Metamaterials play an important role in the modulation of amplitude and group delay in the terahertz (THz) regime on account of their optical properties, which are rare in natural materials. Here an ultrafast anisotropic switch of the plasmon-induced transparency (PIT) effect is experimentally and numerically demonstrated by metamaterial devices composed of two pairs of planar split-ring resonators and a pair of closed-ring resonators. By integration with a germanium (Ge) film, a recovery time of 3 ps and a decay constant of 785 fs are realized in the metadevice. Stimulated by the exterior optical pump, the PIT windows at different frequencies are switched off with an excellent property of slow light for vertical and horizontal THz polarizations, realizing an astonishing modulation depth as high as 99.06%. This work provides a new platform for ultrafast anisotropic metadevices tunable for amplitude and group delay.

中文翻译：

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锗基超光子器件的超快偏振相关全光开关

由于其光学特性，超材料在太赫兹 (THz) 范围内的振幅和群延迟调制中发挥着重要作用，这在天然材料中是罕见的。在这里，由两对平面裂环谐振器和一对闭环谐振器组成的超材料器件通过实验和数值证明了等离子体诱导透明 (PIT) 效应的超快各向异性开关。通过与锗 (Ge) 薄膜集成，在元器件中实现了 3 ps 的恢复时间和 785 fs 的衰减常数。在外部光泵的激励下，不同频率的 PIT 窗口被关闭，具有优异的垂直和水平太赫兹偏振慢光特性，实现了高达 99.06% 的惊人调制深度。