Nonlocal flat optics: toward the ultimate thickness limits of optics

Nonlocal metasurfaces—metasurfaces with an engineered momentum-dependent (spatially-dispersive) response—represent an emerging direction in the field of flat optics, with applications ranging from optical computing to ultra-compact imaging systems. In this talk, we present our recent efforts on this exciting topic at the frontier of the field of metasurfaces. We broadly discuss how nonlocal designs afford new degrees of freedom that enable functionalities and performance metrics unattainable using local metasurfaces and conventional optical systems. We then present some recent advances on nonlocal metasurfaces for space compression ("spaceplates"), which represent an important step in the quest toward the ultimate thickness limits of optics.