POSTECH metasurface combines triple-color printing and holography

Researchers at POSTECH have built a single-layer all-dielectric metasurface that prints three colors under white light and projects holograms under coherent light. The design could support compact optical security, anti-counterfeiting and information-storage devices.

Why it matters: - The device combines two functions that usually compete with each other: structural color printing and holography. - The approach could reduce the size and complexity of optical security, anti-counterfeiting and data-storage systems. - The work points to a path for stacking multiple optical functions into one ultrathin metasurface.

What happened: - Researchers led by Prof. Junsuk Rho at POSTECH reported a dual-functional metasurface in Light: Advanced Manufacturing. - The single-layer all-dielectric design prints three reflective colors under white light. - The same device reconstructs broadband holographic images under coherent light. - The paper is identified by DOI 10.37188/lam.2026.022.

The details: - The metasurface uses three distinct meta-atom designs to control color and holography independently. - Anisotropic nanostructures under circularly polarized light enable Pancharatnam Berry phase modulation. - The meta-atom orientation controls holographic phase without changing the spectral response. - The nanostructure size determines the reflected color. - Single- and double-nanorod designs expand the available color range. - Simulations showed conversion efficiencies up to 90% at a target wavelength of 640 nanometers. - Fabricated devices produced vivid structural colors under white light. - The same fabricated metasurfaces reconstructed holographic images with high efficiency under coherent light. - The holographic performance remained robust across a broad range of visible wavelengths. - The team also built metasurfaces that combined all three meta-atom types in one device. - Those devices displayed multicolor printed patterns and separate holographic images such as logos or text. - The paper says the platform can encode multiple layers of optical information in a single metasurface.

Between the lines: - The core advance is decoupling phase control from spectral control, which has been a key limitation in earlier dual-purpose metasurfaces. - The broadband holography suggests the design is more practical than color-hologram systems that work well only in narrow conditions. - The single-layer format is important because it keeps the device compact while preserving multiple functions.

What's next: - The researchers point to uses in anti-counterfeiting labels, secure authentication, encrypted optical data storage and multifunctional displays. - Further work would likely focus on scaling fabrication and moving toward real-world optical security products. - Funding came from the POSCO–POSTECH–RIST Convergence Research Center, the National Research Foundation of Korea, POSCO Asia Fellowship, the Yuhan Foundation New Ilhan Fellowship, the China Scholarship Council and the InnoCORE program.