基于二氧化钒超表面相位调制的太赫兹多功能器件

Terahertz multifunctional devices based on vanadium dioxide phase modulation metasurface

摘要:

近年来，太赫兹波调控技术备受关注，开发太赫兹多功能器件以适用不同应用场景至关重要。然而，传统的太赫兹多功能超表面器件仅在单一极化波下进行设计，限制了超表面器件在不同极化操作下的应用潜力。针对这一问题，本文提出利用二氧化钒（VO2）的相变特性，通过调控VO2的温度，设计了一款极化依赖的可调谐太赫兹多功能超表面器件，研究了不同极化操作下所设计超表面器件的功能特性。当太赫兹线极化波入射时，超表面可实现宽/窄带吸收的动态切换：当VO2全部处于金属态时，超表面在3.0-3.3 THz的范围内实现了吸收效率超过90％的高效宽带吸收；当VO2全部处于绝缘态时，超表面则在3.55 THz处实现了吸收效率超过95％的窄带吸收。当太赫兹圆极化波入射时，根据超表面不同单元编码，在频率为0.97 THz处可实现分束、波束偏折、涡旋、分束涡旋、叠加涡旋和聚焦等功能。所设计的超表面具有可调谐多功能的特性，可适用太赫兹领域多种应用场景。

Abstract:

In recent years, terahertz (THz) wave manipulation technology has attracted much attention. It is crucial to develop THz multifunctional devices to adapt to different application scenarios. However, traditional THz multifunctional metadevices are designed only under a single polarization wave, which limits the application potential of metadevices under different polarization operations. In this paper, to address this issue, we propose to utilize the phase transition characteristics of vanadium dioxide (VO2), and design a polarization-dependent tunable THz multifunctional metadevice by regulating the temperature of VO2. The functional characteristics of the designed metadevice under different polarization operations are studied. When THz linearly polarized waves are incident, the metasurface can dynamically switch between wide/narrow band absorption. When VO2 is in the metallic state, the metasurface achieves efficient broadband absorption with the absorption efficiency exceeding 90% in the range of 3.0-3.3 THz. When VO2 is in the insulating state, the metasurface achieves narrowband absorption with the absorption efficiency exceeding 95% at 3.55 THz. When THz circularly polarized waves are incident, beam splitting, beam deflection, vortex, split vortex, superimposed vortex, and focusing functions can be achieved at the frequency of 0.97 THz based on the encoding of different elements on the metasurface. The designed metasurface has tunable and multifunctional characteristics, which can be applied to various application scenarios in the THz field.