About the Cover
The figure contains three identical metasurfaces, each illuminated by a localized source producing a diverging vortex beam originating at a different distance. The metasurface in the foreground shows reflection of a single color (orange), indicating that the surface interacts only with this wavelength and specific wavefront; in this case, the reflected beam is a phase conjugated version of the source (a converging vortex beam). The other scenarios simply transmit, with no distortion in either the wavefront or the spectrum. These Fano metasurfaces are both spatially and spectrally selective, resonantly reflecting only specifically tailored waves.