Scientists have developed a tiny “rainbow on a chip” that can produce multiple extremely precise high-frequency signals, a technology that could eventually support faster 6G communications, advanced radar and highly accurate quantum timing systems.
Researchers led by Loughborough University created the system using a microchip about the size of a grain of rice.
The chip produces a series of precisely spaced frequencies of light known as a microcomb.
Although invisible to human eyes, the pattern can be imagined as a highly organized rainbow made up of many individual frequencies.
These light frequencies can then be converted into millimeter waves, a type of high-frequency electromagnetic radiation that could play an important role in future wireless technologies.
Millimeter waves are attractive for communications because they provide much more bandwidth, meaning there is more space available for transmitting large amounts of data.
As demand grows for faster connections and higher-resolution content, these frequencies could eventually help increase the capacity of future 6G networks.
Their potential extends beyond smartphones and internet connections. Millimeter waves could also be useful for radar, spectroscopy and astronomical instruments that make highly precise measurements.
However, producing multiple millimeter-wave signals with the stability and accuracy needed for these applications has been difficult.
Microcombs offer a possible solution. They are usually produced by shining laser light into a tiny structure called a microresonator, which traps and circulates the light.
Previous experiments have used microcombs to generate a single precise millimeter-wave frequency. Producing many stable frequencies at the same time could create multiple channels for carrying information.
The Loughborough-led team developed a different design by connecting the chip-based microresonator to a larger loop of optical fiber. Laser light continuously travels through both parts of the system, helping the microcomb form automatically and remain stable.
The researchers say the setup is remarkably resistant to disturbances. Even people jumping up and down next to the laboratory equipment did not disrupt the microcomb.
The team also demonstrated that individual parts of the light “rainbow” could be controlled, making selected frequencies stronger or weaker. This is important because different technologies may require different combinations of signals.
Crucially, the researchers showed that the microcomb’s high precision remained intact when its light frequencies were converted into millimeter waves.
That accuracy could make the technology valuable not only for communications but also for precision timing. Extremely accurate timing is essential for emerging quantum technologies and could improve future navigation and positioning systems.
The technology is still at an early stage. While the central chip is tiny, the complete experimental system currently occupies a tabletop. Researchers believe future versions could become much smaller and more energy-efficient, potentially shrinking to about the size of a shoebox.
The team is also investigating whether the technology could eventually operate on satellites, where reducing size, weight and power consumption is particularly important.
Working with the UK’s National Physical Laboratory and quantum technology researchers, the scientists are now testing how closely their system can approach the extraordinary timing precision of atomic clocks, potentially bringing that accuracy into smaller and more practical devices.
