得到了默克公司和NVD有限公司的支持。最初的测试使用电子束光刻技术在液晶器件的内表面上制造轮廓结构。其目的是为器件增加功能，例如产生稳定的对准状态。该结构需要具有可控闪耀的近正弦形状，但是具有大于1的振幅与节距比。最初的测试成功地制作出了400 nm和300 nm的节距光栅（见图），除了振幅不足以产生双稳态外，它们的形状都是正确的。然而，已经提出了许多增加振幅的新方法，这些方法将成为成功完成该项目的学生的起点。这种结构具有真实的实用目的，因为它们将允许NVD公司生产更高反射率的显示器，并且重要的是允许用于便携式应用的双模LCD / OLED设备。然而，使用二维光子表面结构[1]与液晶相结合，以允许具有其他功能的完全可重构元件，包括光学开关，双稳态和多稳态结构，激光结构和拓扑缺陷之间的相互作用，存在丰富的长期发明的潜力。工业合作伙伴默克公司感兴趣的应用领域是新颖的增强现实显示器。该项目最适合精通某些理论的实验学生。成功的候选人将受益于与包括默克和NVD有限公司在内的工业公司的互动，以及强大的互动工程和在他们最先进的洁净室设施中工作。

The next generation of liquid crystal devices will be used in a range of applications including adaptive optics (switchable lenses, beam steerers, phase controllers, switchable holograms) and Virtual / Augmented Reality displays. This project aims to explore additional functionalities to such devices, through the design of sub-optical and nanoscopic features on the contacting surfaces of the liquid crystal. These functionalities include multi-stability, photonic and plasmonic effects. The work is supported by the industrial companies Merck and NVD Ltd.Initial tests have used electron-beam lithography to fabricate profiled structures on the inner surfaces of liquid crystal devices. The aim is to add functionality to the device, such as producing bistable stable alignment states. The structures need a near sinusoidal shape with controllable blaze, but with an amplitude to pitch ratio of greater than 1. Initial tests succeeded in making 400nm and 300nm pitch gratings (see figure) with the correct shape except but with insufficient amplitudes to produce bistability. However, a number of novel methods for increasing the amplitude have been suggested, and will form the starting point for the successful student working on this project.Such structures have a real practical purpose, since they would allow higher reflectivity displays to be produced by the company NVD, and importantly allow dual mode LCD / OLED devices for portable applications. However, there is potential for a wealth of longer-term invention using 2D photonic surface structures [1] combined with liquid crystals to allow for full reconfigurable elements with other functionalities, including optical switching, bistable and multistable structures, interactions between lasing structures and topological defects. The area of application that interests industrial partner Merck is in novel Augmented Reality Displays.The project is best suited to an experimental student that is proficient with some theory. The successful candidate will benefit from interactions with industrial companies including Merck and NVD Ltd, as well has a strong interaction engineering and working in their state-of-the-art cleanroom facility.