Fig. 1: Physical origins of angular dispersions and schematics of angle-dependent multifunctional meta-devices.
From: Controlling angular dispersions in optical metasurfaces

By controlling the coupling between meta-atoms (upper inset) and the radiation properties of constituent meta-atoms (lower inset), one can realize angle-dependent multifunctional meta-devices with wave-control functionalities that change as the incident angle of the excitation light varies