A grain-of-rice 'rainbow on a chip' and a small antenna turn one laser into broadband radio

Physicists at Loughborough University have built a chip about the size of a grain of rice that turns a single laser into a comb of evenly spaced light frequencies, an artificial rainbow in invisible light, and shown that a small antenna can convert each of those frequencies into a millimeter-wave radio signal, the high-frequency band where 6G, radar, spectroscopy, and some astronomical instruments are expected to find room.

The result, published in Nature Communications, comes from Loughborough's Emergent Photonics Research Centre and builds on the team's earlier Project RAINBOW work. A microcomb splits one stable laser into many equally spaced "teeth," each at a slightly different color, precise enough to act as a timing reference or, as the new paper shows, to be fed into an antenna that upconverts them to millimeter waves, the radio region above roughly 30 GHz where today's 5G bands are running out of headroom.

The lead author, Dr. Luke Peters, calls the field "data-hungry" and frames the chip as a building block rather than a product. "These applications are still some way off," he said, noting that real-world systems still have to clear power, packaging, and integration hurdles, a candid limitation the related arXiv preprint also records.

The wider pitch reaches beyond 6G to radar, spectroscopy, quantum timing, and space-based instruments. The next concrete hurdle, integrating the comb and the antenna on a single substrate, is what turns the lab demo into something a system builder can actually use.