Metallic metasurface for high efficiency optical phase control in transmission mode.

Existing metasurfaces for high efficiency optical phase control in transmission mode are all based on dielectric materials. Metallic metasurfaces for optical phase control in transmission mode never achieved efficiency above 40%. In this paper, we theoretically demonstrate that metallic metasurface constructed by thick nanoparticles can realize high efficiency (above 85%) phase control in optical wavelength range. We investigated the resonant properties of thick nanoparticle arrays and found that bulk magnetic resonance can be formed by antiparallel dipole electric resonances on thick nanoparticles' sidewalls. In addition, lateral Fabry-Perot (FP) resonance can be generated in the cavity constituted by adjacent thick nanoparticles. Both of the two resonances exhibit high transmission with near-zero reflection. What's more, the lateral FP resonance can be utilized to manipulate transmitted phase with high efficiency by adjusting the length of thick nanoparticles. The method proposed here may induce a series of new metasurfaces based on thick nanoparticles for various applications.