Oxford-based Salience Labs has closed an oversubscribed $125 million Series B funding round to scale its photonic networking chips for AI data center infrastructure. The round was led by Bullhound Capital, whose principal Callum Stewart is joining the company's board. New and returning backers include AMD Ventures, Intel Capital, SBI Group, Hudson River Trading and the British Business Bank, along with existing shareholders Applied Ventures, Oxford Science Enterprises, Cambridge Innovation Capital and Silicon Catalyst Ventures.
The investment is a bet that networking, not raw compute, is becoming the bottleneck inside large AI clusters. As operators link thousands of GPUs across multiple racks, the speed and energy cost of moving data between accelerators increasingly decide how much useful work a facility can deliver. Salience's answer is an all-optical, fully integrated switch architecture built for exactly that scale-up traffic, designed to cut latency and improve performance inside the fabric rather than at its edges.
The company has hardware to point to. It recently demonstrated a live 64-port all-optical photonic switch at ECOC 2026, which it describes as an industry first for silicon photonics optical circuit switching. The new funding is meant to carry that work toward higher-density 128-port and 256-port switches, opening the technology to a wider range of data-intensive and performance-critical environments.
Salience says the money will accelerate deployment of its optical circuit switching technology, expand volume manufacturing, and grow its United States presence in Silicon Valley, where it plans a second West Coast location. Manufacturing scale-up will lean on partners that include Keysight Technologies and Tower Semiconductor, a pairing that matters because photonic devices only change data center economics if they can be produced in volume, not just demonstrated at trade shows.
The market context explains the investor interest. Dell'Oro Group forecasts that cumulative spending on data center switches deployed in AI back-end networks will approach $1 trillion over the next five years, from 2026 through 2030, with scale-up networking projected to account for more than half of that market by 2030. All-optical connectivity is emerging as a leading candidate to relieve the bottlenecks that rising data center demand creates for performance, efficiency, power consumption and cost.
Salience was founded in 2021 and builds on more than a decade of silicon photonics research at the University of Oxford and the University of Münster. It will showcase its switching technology next at the PECC Summit in Sunnyvale, California, on October 20-21.
For enterprise IT and infrastructure teams, the signal is broader than one funding round. Optical circuit switching is moving from research curiosity toward a funded, manufacturable layer of the AI stack, backed by the venture arms of two of the industry's biggest chipmakers. If vendors like Salience can deliver high-port-count optical switches at volume, the design of AI fabrics — and the power budgets behind them — could look very different by the end of the decade.