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

TL;DR

This paper presents a silicon-on-lithium niobate metasurface capable of high-efficiency, electrically reconfigurable wavefront shaping with high quality factors, enabling dynamic beam steering and splitting for advanced optical applications.

Contribution

It introduces a novel high-Q silicon-on-lithium niobate metasurface with independent nanobar control for full phase tunability and high efficiency, advancing reconfigurable optical device technology.

Findings

Quality factors exceeding 30,000 achieved

Nearly 2π phase variation with low bias voltage

High-efficiency beam steering and splitting demonstrated

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.