Researchers have made significant strides in wireless communication by creating a programmable metasurface capable of direct microwave-to-optical conversion without the need for direct current (DC) power. This innovation not only facilitates high-speed transmission but also empowers bidirectional communication between different mediums, such as air and water.
The developed metasurface functions by integrating microwave and optical components, enabling seamless cross-media communication—an increasingly important aspect of next-generation connectivity.
Traditionally, microwave-to-optical conversion processes, which bridge electrical and optical domains, have relied on complex systems often requiring cumbersome external power supplies. These methods pose limitations including high costs, elevated power consumption, and increased complexity. The newly proposed metasurface, detailed by Zhang et al. (2025), addresses these challenges by eliminating the necessity of external power sources.
Utilizing subwavelength structures, the metasurface simultaneously interacts with both microwave and optical fields. This design allows it to absorb microwave energy efficiently, converting it directly to optical signals without additional wired input. One of the defining characteristics of this approach is its use of integrated semiconductor components, including Schottky diodes, which drive the laser emission on the metasurface through induced currents.
"Our programmable metasurface provides distinctly different routes to implement free-space microwave-to-optical conversion, offering significant advantages of wireless conversion, simple process, and high flexibility," Zhang stated. This capability paves the way for practical applications, making communication systems more efficient.
Experiments demonstrated the effectiveness of this metasurface, achieving bidirectional real-time data exchange across air-water boundaries—a significant milestone for future wireless networks. The research team established two independent transmission links: one for microwave-to-laser communication (from air to underwater) and the other for laser-to-microwave signals (from underwater to air).
The metasurface supports switching speeds of up to hundreds of kilohertz, showcasing its ability to facilitate fast and efficient conversions. "The entire conversion process is completed fully on the integrated ultrathin metasurface, which is critically important for the development of full-duplex and low-overhead cross-media transmission system," the researchers reported.
With this technology, devices operating underwater can transmit data to the surface and vice versa, enabling seamless integration of sensor networks and data communication channels between different environments. Applications could expand to include marine exploration, environmental monitoring, and even enhanced connectivity for remote underwater operations.
The substantial promise of this programmable metasurface lies not only within telecommunications but also indicates potential advancements within quantum technologies, where efficient microwave-optical conversions could facilitate new methods for encoding and transmitting information.
Looking toward the future, these innovations could be of great significance for the anticipated sixth-generation (6G) communication networks, aiming for seamless connectivity across air, water, and even outer space scenarios. The findings from this research decidedly advance the capabilities within telecommunications, setting the stage for fully-connected global networks.