Researchers have developed 3D-printed pixel-level color routers made from a low-refractive-index resin to boost light transmission for camera sensors, according to a paper published in Nature Communications. The optical elements offer an alternative to traditional filter arrays by steering light rather than absorbing it.
Standard imaging hardware relies on Bayer color filters placed over complementary metal–oxide–semiconductor sensors. These conventional absorption filters transmit only about 30% of incident white light, causing noise in weak illumination. Color routers overcome this limit by guiding specific spectral components directly to designated photodiodes in the near field. While earlier work focused on high-refractive-index metasurfaces, the study examined low-index materials for their potential to deliver higher transmittance and lower-cost mass production.
The authors produced the structures using an inverse design methodology and two-photon-polymerization 3D printing with IP-L resin, a material with a refractive index of approximately 1.5. Optical simulations showed the routers reaching approximately 87% transmittance across the visible spectrum, while experimental measurements recorded about 70% transmittance. Tests pairing the routers with a monochrome sensor demonstrated shorter exposure times and improved color fidelity.
Cheng-Feng Pan, Hao Wang, and Joel K. W. Yang are listed as inventors on a pending patent application covering the router technology. The research involved investigators from the Singapore University of Technology and Design, the National University of Singapore, Beihang University, the Harbin Institute of Technology, and the Industrial Technology Center of Wakayama Prefecture. The work received backing from the National Research Foundation Singapore and the National Natural Science Foundation of China.
