ABSTRACT
A novel ultra-broadband polarization rotator with advanced angular adjustability is proposed for functional devices such as displays and smart windows. The new solution offers dynamic control of light polarization across a broad range of wavelengths, encompassing the complete visible spectrum, ultraviolet and near-infrared. Moreover, it boasts a smaller footprint, faster response times, and lower dispersion compared to conventional rotators. The findings are remarkable in that they show that as the viewing angle increases, the hybrid alignment takes on a twist-like configuration, with the polarization rotation angle determined by the spatial variation in the twist angle. This intriguing behavior leads to an improved range of angular adjustability, as the effective polarization rotation depth is extended. The improved angular adjustability of reconfigurable smart devices surpasses the limitations of traditional polarization rotators, unlocking new innovative possibilities. For example, the rotator plays a crucial role in display technologies, allowing for effective control of viewing angles and minimizing reflection from disturbing external light. Similarly, in smart windows, it optimizes energy conservation by regulating direct sunlight transmission while ensuring clear visibility in normal conditions. It is believed that the proposed advanced ultra-broadband polarization rotator is a significant step forward in the development of reconfigurable smart devices.
ABSTRACT
Liquid crystals (LCs) technology have a well-established history of applications in visible light, particularly in the display industry. However, with the rapid growth in communication technology, LCs have become a topic of current interest for high-frequency microwave (MW) and millimeter-wave (mmWave) applications due to promising characteristics such as tunability, continuous tuning, low losses, and price compatibility. To improve the performance of future communication technology using LCs, it is not sufficient only with the perspective of radio-frequency (RF) technology. Therefore, it is imperative to understand not only the novel structural designs and optimization of MW engineering but also the perspective of materials engineering when implementing advanced RF devices with maximum performance for next-generation satellite and terrestrial communication. Herein, based on advanced nematic LCs, polymer-modified LCs, dual-frequency LCs, and photo-reactive LCs, this article summarizes and examines the modulation principles and key research directions for the design strategies of LCs for advanced smart RF devices with improved driving performance and novel functionality. Furthermore, the challenges in development of state-of-the-art smart RF devices that use LCs are discussed.