A Phase Transition Oxide/Graphene Interface for Incident-Angle-Agile, Ultrabroadband, and Deep THz Modulation
A Phase Transition Oxide/Graphene Interface for Incident-Angle-Agile, Ultrabroadband, and Deep THz Modulation
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用于入射角捷变、超宽带和深度太赫兹调制的相变氧化物/石墨烯接口
DOI：
10.1002/admi.202001297
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发表时间：
2020
影响因子：
5.4
通讯作者：
Liu Cangli
中科院分区：
文献类型：
--
作者：
Zhu Hongfu;Li Jiang;Du Lianghui;Huang Wanxia;Liu Jingbo;Zhou Jinhao;Chen Yuanfu;Das Sujit;Shi Qiwu;Zhu Liguo;Liu Cangli
尽管已经开发出大量功能材料来动态控制太赫兹（THz）传输，但调制深度、工作带宽或角度捷变特性的限制阻碍了它们在高活性太赫兹器件中的应用。在这里，展示了 2D/3D（石墨烯/相变氧化物 VO2）界面，可以对太赫兹波进行前所未有的高效调制，具有灵活的入射角和超宽带。通过调整堆叠的石墨烯层可以在石墨烯/VO2界面处达到阻抗匹配状态，从而实现最小的太赫兹反射幅度。然后通过VO2的半导体-金属相变可以连续改变界面阻抗，实现太赫兹开关。基于这种机制，该异质结构在0.3-1.5 THz范围内，在入射角为35度、48度和53度时分别表现出93%、94%和96%的巨大太赫兹平均幅度调制。而且，相应的插入损耗仅为-7.4、-4.1和-6.5，远低于目前大多数太赫兹调制。 2D材料和3D相变氧化物薄膜集成产生的这些耦合现象和功能拓宽了先前用于太赫兹波动态控制的材料体系，并将促进先进的太赫兹智能器件的实际应用。
Although plenty of functional materials have been explored to dynamically control the terahertz (THz) transmission, the limits in modulation depth, operation bandwidth, or angle-agile characteristics hinder their applications in highly active THz devices. Here, a 2D/3D (graphene/phase transition oxide VO2) interface is demonstrated for unprecedented high-efficiency modulation of THz waves with incident-angle-agile and ultrabroadband. An impedance matching state can be met at the graphene/VO2 interface by adjusting the stacked graphene layers, which leads to a minimal terahertz reflection amplitude. Then the interfacial impedance can be changed continuously via the semiconductor-metal phase transition of VO2 and achieve a THz switching. Based on this mechanism, this heterostructure demonstrates giant THz average amplitude modulation of 93%, 94%, and 96% in 0.3-1.5 THz at the incident angle of 35 degrees, 48 degrees, and 53 degrees, respectively. Moreover, the corresponding insertion loss is only -7.4, -4.1, and -6.5, which is much lower than most of the present THz modulation. These coupling phenomena and functions arising from the integration of 2D material and 3D phase transition oxide film broaden the previous materials system for dynamic controlling of THz wave, and would promote advanced THz smart devices for practical applications.