A research team led by Professor Junsuk Rho at POSTECH (Pohang University of Science and Technology) has developed a secure hologram platform that operates solely based on the wavelength of light and the spacing between metasurface layers. The technology makes hacking and counterfeiting virtually impossible, and is expected to be widely adopted for security cards, anticounterfeiting, and military communications. The paper is published in the journal Advanced Functional Materials.

With a growing number of hacking incidents and data breaches, the limitations of digital security are becoming increasingly evident. No matter how sophisticated an encryption scheme is, as long as it exists as code, it is difficult to completely eliminate the risk of intrusion. Motivated by this challenge, the team proposed a new approach that uses the physical conditions of light itself as a security key.

At the core of this innovation is the “metasurface,” an ultrathin optical device that arranges microscopic structures to control light. By illuminating a metasurface, a holographic image can be reconstructed in free space. However, conventional holograms have typically been limited in that a single device could store only one piece of information.