Intercoupling of Cascaded Metasurfaces for Broadband Spectral Scalability

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 similar to 55 GHz with ideal side steepness, respectively.

Automated summary

This paper investigates the interlayer coupling effects of multiple parallel-cascaded electromagnetic metasurfaces and utilizes them for scalable broadband spectral regulations. The resonant modes of the cascaded metasurfaces with interlayer couplings are modeled by transmission line lumped equivalent circuits, guiding the design of tunable spectral response. The interlayer gaps and other parameters are leveraged to achieve the desired spectral properties, such as bandwidth scaling and central frequency shift. The numerical and experimental results demonstrate the effectiveness of the cascaded model for broadband spectral tuning.