Holey metalens! New metalens focuses light with ultra-deep holes

Metasurfaces are nanoscale structures that interact with light. Today, most metasurfaces use monolith-like nanopillars to focus, shape, and control light. Researchers at Harvard University have developed a metasurface that uses deep and narrow holes, rather than tall nanopillars, to focus light to a single spot. The diameter of these long, thin holes is only a few hundred nanometers, making the aspect ratio – the ratio of the height to width – nearly 30:1. The metalenses were fabricated using conventional semiconductor-industry processes and standard materials, which could allow them to be manufactured at scale in the future.