Tunable bilayer dielectric metasurface via stacking magnetic mirrors

TL;DR

This paper presents a tunable bilayer dielectric metasurface made of stacked magnetic mirrors, enabling reversible switching between high reflection and high transmission by adjusting interlayer spacing, with potential applications in optical switching.

Contribution

The work introduces a novel method of stacking magnetic mirrors to achieve tunability in metasurfaces through interlayer coupling control, differing from traditional functional superposition approaches.

Findings

Reversible switching between high reflection and high transmission achieved.

Interlayer spacing controls the coupling strength and optical response.

High transmission robustness against perturbations.

Abstract

Functional tunability, environmental adaptability, and easy fabrication are highly desired properties in metasurfaces. Here we provide a tunable bilayer metasurface composed of two stacked identical dielectric magnetic mirrors, which are excited by the dominant electric dipole and other magnetic multipoles, exhibiting nonlocal electric field enhancement near the interface and high reflection. Differ from the tunability through the direct superposition of two structures with different functionalities, we achieve the reversible conversion between high reflection and high transmission by manipulating the interlayer coupling near the interface between the two magnetic mirrors. The magnetic mirror effect boosts the interlayer coupling when the interlayer spacing is small. Decreasing the interlayer spacing of the bilayer metasurface leads to stronger interlayer coupling and scattering suppression of the meta-atom, which results in high transmission. On the contrary, increasing the spacing leads to weaker interlayer coupling and scattering enhancement, which results in high reflection. The high transmission of the bilayer metasurface has good robustness due to that the meta-atom with interlayer coupling can maintain the scattering suppression against adjacent meta-atom movement and disordered position perturbation. This work provides a straightforward method (i.e. stacking magnetic mirrors) to design tunable metasurface, shed new light on high-performance optical switches applied in communication and sensing.