Applications of liquid crystal planer optical elements based on photoalignment technology in display and photonic devices

Liquid crystal (LC) planar optical elements (POEs) based on photoalignment technology have emerged as a promising approach to manipulating light in various ways. Owing to the high diffraction efficiency, polarization sensitive, and simple fabrication process, LC POEs have found enormous applications in display and photonic devices. In this review, we analyze the Pancharatnam-Berry (PB) phase, polarization holography and photoalignment mechanism, and present a variety of applications in display and photonic devices including optically rewritable liquid crystal device, LC grating, LC lens, LC near-eye displays, LC encryption and LC robots. Although photoalignment-based LC POEs have greatly promoted the development of optics in academia and engineering, there are still many issues that need to be resolved, such as small field of view, uneven imaging quality, chromatic aberration, etc. Due to the ultrathin nature of LC POEs, they can be seamlessly integrated into modern displays, wearables, and many other systems. This review finally concludes with a summary and perspectives on the challenges and opportunities for the applications of LC POEs. It is believed that the developments introduced here can provide directions for future research, and present potential opportunities to encourage future research in the applications of LC POEs. •The working principles of LC, PB phase and photoalignment are introduced.•Applications of LC POEs in display and photonic devices are presented.•This article briefly sorts out and summarizes the latest results of LC POEs.