Empowered Layer Effects and Prominent Properties in Few-Layer Metasurfaces

Metamaterials are 3D artificial structures proposed to surpass conventional natural materials and realize novel functions beyond traditional optical elements. Nevertheless, they are usually bulky and difficult to be fabricated. As 2D equivalents of metamaterials, metasurfaces have been proposed to overcome the drawbacks of metamaterials and fully control the polarization, amplitude, phase, and dispersion of electromagnetic waves. Relative to single-layer metasurfaces that have limited controllability and functionality, few-layer metasurfaces have more degrees of freedom and abundant layer effects to design novel devices and achieve high-efficiency applications. This review is focused on the empowered layer effects and prominent properties in few-layer metasurfaces, and some distinctive applications proposed in recent years are discussed. It is expected that few-layer metasurfaces will provide a promising road toward the novel intelligent photonic devices, multifunctional devices, and integrated photonic devices.