Single-Layer Bayer Metasurface via Inverse Design

Developing color image sensors with miniaturization and high-resolution as goals brings challenges to conventional color filters that, by absorbing out-of-band light, have low light transmission resulting from light separation. The emergence of nanophotonic color splitters with full-band transmission offers an alternative solution. For the Bayer array imaging sensor, we demonstrate numerically and experimentally a nanophotonic color splitter via introducing an optimization algorithm based on path information in inverse design. The device has a total transmission efficiency of 80% across the entire visible spectrum. It is capable of sorting normal incident red, green, and blue components into their respective target imaging regions with peak efficiencies of up to 58.3%, 52.6%, and 69.6%, respectively, which are significantly higher than that of conventional color filters (similar to 30%). We fabricated the device with a Bayer cell footprint of 1.6 x 1.6 mu m(2) and in experiments obtained its intensity profiles and spectrum properties. The demonstration is an ultracompact Bayer nanophotonic color splitter with a simple single-layer 2D structure.