Rice-sized photonic chip generates 'rainbow' of frequencies for 6G and quantum computing

Physicists at Loughborough University (UK) and their international colleagues have demonstrated a photonic microchip that can generate a full spectrum of evenly spaced light frequencies and convert them into high-frequency millimeter-wave signals. The findings were published in Nature Communications.

The device, called a "rainbow-on-a-chip," is based on a microcomb — a tiny microresonator about the size of a grain of rice. Inside, laser light circulates, and a separate external loop of optical fiber helps accumulate and sustain the required states. Instead of outputting a single beam, the chip produces a precisely ordered set of frequencies, which are then transformed into millimeter-wave signals.

The main challenge the team addressed was stability. Earlier microcombs could be disrupted by vibrations — even footsteps nearby. The researchers claim the new system remains fully operational even when someone jumps next to it, without losing its frequency lock.

Potential applications include 6G networks, radar systems, spectroscopy, and ultra-precise time synchronization. A stable source of millimeter waves could also accelerate progress in quantum computing and high-precision measurements, according to the scientists.