Scalable Nanomanufacturing of Metasurfaces Using Nanosphere Photolithography

We report on using Nanosphere Photolithography (NPL) for submicron patterning of Frequency Selective Surfaces (FSS). NPL is a combination of two techniques; colloidal nanolithography — where nanospheres form a self-assembled hexagonal close-packed (HCP) array when dispensed on a surface, and photonic jets — which are created when light is incident onto a microsphere in contact with a surface. NPL creates a mask-free HCP hole array in the photoresist. This pattern can be used with evaporation and lift-off to create an array of antenna elements, constituting the FSS. Alternatively, electrodeposition techniques can be used to deposit the metal elements. The later is particularly appealing as it lends itself to reel-to-reel fabrication techniques. Finally, we demonstrate that geometries other than simple hole arrays can be patterned in the photoresist by exposing the microsphere array with off normal incidence light.