Three-Channel, Single-Cell Encryption Meta Displays

Pockets of the POSTECH campus are transformed into metaverse-ready spaces. Leveraging lessons learned from the COVID-19 pandemic, POSTECH used metaverse learning to allow students to conduct experiments and receive training the same way they do in a physical classroom. All they need to do is wear a virtual reality (VR) device before entering a lab or visiting a nuclear power plant. To go further, what if the teacher and the students can simultaneously see different content adapted to each other in class?

A POSTECH research team led by Professor Junsuk Rho (Department of Mechanical Engineering and Department of Chemical Engineering) with Ph.D. candidates Joohoon Kim and Junhwa Seong (Department of Mechanical Engineering) developed a three-channel encryption metaverse display.

A multifunctional metasurface used in the display presents different images by manipulating the incident polarization of light, promoting the common use of ultra-compact displays and next-generation anti-counterfeiting devices, which project different images depending on location where you look at them.

A metasurface is a sheet of man-made material with arrays of nanostructures, demonstrating superb light-directing ability. Each nanostructure is smaller than one wavelength, challenging researchers to find a way to store as many datasets in it as possible.

Moreover, the conventional metasurface can only hold one piece of information in a nanostructure, requiring shape or matrix changes to record multiple pieces of information. These changes require complicated design manufacturing processes, resulting in additional inconvenience and cost. There is also a limit to reducing its size.

CPR and φ_PCL are calculated by the GS algorithm. These calculated phases are merged by processing via equation (3). By carefully optimizing the anisotropic meta-nanoresonator, a complete 0–2π phase is achieved by varying its in-plane orientation. Meanwhile, we have computed an intensity profile for a focused near-field Fresnel image, and its orientations are discretized. By carefully selecting the required orientations, the proposed trifunctional metasurface is designed. Credit: Advanced sciences (2022). DOI: 10.1002/advs.202203962″>

To overcome this problem, the research team combined Malus’s Law amplitude modulation and geometric phase manipulation to fabricate single-cell-driven, three-channel encryption meta-displays. These have a simple structure, easy and inexpensive to make, and of very small size (0.5 mm). The researchers managed to print three different logos on the meta-displays

Professor Rho explained: “The study is an achievement that transcends the limitations of the conventional metasurface, which could not control near-field and far-field light at the same time. He added: “Our meta-display can be used to create security devices that generate different images depending on the user’s orientation, or to customize VR/AR displays that show the teacher and student different screen contents in the same class.”

The research was recently published in Advanced sciences.

Provided by Pohang University of Science and Technology (POSTECH)