Oxford photonics company Salience Labs has raised £94M ($125M) in an oversubscribed Series B led by Bullhound Capital, whose principal Callum Stewart joins the board.
As AI clusters grow to thousands of GPUs, moving data between them has become as much of a constraint as the compute itself. Most datacentre networks still run on electrical switches, which turn every optical signal into electricity to route it and then back into light. That round trip adds latency, burns power and needs a costly transceiver at every port.
Salience builds optical circuit switches that skip the conversion and set up a path for the light itself. The chips are made in silicon photonics, with optical amplification on the same chip as the switching, which the company says offsets signal loss and makes higher port counts practical. Its OC-32M module is pitched at operators building rack-scale AI systems, connecting GPUs across multiple racks, and Salience claims around 10 nanoseconds of latency and under a watt per port. “OCS will play a critical role in AI datacenter networking,” said CEO Vaysh Kewada, who co-founded the company with CTO Johannes Feldmann.
The round follows a live demonstration of a 64-port all-optical switch at ECOC in Málaga in September, which Salience describes as an industry first for silicon photonics, six months after a 32-port version debuted at OFC. Keysight has validated the platform for AI datacentre use, Tower Semiconductor is its manufacturing partner, and 128-port and 256-port switches are in development. Founded in 2021 as a spinout of the universities of Oxford and Münster, Salience previously raised an $11.5M seed in 2022 and a $30M Series A in February 2025.
AMD Ventures, Intel Capital, SBI Group, Hudson River Trading and the British Business Bank joined the round, alongside existing backers Applied Ventures, Oxford Science Enterprises, Cambridge Innovation Capital and Silicon Catalyst Ventures. The money will go on deploying its switches, scaling volume manufacturing and growing in Silicon Valley, where the company plans to open a second West Coast office.
Sources