Subwavelength color routers for all-day RGB-NIR sensing with a minimalist-structure metasurface.

Dielectric metasurfaces are promising candidates for high-performance optical systems. Unlike traditional Bayer color filters, metasurface-based spectral routers direct light of different wavelengths to designated pixels, significantly improving energy utilization. We demonstrate a four-channel (RGB-NIR) metasurface router integrating visible and near-infrared spectra. Compared with conventional single-layer structures, each pixel of the proposed router contains only one nanopillar optimized by a genetic algorithm. Experimental results show peak optical transmittances of 31.8%, 39.3%, 41%, and 36.3% at 450 nm, 520 nm, 630 nm, and 760 nm, respectively. With an average optical efficiency of 70%, the device achieves efficient spectral separation and high-quality imaging over 420-800 nm. Therefore, this work provides a design strategy to develop compact and efficient RGB-NIR image-sensing technology.