Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States.
John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02139, United States.
Nano Lett. 2022 Feb 23;22(4):1703-1709. doi: 10.1021/acs.nanolett.1c04723. Epub 2022 Feb 3.
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 a bar spacing of <λ/1.5. We achieve nearly 2π phase variation with an applied bias not exceeding ±25 V, maintaining a reflection efficiency above 91%. Using full-field simulations, we demonstrate a high-angle (51°) switchable beamsplitter with a diffracted efficiency of 93% and an angle-tunable beamsteerer, spanning 18-31°, 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.
动态可重构超表面有望为许多应用提供紧凑、轻量级的空间光调制，包括激光雷达、增强现实/虚拟现实和可见光通信系统。在这里，我们设计并计算研究了具有电驱动的高质量因子硅上铌酸锂超表面，其组成纳米棒具有独立控制，可实现全相位可调谐性和高效率调谐。自由空间光通过周期性扰动耦合到每个纳米棒中的导模，产生的品质因数超过 30000，同时保持小于λ/1.5 的棒间距。我们实现了近 2π 的相位变化，施加的偏置不超过±25 V，反射效率保持在 91%以上。使用全场模拟，我们演示了一个高角度（51°）可切换分束器，具有 93%的衍射效率和角度可调谐的光束转向器，角度范围为 18-31°，效率高达 86%，所有这些都使用相同的超表面器件。我们的平台为具有宽动态调谐范围的高效波前整形器件提供了基础，能够产生几乎任何传递函数。
