Xcimer in line for more fusion funding

Xcimer Energy, the Denver startup working to develop fusion energy based around a high-energy krypton fluoride (KrF) laser, says it is in line for an additional $30.5 million in US government support - assuming that it hits a series of technical milestones.

The latest US Department of Energy (DOE) funding advances Xcimer into the second budget period of the fusion energy development program. In January 2025 the company was one of eight to receive funding in the first phase of the effort.

CEO Conner Galloway, who in 2022 co-founded the startup with Alexander Valys, commented: “We have moved from proving that the physics works to building the industrial technology that can turn fusion into a commercial energy source.

“This additional milestone funding gives us another powerful mechanism to accelerate that work while keeping the majority of the investment and risk in the private sector. We are building the laser, manufacturing systems and supply chain required to make commercial laser fusion possible.”

Directed energy development with RTX

Aside from the milestone-based DOE support, Xcimer has attracted around $200 million in venture funding, and last month the company announced that major US defense contractor RTX had made a minority investment via its RTX Ventures subsidiary.

That deal will see Xcimer explore ways to integrate and containerize its high-energy lasers within RTX’s directed energy air defense systems - a move that echoes the original development of excimer lasers as part of the Strategic Defense Initiative (aka “Star Wars”) program in the 1980s before low-energy versions found widespread utility in lithography systems for chip production.

“The engineering challenges are remarkably similar across fusion and defense,” wrote Galloway and Valys in a letter posted on the firm’s web site following the RTX agreement.

“Laser efficiency, pulsed power, beam quality, optics, manufacturing and cost all matter to both missions. Roughly 95% of the engineering underlying our energy and defense programs is shared.”

Their thinking is that by developing high-energy excimer lasers for both markets, the startup will be able to use sales revenues from defense applications to accelerate commercial fusion technology and establish industrial supply chains without repeated rounds of major equity funding.

“Our defense work is not a detour from our fusion mission; defense accelerates the industrialization that fusion requires,” the co-founders added.

‘Cost-effective’ megajoule energy

Unlike rival approaches relying on large numbers of solid-state laser beams and expensive optical components, Galloway and Valys claim that Xcimer’s architecture uses more cost-effective sources, durable gas optics, and a two-beamline configuration designed to deliver repeatable bursts of megajoule-scale laser energy.

Cliff Thomas, a leading researcher in inertial confinement fusion from the University of Rochester’s Laboratory for Laser Energetics (LLE), has also just joined the company as its new chief scientist for Xcimer’s fusion program.

If all goes according to plan, the Xcimer team thinks it could be adding commercial fusion to the electrical grid around a decade from now.

In the firm’s release announcing the latest milestone funding  Darío Gil, the DOE’s Under Secretary for Science, said: “America invented laser fusion, and America should lead its commercialization.

“Xcimer is making real progress toward a new generation of laser fusion technology, and this award will help accelerate that work.”