High quality factor silicon-on-lithium niobate metasurfaces for electro-optically reconfigurable wavefront shaping

Abstract: Dynamically reconfigurable metasurfaces promise compact and lightweight spatial light modulation for many applications, including LiDAR, AR/VR, and LiFi systems. Here, we design and computationally investigate high quality factor silicon-on-lithium niobate metasurfaces with electrically-driven, independent control of its constituent nanobars for full phase tunability with high tuning efficiency. Free-space light couples to guided modes within each nanobar via periodic perturbations, generating quality factors exceeding 30,000, while maintaining bar spacing <$\lambda$/1.5. We achieve nearly 2$\pi$ phase variation with an applied bias not exceeding $\pm$ 25 V, maintaining reflection efficiency above 91%. Using full-field simulations, we demonstrate a high angle, 51\deg, switchable beamsplitter with a diffracted efficiency of 93%, and an angle-tunable beamsteerer, spanning 18-31\deg, with up to 86% efficiency, all using the same metasurface device. Our platform provides a foundation for highly efficient wavefront shaping devices with a wide dynamic tuning range capable of generating nearly any transfer function.