POSTECH's Metasurface Merges Color Printing and Holography

Researchers from POSTECH have unveiled a groundbreaking all-dielectric single-layer metasurface that merges triple-color printing and high-efficiency holography into one ultrathin device. This innovative platform, detailed in a paper published in Light: Advanced Manufacturing, overcomes prior limitations by independently controlling phase and spectral responses. By engineering three distinct meta-atoms—including single and double nanorod designs—the device displays vivid structural colors under white light while reconstructing broadband holographic images under coherent light. The team, led by Prof. Junsuk Rho, achieved conversion efficiencies up to 90% at 640 nm, demonstrating robust performance across the visible spectrum. This dual functionality enables multiple layers of optical information in a compact form, paving the way for advanced anti-counterfeiting, secure authentication, and encrypted data storage.

Traditional metasurfaces often sacrifice one function for another: phase-only meta-holograms lack spectral control, while color-printing metasurfaces do not encode phase information. The POSTECH team circumvented this by using anisotropic nanostructures with Pancharatnam-Berry (PB) phase modulation under circularly polarized light, allowing independent tuning of color (via nanostructure size) and holography (via orientation). Simulations confirmed high efficiency, and experiments showed multicolor patterns that switch to hidden holographic logos under laser illumination. This meta-device represents a significant step toward multifunctional flat optics, offering a compact solution for optical security and information storage.