A tiny chip that produces a precisely organised "rainbow" of light could help unlock faster, higher-capacity 6G communications and precision timing for quantum technologies, according to a new study published in Nature Communications.
Researchers at Loughborough University 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 millimetre waves.
Millimetre 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 millimetre waves could help provide the capacity to do that," said Dr Luke Peters of Loughborough University's Emergent Photonics Research Centre. "They could ultimately contribute to faster, higher capacity 6G networks, but the potential goes far beyond communications."
The key innovation is the way the team generates its microcomb. Unlike conventional approaches that use only a microresonator on a chip, the Loughborough design combines the chip-based microresonator with a larger loop of optical fibre, creating a system in which 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 Dr Peters. "It's remarkably robust too. We've even had people jumping up and down next to the system and the microcomb remains stable."
The team also demonstrated they could control the microcomb "rainbow", making some frequencies stronger or weaker, and showed that its precision and stability was carried through to the millimetre-wave signals it produced.
The researchers are now exploring how the technology could be taken beyond the laboratory, with potential applications in satellite systems where size, weight, and power are important. They are also testing the system against precision clocks for potential applications in timing, navigation, and positioning.
