Facile Nanocasting of Dielectric Metasurfaces with Sub-100 nm Resolution.

This work presents a facile nanocasting technique to fabricate dielectric metasurfaces at low cost and high throughput. A flexible polymer mold is replicated from a master mold, and then the polymer mold is used to shape particle-embedded UV-curable polymer resin. The polymer mold is compatible with flexible and curved substrates. A hard-polydimethylsiloxane improves mechanical stability of the polymer mold providing sub-100 nm patterning resolution. The patterned resin itself can work as a metasurface without secondary operations because dielectric particles sufficiently increase the refractive index of the resin. The absence of the secondary operations allows our method to have higher productivity and cost competitiveness than those of typical nanoimprint lithography. Experimental demonstration verifies the feasibility of our method, and the replicated metasurface exhibits a conversion efficiency of 46% in the visible, which is comparable to metasurfaces based on low-loss dielectrics. Given that conventional dielectric metasurfaces have been fabricated by electron beam lithography at formidable cost due to low throughput, our method will be a promising nanofabrication platform and thereby facilitate commercialization of dielectric metasurfaces.