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Oxford-based Salience Labs closed an oversubscribed $125M Series B led by Bullhound Capital to build all-optical switches that connect thousands of AI GPUs.
Key Takeaways
- Salience Labs raised a $125M Series B on October 14, 2026, led by Bullhound Capital; valuation was not disclosed.
- AMD Ventures, Intel Capital, SBI Group, Hudson River Trading and the British Business Bank joined as new investors.
- The round is roughly four times its $30M Series A, and the company has disclosed no customer deployments.
Lead
Salience Labs, a University of Oxford spinout, announced on October 14, 2026 that it had closed a $125M Series B to scale its photonic optical circuit switches for AI data centers. Bullhound Capital led the oversubscribed round, and its principal Callum Stewart joins the board. The company will use the money to deploy its technology, expand volume manufacturing and open a second West Coast office in Silicon Valley.
Who Backed the Round?
Bullhound Capital led, with AMD Ventures, Intel Capital, SBI Group, Hudson River Trading and the British Business Bank coming in as new investors. Existing backers Applied Ventures, Oxford Science Enterprises, Cambridge Innovation Capital and Silicon Catalyst Ventures also took part. Salience did not disclose a valuation or the split between investors.
The cap table is unusual. AMD and Intel are rivals in processors, and both now hold a stake in a company that sells neutral network plumbing. Hudson River Trading, a quantitative trading firm, is a buyer of low-latency infrastructure as well as an investor.
What Does Salience Labs Actually Build?
Salience builds optical circuit switches that route light between GPUs without converting it to electrical signals and back. Conventional switches perform that conversion at each hop, which adds latency and burns power. An optical circuit switch sets up a direct light path instead, and the company says its design can link thousands of GPUs across multiple racks.
The product line is moving up in port count. A 32-port switch, validated by Keysight Technologies, arrived in spring 2026. A 64-port all-optical silicon photonics switch was demonstrated live at ECOC 2026, which the company calls an industry first for silicon photonics optical circuit switching. The 128-port and 256-port versions are in development, with no timeline given. Tower Semiconductor is a manufacturing partner.
How Does This Round Compare With the Last One?
The Series B is about four times the $30M Series A that closed in early 2025, which Applied Ventures and ICM HPQC Fund led. The seed was $12M in May 2022. Those figures put total disclosed funding at about $167M, though Salience has not published a total.
Pace of capital is the signal here. The company went from a 32-port validation to a 64-port demonstration within months, and investors paid for that progress. What the round does not show is revenue. Salience has disclosed no customer deployments or qualifications, so the $125M is a bet on a roadmap and a manufacturing ramp rather than on shipped volume.
Why Is Optical Switching Drawing This Much Capital?
AI clusters are limited by how fast and efficiently GPUs can exchange data, and power draw in the network is a growing share of that problem. Cignal AI projects the optical circuit switching market will exceed $8 billion by 2030. Dell'Oro Group forecasts about $1 trillion in cumulative data center switch spending from 2026 to 2030, with more than half going to scale-up networks, the tightly coupled links inside a cluster.
Those forecasts are the sector's own framing, and they should be read with caution. Market-size projections for a technology that has barely shipped tend to rest on adoption assumptions that no one has tested. The capital flowing in is real, though.
Who Is Salience Up Against?
Competition is better funded in places. Lumilens has raised more than $700M at a reported $5.51B valuation and is shipping into live hyperscaler data centers. Oriole Networks, another UK photonics company, has raised about $35M and is deployed in the UK's £50M ARIA lab. Salience sits between them on funding and, on disclosed evidence, behind both on deployments.
Its pitch rests on silicon photonics, which lets switches be built on semiconductor fabs' existing processes and fit in a standard 1U box. That route favors manufacturing scale if yields hold. It also puts the company in direct competition with established optical component makers and the in-house switching efforts of large cloud operators.
What Comes Next for Salience Labs?
Near-term milestones are concrete. The company must move from demonstrations to qualified deployments, ship the 128-port and 256-port parts, and show that Tower's fab process can deliver volume. The Silicon Valley expansion puts it closer to the hyperscalers and chipmakers that would decide whether optical circuit switching moves from pilot to purchase order.
Two scenarios are plausible. If a hyperscaler or GPU vendor qualifies the switch in 2027, the strategic investors give Salience a short path to distribution. If qualification slips, a $125M balance sheet buys time but not a position, and better-funded rivals will keep shipping.
Outlook
Salience Labs has the funding, the strategic backers and a working 64-port product. It lacks disclosed customers and a stated valuation. The next 12 months will show whether optical circuit switching becomes standard in AI clusters, and whether an Oxford spinout can hold its place against rivals that already ship to hyperscalers.
