Active control of chirality in artificial media such as metamaterials is fundamental in many scientific areas, ranging from research into fundamental optical phenomena to the investigation of novel materials, spectroscopy, and imaging. Precise control of the light polarization states has great importance for light‐matter interaction in chemistry and biology, as media with diverse chiral properties react differently to the incoming polarization of light. In this work an active double layer metamaterial device based on vertically stacked ring resonators is realized by integrating electrostatically tunable graphene as an active element. The device is characterized with a THz time domain spectroscopic system demonstrating an all‐electrical control of circular dichroism and optical activity at ≈2 THz, reporting a tunable ellipticity of 0.55–0.98 and >20° rotation of the plane polarization, respectively, by modifying the conductivity of graphene. Further integration with a narrow frequency quantum cascade laser emitting at ≈1.9 THz, in a crossed polarizer experimental arrangement, realizes an active amplitude modulator, hence highlighting the versatility of this approach. These results represent an important milestone for the investigation of novel concepts in optics and in several applications in the THz range, such as wireless communications and spectroscopy.

中文翻译：

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太赫兹手性超材料调制器

在许多科学领域，从对基本光学现象的研究到对新材料，光谱学和成像的研究，对人工介质（例如超材料）中的手性的主动控制都是至关重要的。精确控制光的偏振态对于化学和生物学中的光-物质相互作用非常重要，因为具有不同手性的介质对入射的光的偏振反应不同。在这项工作中，通过将静电可调石墨烯集成为有源元件，实现了基于垂直堆叠环形谐振器的有源双层超材料器件。该器件的特征在于其THz时域光谱系统证明了在约2 THz的全电子控制圆二色性和光学活性，其椭圆率可调为0.55-0。通过改变石墨烯的电导率，平面极化分别旋转98和> 20°。在交叉偏振器实验装置中，进一步与发射≈1.9THz的窄频量子级联激光器进一步集成，可实现有源幅度调制器，因此突出了该方法的多功能性。这些结果为研究光学和THz范围内的多种应用（例如无线通信和光谱学）中的新颖概念提供了重要的里程碑。