Dielectric Meta-Atoms with Liquid Crystal Alignment Effect for Electrically Tunable Metasurface

Abstract

Dielectric metasurfaces with tunable functions are increasingly appealing to both the academia and industrial communities. Among the many tuning mechanisms reported so far, metasurface immersed in liquid crystal (LC) stands out as one of the most viable approaches for industrial applications such as Lidar and 3D sensing. However, as with traditional LC devices, alignment processes are necessary for LC-based tunable metasurfaces, leading to additional costs in terms of time and materials. In this paper, we present a novel LC-based tunable metasurface, wherein the alignment of LC is provided by the metasurface structures. LC serves as the dielectric environment for the metasurface with an electrically tunable refractive index. Simultaneously, purposely engineered metasurface induces alignment effects within the LC. The alignment effect of the metasurface on the LC was quantitatively characterized using crossed polarizers. A marked transmission contrast was observed, indicating the high-quality alignment provided solely by the metasurface. Electrical tunability was also measured, recording a maximum modulation depth in transmission amplitude of 94% at near-infrared telecommunication wavelengths. This work highlights the remarkable advantages of LC-based tunable metasurface devices, making them highly valuable for next-generation metasurface-integrated LC on silicon devices.