Damgaard-Carstensen Christopher, Thomaschewski Martin, Bozhevolnyi Sergey I
Centre for Nano Optics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.
Nanoscale. 2022 Aug 11;14(31):11407-11414. doi: 10.1039/d2nr02979k.
Research in optical metasurfaces has explosively grown in recent years, primarily due to their ability of exercising complete control over the transmitted and reflected fields. Application prospects in many emerging technologies require this control to become dynamic, so that the metasurface response could be tuned with external stimuli. In this work, electrically tunable optical metasurfaces operating in reflection as optical free-space modulators are demonstrated. The intensity modulation is achieved by exploiting the electro-optic Pockels effect and tuning the Fabry-Perot resonance in a 320 nm-thick lithium niobate (LN) film sandwiched between a continuous thick gold film and an array of gold nanostripes, serving also as control electrodes. The proposed compact (<1000 μm) modulators operate in the wavelength range of 900-1000 nm, featuring a maximum intensity modulation depth of ∼20% at the driving voltage of ± 10 V within the bandwidth of 8.0 MHz (with the potential bandwidth of ∼25 GHz). By arranging a 2 × 2 array of individually addressable modulators, space-variant control of light reflection is demonstrated, therefore opening a way towards the realization of inertia-free, ultrafast, and robust spatial light modulators based on tunable LN flat optics components.
近年来，光学超表面的研究呈爆发式增长，这主要归功于其能够对透射场和反射场进行完全控制。许多新兴技术中的应用前景要求这种控制具有动态性，以便超表面响应能够通过外部刺激进行调谐。在这项工作中，展示了作为光学自由空间调制器在反射模式下工作的电可调光学超表面。强度调制是通过利用电光泡克耳斯效应并调谐夹在连续厚金膜和金纳米条纹阵列（也用作控制电极）之间的320 nm厚铌酸锂（LN）薄膜中的法布里-珀罗共振来实现的。所提出的紧凑型（<1000 μm）调制器在900 - 1000 nm波长范围内工作，在8.0 MHz带宽（潜在带宽约为25 GHz）内，在±10 V驱动电压下具有约20%的最大强度调制深度。通过排列一个2×2的可单独寻址调制器阵列，展示了对光反射的空间可变控制，从而为基于可调谐LN平面光学组件实现无惯性、超快且坚固的空间光调制器开辟了道路。
