Vanadium dioxide (VO₂) is one of the most promising materials for active metasurfaces due to the insulator-metal transition, urging the development of an etching-free patterning method and realization of multifunctionality in various spectral bands. Here, without etching, photolithography of vanadium metal followed by thermal oxidation achieve all-VO₂ slit array metasurfaces that can be exploited as a multifunctional terahertz (THz) transparent electrode. The metasurfaces retain approximately constant THz transparency over the phase transition while the electrical conductivity of the VO₂ lines changes about a thousand times, and near-infrared (NIR) diffraction is switched selectively. Numerical simulation shows that, during the phase transition, a decrease in THz transmission through the VO₂ lines is compensated for by funneling through the slits, which is especially efficient with a deep subwavelength period. On the contrary, at the NIR range, the optical path difference between the slits and the VO₂ lines is controlled according to the VO₂ phase, enabling switching between constructive and destructive interferences for a specific diffraction order. It is expected that the demonstrated patterning method and multifunctional THz transparency will promote VO₂-based metasurfaces, finding multispectral applications such as THz/NIR hybrid communication.

中文翻译：

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绝缘体金属过渡上热氧化钒超表面的多功能太赫兹透明度

由于绝缘体-金属转变，二氧化钒 (VO ₂ ) 是活性超表面最有前途的材料之一，促使开发免蚀刻图案化方法和实现各种光谱带的多功能性。在这里，在没有蚀刻的情况下，钒金属的光刻和热氧化实现了全 VO ₂狭缝阵列超表面，可以用作多功能太赫兹 (THz) 透明电极。_{超表面在相变期间保持近似恒定的 THz 透明度，而 VO 2}的电导率线变化大约一千次，并且有选择地切换近红外 (NIR) 衍射。数值模拟表明，在相变期间，通过 VO ₂线的太赫兹传输的减少通过狭缝漏斗来补偿，这对于深亚波长周期特别有效。相反，在 NIR 范围内，狭缝和 VO ₂线之间的光程差根据 VO ₂相位进行控制，从而能够在特定衍射级的相长干涉和相消干涉之间切换。预计所展示的图案化方法和多功能太赫兹透明度将促进 VO ₂基于超表面，寻找多光谱应用，例如 THz/NIR 混合通信。