UK's Salience Labs raises $125M to scale all-optical switches for AI data centres

As AI clusters grow to thousands of GPUs, the network linking them has become as much of a constraint as the chips themselves. Salience Labs, a photonics company based in Oxford, England, is betting that light-based switching can ease that bottleneck — and has raised $125 million to prove it at scale.

The round

The oversubscribed Series B, announced on 14 October, was led by Bullhound Capital. New backers include AMD Ventures, Intel Capital, SBI Group, trading firm Hudson River Trading and the British Business Bank. Existing investors Applied Ventures, Oxford Science Enterprises, Cambridge Innovation Capital and Silicon Catalyst Ventures also took part. Callum Stewart of Bullhound Capital joins the board. The company has not disclosed a valuation.

Founded in 2021 and led by CEO and co-founder Vaysh Kewada, Salience builds on more than a decade of silicon photonics research at the University of Oxford and the University of Münster.

What the company builds

Salience develops optical circuit switching (OCS) for AI data centres: an integrated, all-optical architecture intended to connect thousands of GPUs across several racks for so-called scale-up networking. Routing signals as light rather than converting them to electrical form is meant to reduce latency and power draw, the company says.

At the ECOC 2026 optics conference, Salience demonstrated a 64-port all-optical photonic switch, which it presents as an industry first for silicon photonics-based OCS. Versions with 128 and 256 ports are in development.

Use of funds and open questions

The money will go to deploying the technology with customers, expanding high-volume manufacturing with partners Keysight Technologies and Tower Semiconductor, developing next-generation switches and growing the engineering team. Salience also plans a second location in Silicon Valley and entry into further markets.

The company has not named customers or given timelines for commercial deployments, and performance claims have yet to be tested in production clusters. Still, the participation of both AMD and Intel investment arms signals that chipmakers see interconnect as a key front in AI infrastructure — and that European deep-tech firms can compete in it.