New type of optical comb source has potential to reduce demand on energy grid
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Researchers at Trinity College Dublin have developed a new light-based technology on a tiny chip that could help make the data centres behind cloud computing, artificial intelligence, and global Internet services faster and more efficient.
In the new research, recently published in leading international journal Nature Communications, the Trinity team reported one such promising advance with collaborators at the University of Bath and the Swiss Federal Institute of Technology Lausanne (EPFL).
The team developed a new way to generate extremely stable signals of light using microscopic ring-shaped devices called ‘microresonators’. These signals form what scientists call optical frequency combs, sometimes described as ‘optical rulers’ because they produce a series of evenly spaced colours of light that can be used to measure light with remarkable precision.
The researchers also demonstrated a new type of light pulse called a ‘hyperparametric soliton’. This stable pulse is the key behind the major advancement in this work, as it allows the comb signals to be produced at different colours of light from the laser that powers the device.
This makes the technology useful for high-speed optical communications that play a major role in data transfer.
The researchers demonstrated this in a wavelength region used for high-speed data links inside large data centres, an area of growing importance as demand for data continues to surge with the expansion of AI computing infrastructure.
Data centres require huge amounts of energy to perform the myriad tasks we ask of them, and those requirements are rapidly increasing – driven, in part, by our ever-growing use of AI. According to the Central Statistics Office, data centres accounted for 22% of total electricity use in 2024, which is more than all urban households (18%) combined. And their electricity use increased by 10% from the previous year.
Prof John Donegan, Professor of Physics at Trinity College Dublin and a funded investigator at the Connect Research Ireland Centre for Future Networks, explained: “We are very excited to have generated a new type of optical source that will be of strong interest to those working in optical communications and high-precision optical measurements. Working with an outstanding optical theorist at the University of Bath and the world-leading microresonator fabrication group in Switzerland, my group has been able to demonstrate a new type of optical comb source.
“Our work also benefits from collaboration with Pilot Photonics, a DCU spin-out developing high-precision laser and comb sources for optical communications. We anticipate that this is just the beginning of this work and that it will develop strongly in the years to come.
“Modern fibre-optic networks send large amounts of data by transmitting many different colours of light through a single optical fibre – a technique known as wavelength-division multiplexing (WDM). But optical frequency combs can generate many of these colours from a single light source, potentially replacing arrays of separate lasers – so by simplifying system design while improving efficiency and stability, comb-based technologies could become important building blocks for future data centre networks and high-capacity internet infrastructure.”
The research was supported by Research Ireland, the UK Engineering and Physical Sciences Research Council, the Conect Centre, the Royal Society and the Leading Innovation and Entrepreneurship Teams of Zhejiang.
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