Electrically-Driven Zoom Metalens Based on Dynamically Controlling the Phase of Barium Titanate (BTO) Column Antennas

The zoom metalens has been a research hotspot for metasurfaces in recent years. There are currently a variety of zoom methods, including dual metalenses, micro-electromechanical system metalenses, polydimethylsiloxane metalenses and Alvarez metalenses. However, for most metalenses, zooming is achieved by manipulating the relative displacement of two or more metasurfaces. Therefore, these methods seem inadequate when faced with more precise zooming requirements, and the precise control of the phase distribution cannot be achieved. In this paper, we innovatively propose an electrically-driven zoom metalens (EZM) of one-dimensional based on dynamically controlling barium titanate (BaTiO₃, BTO) antennas. Using the electro-optic effect of BTO crystals, we can apply a voltage to change the refractive index of BTO nanopillars (n = 2.4-3.6), thereby accurately controlling the phase distribution of column antennas. The proposed EZM can achieve 5× zoom (f = 10-50 μm), with advantages, such as high-speed optical amplitude modulation, ultra-compactness, flexibility and replicability. It can be applied in fields that require ultra-compact beam focusing, zoom imaging, and microscopic measuring.