Nippon Telegraph and Telephone (NTT) has developed a thin, transparent metasurface device capable of controlling the direction of radio waves simply by being installed on surfaces such as window glass. This innovative technology uses the world’s thinnest liquid crystal layer, measuring approximately 3.5µm, enabling precise manipulation of the direction and convergence of radio waves that pass through it. A transmissive metasurface device is an ultra-thin artificial structure that allows radio waves and light to pass through while controlling how they propagate. NTT has implemented its own unique metasurface design, which supports a wide frequency range from microwaves to sub-terahertz bands. At the same time, it maintains a liquid crystal thickness comparable to that of conventional liquid crystal displays, making it both efficient and practical for large-scale applications
This advancement makes it easier to manufacture large-area metasurface devices. Thanks to the ultra-thin liquid crystal layer, the device also achieves faster response speeds, which will allow it to dynamically control radio waves and even track moving terminals in the future. By installing these devices on windows or similar surfaces, it is expected that indoor radio wave environments will improve significantly, helping expand the coverage of future 6G wireless services. Next-generation 6G communication relies on high-frequency bands such as FR3 and sub-terahertz waves. While these frequencies enable extremely fast data transmission, they also have strong directional properties and struggle to penetrate buildings. As a result, signal dead zones often occur, especially when transitioning from outdoor to indoor environments where radio waves are limited to entering through windows and openings.
Metasurface devices, which are thin and planar structures designed to guide radio waves and light, are seen as a promising solution to this challenge. Traditional liquid crystal-based approaches have been considered suitable for large-scale metasurface production, but their thicker liquid crystal layers have made manufacturing difficult and resulted in slower response times. NTT’s newly developed transmissive metasurface overcomes these limitations with a redesigned structure that works effectively even at high frequencies. By reducing the liquid crystal layer to less than one-tenth the thickness of conventional designs, the company has enabled faster operation and improved scalability, making large-area deployment more feasible.
Transparent metasurface devices can actively change the direction of radio waves, guiding 6G signals into indoor spaces where they would otherwise be weak or unavailable. Their thin and flexible nature allows them to be integrated not only into windows but also into walls, displays, and other surfaces. With the design, including control wiring, already close to practical implementation, this technology represents a significant step toward improving indoor connectivity in the 6G era.
