Zhou Shaolin, Liu Liang, Deng Qinling, Liao Shaowei, Xue Quan, Chan Mansun
School of Microelectronics, South China University of Technology, Guangzhou 510640, China.
ACCESS-AI Chip Center for Emerging Smart Systems, Hong Kong Science Park, Hong Kong, China.
Materials (Basel). 2023 Feb 28;16(5):2013. doi: 10.3390/ma16052013.
Electromagnetic metasurfaces have been intensively used as ultra-compact and easy-to-integrate platforms for versatile wave manipulations from optical to terahertz (THz) and millimeter wave (MMW) ranges. In this paper, the less investigated effects of the interlayer coupling of multiple metasurfaces cascaded in parallel are intensively exploited and leveraged for scalable broadband spectral regulations. The hybridized resonant modes of cascaded metasurfaces with interlayer couplings are well interpreted and simply modeled by the transmission line lumped equivalent circuits, which are used in return to guide the design of the tunable spectral response. In particular, the interlayer gaps and other parameters of double or triple metasurfaces are deliberately leveraged to tune the inter-couplings for as-required spectral properties, i.e., the bandwidth scaling and central frequency shift. As a proof of concept, the scalable broadband transmissive spectra are demonstrated in the millimeter wave (MMW) range by cascading multilayers of metasurfaces sandwiched together in parallel with low-loss dielectrics (Rogers 3003). Finally, both the numerical and experimental results confirm the effectiveness of our cascaded model of multiple metasurfaces for broadband spectral tuning from a narrow band centered at 50 GHz to a broadened range of 40~55 GHz with ideal side steepness, respectively.
电磁超表面已被广泛用作超紧凑且易于集成的平台，用于从光学到太赫兹（THz）和毫米波（MMW）范围的多功能波操控。在本文中，对多个平行级联超表面的层间耦合的较少研究效应进行了深入探索，并将其用于可扩展的宽带光谱调控。通过传输线集总等效电路对具有层间耦合的级联超表面的混合共振模式进行了很好的解释并进行了简单建模，该等效电路又被用于指导可调谐光谱响应的设计。特别地，有意利用双层或三层超表面的层间间隙和其他参数来调整层间耦合，以获得所需的光谱特性，即带宽缩放和中心频率偏移。作为概念验证，通过将多层超表面与低损耗电介质（罗杰斯3003）平行夹在一起级联，在毫米波（MMW）范围内展示了可扩展的宽带透射光谱。最后，数值和实验结果均证实了我们的多个超表面级联模型对于宽带光谱调谐的有效性，该模型分别实现了从以50 GHz为中心的窄带到40~55 GHz的拓宽范围且具有理想侧边陡度的调谐。
