A Polarization-Multiplexed Multifunctional Metalens for Triple-Focus Coplanar Imaging

Metalenses capable of controlling more than two types of polarized light have drawn broad interest recently, as they can bring great flexibility and possibilities to the design of highly integrated polarization imaging devices that are not limited by theoretical efficiency. However, current metalenses for practical applications can only perform imaging with dual-polarization states simultaneously through a single aperture. Herein, a polarization-multiplexed multifunctional metalens enabled with three kinds of phase manipulation is proposed. Specifically, by encoding three groups of specific meta-atoms within a single aperture through spatial multiplexing, a "three-in-one" meta-device acting as a composite metalens can be constructed. Theoretical analysis and calculation simulations validate the performance of the metalens. Under circularly polarized light, the metalens exhibits three nearly diffraction-limited coplanar focal spots with horizontal, vertical, and circular polarization properties, respectively, and has a total focusing efficiency of 60%. This device can be used for triple-polarization imaging in real time, with promising prospects in highly integrated polarization imaging systems.