Phase-only transmissive spatial light modulator based on tunable dielectric metasurface

Rapidly developing augmented reality (AR) and 3D holographic display technologies require spatial light modulators (SLM) with high resolution and viewing angle to be able to satisfy increasing customer demands. Currently available SLMs, as well as their performance, are limited by their large pixel sizes of the order of several micrometres. Further pixel size miniaturization has been stagnant due to the persistent challenge to reduce the inter-pixel crosstalk associated with the liquid crystal (LC) cell thickness, which has to be large enough to accumulate the required 2{\pi} phase difference. Here, we propose a concept of tunable dielectric metasurfaces modulated by a liquid crystal environment, which can provide abrupt phase change and uncouple the phase accumulation from the LC cell thickness, ultimately enabling the pixel size miniaturization. We present a proof-of-concept metasurface-based SLM device, configured to generate active beam steering with >35% efficiency and large beam deflection angle of 11{\deg}, with LC cell thickness of only 1.5 {\mu}m, much smaller than conventional devices. We achieve the pixel size of 1.14 {\mu}m corresponding to the image resolution of 877 lp/mm, which is 30 times larger comparing to the presently available commercial SLM devices. High resolution and viewing angle of the metasurface-based SLMs opens up a new path to the next generation of near-eye AR and 3D holographic display technologies.