TL;DR
Salience Labs, an Oxford photonics company founded in 2021, has raised £94m ($125m) in a Series B led by Bullhound Capital to scale manufacturing of its optical circuit switches for AI data centres. New investors include the British Business Bank, Intel Capital, AMD Ventures, Hudson River Trading and SBI Group. The money will also fund a second West Coast site in the US, which is where most of the customers for rack-scale AI networking sit, so the UK keeps the research and must work to keep the jobs.
The company builds on more than a decade of research at Oxford and at Münster in Germany. Its optical switches are built to link thousands of GPUs spread over many racks with high-speed, very low-latency networking, removing a bottleneck in AI workloads. Bullhound’s Callum Stewart joins the board. Earlier backers stayed in, among them Silicon Catalyst Ventures, Cambridge Innovation Capital, Applied Ventures and Oxford Science Enterprises.
Why optical switching
As AI clusters grow, moving data between chips becomes the constraint. Optical circuit switching routes light directly rather than converting it to electrical signals, and Salience says its switch is a fully integrated on-chip design that scales to high-volume manufacturing. “OCS will play a critical role in AI data centre networking,” said chief executive and co-founder Vaysh Kewada, pointing to the “token economics” that customers rolling out optical links now demand.
The strategic investors explained their interest in similar terms. AMD Ventures’ Patrick Rundell said AI infrastructure “is increasingly being designed at rack scale, where networking has a direct impact on system performance, efficiency and economics”. Intel Capital’s Srini Ananth said photonics is “quickly becoming essential to scaling AI infrastructure” and praised Salience’s “integrated silicon photonics architecture and proprietary optical amplification”.
The UK angle
The round is a reminder that the UK’s AI infrastructure story is not only about who builds data centres but about who supplies the components inside them. The British Business Bank’s participation puts public money behind a domestic supplier to the global GPU build-out, in the same week that Nvidia pledged UK compute for safety research and a developer unveiled a 1GW data centre plan in Norfolk.
Looking forward
In our view the test for UK deep-tech rounds of this size is where volume manufacturing ends up. Salience says the funding will take its manufacturing to volume and grow its US footprint, and both chip investors on the cap table are American. If the switches are made at scale in the UK, the round is an industrial-policy win; if the Oxford base becomes the research arm of a Silicon Valley company, it is a familiar story with a better exit. The second West Coast location is the detail to watch.