Microcomb chip generates stable millimeter-wave signals for 6G and quantum timing

Physicists at Loughborough University, working with an international team, have demonstrated a microchip-based system that generates a stable microcomb — a precisely spaced spectrum of light frequencies — and converts it into multiple millimeter-wave signals simultaneously. The research was published in Nature Communications.

Millimeter waves offer far more bandwidth than lower frequencies, making them candidates for future 6G networks, radar, spectroscopy and astronomical instruments. However, generating them with the precision and stability required for advanced applications has remained difficult.

The Loughborough system combines a chip-based microresonator with a loop of optical fiber, allowing laser light to circulate continuously through both components. This design produces a microcomb that starts on its own, builds up efficiently and remains stable even when the apparatus is physically disturbed.

In tests, the microcomb maintained its coherence while researchers jumped next to the tabletop setup. The team also showed they could selectively strengthen or weaken individual frequencies within the comb, providing control over the resulting millimeter-wave signals.

Crucially, the precision and stability of the optical microcomb carried through to the generated millimeter waves, yielding a set of highly controlled, precisely spaced signals. That level of accuracy is also valuable for precision timing, a core requirement for emerging quantum technologies.

The researchers are now working to shrink the current tabletop system toward a shoebox-sized package and are exploring satellite deployment where size, weight and power are constrained. Collaborations with the UK National Physical Laboratory and the Quantum Enabled Position, Navigation and Timing hub are testing the microcomb against precision clocks for timing and navigation applications.

The microchip at the heart of the system is the size of a grain of rice, though the full experimental apparatus remains a laboratory setup. Future work aims to improve compactness and energy efficiency while preserving the demonstrated stability and spectral control.