Pixel-Level Spectral Routers for RGB-IR Sensing

All-dielectric metasurfaces provide an effective way to modulate the amplitude, polarization, and phase of light, promising to achieve enhanced optical functions. Spectral routers based on metasurfaces offer a novel method for significantly improving the energy utilization efficiency of the incident light compared with traditional Bayer filter arrays. Near-infrared light, which can easily offer object details hidden in the dark, is also of great importance in high-quality imaging under low-illumination conditions. To take advantage of both, we employ metasurface-based spectral routers to distribute both visible and near-infrared light into four color channels on the pixel level, whose structure is optimized by an inverse-design optimization algorithm. The average light utilization efficiency is improved to exceed 89% over the modulating region (400–900 nm), and the experimentally fabricated sample proves the color splitting function, potentially advancing RGB-NIR image sensing.