Efficient and flexible manipulation of electromagnetic waves using metasurfaces has attracted continuous attention in recent years. However, previous studies mainly apply sole resonance effect to accomplish the task. Here, we show that introducing a meta-coupling effect would reveal further physical insights in the electromagnetic wave control. To demonstrate this, a reflection-type coupling system composed by two identical linear resonances in a metal–insulator–metal configuration is theoretically proposed using the coupled-mode theory, whose phase diagram can be well controlled upon the coupling changes. Such intriguing optical property is verified by a double C-shaped resonator in the terahertz regime, where the coupling effect can be tuned by changing their either relative distance or rotation. More importantly, the reflection phase shift around the working frequency can be efficiently engineered without having to change the dimensions of the resonators. Two efficient anomalous metasurface deflectors are designed and experimentally characterized, whose maximum measured efficiency is more than 70%. The proposed controlling strategy further enriches the designing freedoms of metasurfaces and may find broad applications in realizing efficient and tunable functional devices.

中文翻译：

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耦合等离子体系统实现高效波前控制

近年来，使用超颖表面对电磁波进行有效而灵活的处理已引起持续关注。然而，先前的研究主要应用唯一的共振效应来完成任务。在这里，我们表明引入元耦合效应将揭示电磁波控制中的更多物理见解。为了证明这一点，使用耦合模式理论从理论上提出了由金属-绝缘体-金属配置中的两个相同的线性共振组成的反射型耦合系统，其相图可以在耦合变化时很好地控制。太赫兹状态下的双C形谐振器验证了这种引人入胜的光学特性，其中可以通过改变它们的相对距离或旋转来调整耦合效果。更重要的是，无需更改谐振器的尺寸，就可以有效地设计工作频率附近的反射相移。设计并通过实验表征了两个有效的异常表面偏导器，其最大测量效率超过70％。所提出的控制策略进一步丰富了超表面的设计自由度，并可能在实现有效且可调节的功能设备中找到广泛的应用。