Switchable metasurfaces with diversified functionalities have become an emerging research area owing to its potential for realizing integrated and miniature meta-devices. Although great efforts have been devoted in this area, switchable metasurfaces with diversified functionalities still require dealing with formidable challenges. In this paper, a switchable broadband terahertz (THz) metasurface with multiple functionalities is proposed utilizing the phase transition property of vanadium dioxide (VO₂), and it can switch functionalities by changing the state of VO₂ from metal to insulator thermally. The simulation results demonstrate that when VO₂ is in metallic state at the temperature of 400 K, the designed metasurface works as a half wave plane with polarization conversion ratio more than 90% at THz frequency band ranging from 0.66 to 1.44 THz. When VO₂ is in insulating state at the temperature of 300 K, the metasurface can flexibly control the phase of the THz wave. As a proof of concept, several devices with high performance for realizing anomalous reflection, diffuse scattering, vortex beam and beam-focusing are numerically investigated. The proposed metasurface has potential applications in THz imaging, sensing and other intellectual systems for photonics integration.

由于具有实现集成和微型元设备的潜力，具有多样化功能的可切换超表面已成为一个新兴的研究领域。尽管在这方面付出了巨大的努力，但具有多样化功能的可切换超表面仍然需要应对艰巨的挑战。在本文中，利用二氧化钒 (VO ₂ )的相变特性提出了一种具有多种功能的可切换宽带太赫兹 (THz) 超表面，它可以通过将 VO ₂的状态从金属热转变为绝缘体来切换功能。仿真结果表明，当 VO ₂在 400 K 的温度下处于金属状态，设计的超表面作为半波平面工作，在 0.66 至 1.44 THz 的太赫兹频段具有超过 90% 的偏振转换率。当VO ₂在300 K的温度下处于绝缘状态时，超表面可以灵活地控制太赫兹波的相位。作为概念证明，对实现异常反射、漫散射、涡旋光束和光束聚焦的几种高性能器件进行了数值研究。所提出的超表面在太赫兹成像、传感和其他用于光子学集成的智能系统中具有潜在的应用。