Terahertz (THz) waves have been widely hailed as a key enabling technology for future sixth generation (6G) wireless networks. Dynamic modulation of their polarization states is of great attraction for high-capacity communications and anisotropic sensing. The development of such technology is, however, still in very early stage owing to the difficulties of realizing electrical reconfigurability for THz devices. Artificially constructed metasurfaces and new nanomaterials, such as graphene, have been shown to provide revolutionary platforms for manipulating and controlling the wave properties, especially at THz frequencies. This work leverages the light–matter interaction in a graphene-integrated metasurface functioning as an electrically reconfigurable THz polarization converter. A novel graphene-gold bilayer topology is applied to construct such a metasurface which enables wide-range electrical tunability of the polarization conversion. Under a y-polarized illumination, the reflected components of x- and y-polarizations are tuned dynamically through an external bias voltage across the metasurface, thereby producing an elliptically polarized wave with tuneable ellipticity and angle. By changing the voltage from 0 V to 12 V, the reflected polarization ellipticity has been tuned from −0.94 to −0.5 at around 240 GHz, featuring linear-to-circular and linear-to-elliptical polarization conversions. Meanwhile, the polarization angle has been modulated from 12° to −23° at around 236 GHz. This work provides an experimentally validated THz graphene-integrated metasurface with wide polarization modulation depths, low biasing voltages and simple configuration. It promises great potential for applications in future THz communications and sensing.

中文翻译：

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用于电可重构偏振转换的太赫兹石墨烯集成超表面

太赫兹 (THz) 波被广泛誉为未来第六代 (6G) 无线网络的关键支持技术。其偏振态的动态调制对于高容量通信和各向异性传感具有巨大的吸引力。然而，由于太赫兹器件实现电气可重构性的困难，这种技术的发展仍处于非常早期的阶段。人工构建的超表面和新型纳米材料（例如石墨烯）已被证明可以为操纵和控制波特性（尤其是在太赫兹频率下）提供革命性的平台。这项工作利用了石墨烯集成超表面中的光与物质相互作用，作为电可重构的太赫兹偏振转换器。采用新颖的石墨烯-金双层拓扑结构来构建这种超表面，该超表面能够实现偏振转换的大范围电可调性。下一个y- 偏振照明，反射分量X- 和y-通过超表面上的外部偏置电压动态调整偏振，从而产生具有可调谐椭圆率和角度的椭圆偏振波。通过将电压从 0 V 更改为 12 V，反射偏振椭圆率在 240 GHz 左右从 -0.94 调整到 -0.5，具有线偏振到圆偏振和线偏振到椭圆偏振的转换。同时，偏振角在236 GHz附近从12°调制到-23°。这项工作提供了一种经过实验验证的太赫兹石墨烯集成超表面，具有宽偏振调制深度、低偏置电压和简单的配置。它在未来太赫兹通信和传感领域具有巨大的应用潜力。