Metasurface With an Absorptive Aperture Border

A metasurface optical device can include an array of pillars 13 on a first-side 11f of a substrate 11 aligned with an aperture 15 of, or proximate to, a blocking-layer 12. The blocking-layer 12 can located on the first-side 11f of the substrate 11, on a second-side 11s of the substrate 11 opposite of the first-side 11f, or both. The blocking-layer 12 can prevent light from transmitting through the device in undesirable locations. The blocking-layer 12 can be opaque to incident light and can include an absorptive-layer. Thus, the blocking-layer 12 can have dual functions-blocking and absorbing light.