This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Loughborough University physicists and an international team have demonstrated that a grain-of-rice-sized microchip can be used to produce a spectrum of precisely spaced frequencies of light, which is then converted into multiple high-frequency electromagnetic signals known as millimeter waves. Millimeter waves are of growing interest for future communications because they offer much more bandwidth—essentially more space for transmitting data—but generating them with the precision and stability needed for advanced technologies remains challenging.
"The world is becoming increasingly data hungry. We want to send and receive more information, faster and in higher resolution, and millimeter waves could help provide the capacity to do that," said Dr. Luke Peters, of Loughborough University's Emergent Photonics Research Center.
"They could ultimately contribute to faster, higher-capacity 6G networks, but the potential goes far beyond communications. These frequencies could also be used in radar systems, as well as spectroscopy and astronomical instruments, helping scientists study materials and make extremely precise measurements of the universe. "These applications are still some way off, and there are challenges to overcome before the technology can be used in real-world systems—but our latest work has tackled a major one." One way to generate millimeter waves is by using a microcomb—a highly precise spectrum of light frequencies, arranged like the colors of a rainbow but invisible to the human eye.
These light frequencies can be converted into millimeter waves using a specialized antenna. Previous studies have used microcombs to generate a single, precise millimeter-wave frequency. Producing many at once could open up multiple channels for sending data simultaneously—but doing so requires an exceptionally clear and stable microcomb.
In a new Nature Communications paper, the Loughborough-led team demonstrated just that. They created a system that produces a stable, high-quality microcomb that can be converted into multiple precisely spaced millimeter-wave frequencies at once. The key is the way the team generates its microcomb.
Microcombs are typically created by shining laser light into a microresonator—a tiny structure on a microchip that traps and circulates light. The Loughborough design works differently by combining the chip-based microresonator with a larger loop of optical fiber, creating a system in which the laser light continually circulates through both. "We've essentially created an incredibly precise and stable 'rainbow on a chip,' where the loop keeps feeding the light back through the chip, allowing these states to build up efficiently, start on their own and remain stable even when the system is disturbed," said Peters.
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