Hybrid high-index composite meta-structures with atomic layer-coated nanoparticle-embedded resin

Abstract Metasurfaces offer great potential to replace conventional optics by enabling multi-functionalities in compact form factors. However, their mass production remains at crossroads, as most materials compatible with scalable fabrication like nanoimprint lithography (NIL) exhibit relatively low refractive indices (~ 2), which limit metasurface performance and necessitate tall, high-aspect-ratio meta-atoms prone to bending and collapsing. To address these bottlenecks, we introduce a hybrid nanoparticle-embedded resin (nano-PER) structure that reduces meta-atom height and aspect ratio. By utilizing TiO 2 nano-PER as the core material with thin TiO 2 coatings, we can implement the optical properties of high refractive index with printable material, achieving a height reduction of over 27% and an aspect ratio reduction of more than 36% compared with conventional hybrid structures using nanoimprint resin. Despite the reduced dimensions, our meta-atoms exhibit high broadband properties, with an average conversion efficiency of over 72% across blue (450 nm), green (532 nm), and red (635 nm) wavelengths. Our design provides robustness in the fabrication process, demonstrated by producing a hyperbolic metalens via NIL and experimentally verifying its optical performance, with an average focusing efficiency of 51.23%. These findings mark an important advancement in scalable, high-performance metasurfaces, paving the way for their practical integration into optical applications.