Photonic computing company Lightmatter has raised $400 million in a Series D funding round, giving the company a $4.4bn valuation and bringing the total amount raised by the company to $850m.

The round was led by new investors advised by T. Rowe Price Associates and saw participation from existing investors, including Fidelity Management & Research Company and Google Ventures.

The new valuation comes less than a year after the company reached unicorn status, achieving a $1.2 billion valuation off the back of a $155 million extended Series C funding round in December 2023.

The Boston-based organization specializes in photonics-enabled technologies. By using light instead of electrical signals for computing, it means Lightmatter’s chips don’t experience the same heat or resistance as traditional chip architectures.

The company currently offers two chips: Envise and Passage, the latter of which is an interconnect that takes arrays of traditional processors and links them up using a programmable on-chip optical network. In a statement, Lightmatter said this latest funding round will allow it to ready its Passage chips for mass deployment in partner data centers.

“We’re not just advancing AI infrastructure—we’re reinventing it,” said Lightmatter co-founder and CEO Nick Harris. “With Passage, the world’s fastest photonic engine, we’re setting a new standard for performance and breaking through the barriers that limit AI computing. This funding accelerates our ability to scale, delivering the supercomputers of tomorrow today.”

As of late 2024, Lightmatter employs approximately 190 workers across three continents. In July, Nvidia’s former VP of investor relations and strategic finance, Simona Jankowski, was appointed CFO of Lightmatter.

Last year, DCD exclusively reported that OpenAI had hired former Lightmatter chip engineering lead and Google TPU head Richard Ho as the head of hardware at the generative artificial intelligence company.