A German-American startup pursuing a two-laser strategy for inertial fusion: one beam compresses the fuel, a second fires a burst of protons to ignite it -- a scheme that could slash the laser energy needed for net gain.
Conventional laser fusion, as demonstrated at the National Ignition Facility (NIF) in December 2022, uses a single set of lasers to both compress and heat the fuel capsule. Focused Energy, founded in 2021 and headquartered in both Darmstadt, Germany and Austin, Texas, argues that splitting those two tasks between separate laser systems can dramatically reduce the total energy required. The company's approach -- called proton fast ignition -- uses long-pulse lasers to compress a deuterium-tritium fuel pellet to high density, then fires an ultra-short-pulse laser at a thin foil to generate a beam of fast protons that slam into the compressed core and ignite it. The concept was pioneered by co-founder Markus Roth, a professor of laser and plasma physics at Technische Universität Darmstadt, alongside co-founders Todd Ditmire of the University of Texas at Austin and Thomas Cowan of Helmholtz-Zentrum Dresden-Rossendorf.1
Focused Energy raised a $15 million seed round in 2021 and followed with a $67 million Series A, bringing total disclosed funding to roughly $82 million. The investor roster includes Prime Movers Lab, Breakthrough Energy Ventures, and Porsche Ventures. The company has built experimental partnerships with major laser facilities, including OMEGA EP at the University of Rochester's Laboratory for Laser Energetics and the PHELIX laser at GSI Helmholtzzentrum in Germany. A collaboration with Sandia National Laboratories supports target-physics research. In 2024, the U.S. Department of Energy selected Focused Energy for a milestone-based public-private partnership under the DOE Fusion Milestone Program, further validating its technical roadmap.3
The physics case for proton fast ignition rests on decoupling compression from heating. In NIF's central-hot-spot scheme, the lasers must do both simultaneously, demanding extreme symmetry and enormous energy. In fast ignition, the compression can be less perfect because a separate energy source provides the final thermal kick. Protons are attractive as the ignitor because they deposit their energy in a well-defined layer of the compressed fuel, unlike electrons or photons that can preheat the target or scatter unpredictably. Focused Energy's published simulations suggest that gains of 100 or more are theoretically achievable -- far exceeding NIF's gain of roughly 2.4.4
Proton fast ignition has never been demonstrated at ignition-relevant conditions. The key experimental challenge is generating a sufficiently intense, well-collimated proton beam and delivering it to the compressed core with precise timing -- a synchronization problem measured in picoseconds across meters of beam path. The repetition rate required for a power plant (several shots per second) also demands laser technology that does not yet exist at the required pulse energies. Focused Energy's roadmap envisions a proof-of-ignition experiment followed by a pilot plant, but the timeline depends on laser-technology maturation and target-fabrication advances that remain active areas of research across the inertial fusion community.5