High-efficiency all-dielectric metalenses for multi-focus with arbitrary polarization

Abstract

Metasurfaces, as novel ultrathin planar optical elements, have become a fascinating avenue to modulate one or more optical characteristics including phase, amplitude, and polarization. Especially in multi-functional applications based on different polarization, the complexity and ponderosity of current systems could be avoided by replacing the original components with metasurfaces. In this report, based on interleaving different nanostructures, a design strategy is proposed to associate the target polarization and independent phase modulation with parameters of nanofins. According to the new strategy, a multi-functional metasurface can be constructed in which each channel has an independent function and polarization. To demonstrate our strategy, several arbitrary polarization multi-focus metalenses are simulated using two to five foci, including linear, circular, and elliptical polarization. Due to independence between the phase and polarization, different functions, such as different vortex phases, are also realized using single metasurface. Furthermore, the intensity ratio among the foci can be modified by modulating the numbers of different nanofins. The proposed meta-devices can improve many practical applications such as polarization imaging, optical communication, and holographic displays.