With high feature density and subwavelength dimensions, visible
spectrum metalenses are challenging to scalably
manufacture. Electron beam lithography and short-wavelength
photolithography capable of patterning metalenses for the visible
do so at high cost per wafer. Here, we present a low-cost and
scalable fabrication process based on nanoimprint lithography, and
use it to demonstrate metalenses designed for 550 nm light with 4
mm diameter and NA=0.2. Our metalenses are formed of silicon
nitride nanoposts with critical dimensions smaller than 100 nm. In
this presentation we report focusing efficiencies above 50%,
share holographic characterization data, and demonstrate
imaging.
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