A Terahertz Chiral Metamaterial Modulator
A Terahertz Chiral Metamaterial Modulator
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DOI：
10.1002/adom.202000581
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发表时间：
2020-08-16
影响因子：
9
通讯作者：
Degl'Innocenti, Riccardo
中科院分区：
文献类型：
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作者：
Kindness, Stephen J.;Almond, Nikita W.;Degl'Innocenti, Riccardo
超材料等人工介质中手性的主动控制是许多科学领域的基础，从基本光学现象的研究到新型材料、光谱学和成像的研究。光偏振态的精确控制对于化学和生物学中的光与物质相互作用非常重要，因为具有不同手性特性的介质对入射光偏振的反应不同。在这项工作中，通过集成静电可调石墨烯作为有源元件，实现了基于垂直堆叠环形谐振器的有源双层超材料器件。该器件的特点是太赫兹时域光谱系统，展示了在大约 2 太赫兹处对圆二色性和旋光性的全电控制，通过改变石墨烯的电导率，分别报告了 0.55-0.98 的可调椭圆率和 >20 度的平面偏振旋转。在交叉偏振器实验布置中，与发射频率约为 1.9 THz 的窄频量子级联激光器进一步集成，实现了有源调幅器，从而突出了该方法的多功能性。这些结果代表了光学新概念以及太赫兹范围内多种应用（例如无线通信和光谱学）研究的一个重要里程碑。
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 approximate to 2 THz, reporting a tunable ellipticity of 0.55-0.98 and >20 degrees rotation of the plane polarization, respectively, by modifying the conductivity of graphene. Further integration with a narrow frequency quantum cascade laser emitting at approximate to 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.