Eli Beamlines’ L4 Aton Laser hits 5 petawatts output

27 Oct 2025

Operating safely at this energy level is key for scaling up and for scientific experiments.

The L4 ATON Kilojoule laser at the Extreme Light Infrastructure’s ELI Beamlines Facility, has achieved a peak power exceeding 5 petawatts (1 petawatt = 10¹⁵W), ELI has reported. “This confirms that the L4 can be operated safely and reliably at this energy level which is key for scaling up to higher power and preparing for scientific experiments,” stated the research facility, which is based in Dolní Břežany, Czech Republic, near Prague.

During a test program in September 2025, the flagship L4 ATON system demonstrated a laser performance of 786 J energy compressed to 154 fs, corresponding to a peak power of 5.1 PW. This currently represents the highest pulse energy achieved worldwide at the multi-petawatt power level.

“This accomplishment is about more than figures,” said Allen Weeks, Director General of ELI ERIC. “It demonstrates the maturity of ELI’s technology and establishing ELI as a world-leading facility that enables scientists to carry out groundbreaking experiments in high-intensity laser research.”

L4 ATON an international effort

The L4 ATON laser system was developed by a consortium of international partners made up of National Energetics (USA), EKSPLA (Lithuania) and the ELI Beamlines Facility team. L4 ATON combines optical parametric chirped pulse amplification (OPCPA) with a kilojoule-class, liquid-cooled glass amplifier, allowing operation at a repetition rate of one shot per minute, an order of magnitude higher than other lasers of comparable energy, says ELI.

Installed in the autumn of 2018, a series of upgrades led by ELI Beamlines’ laser and engineering teams, introduced innovations in amplifier cooling, laser diagnostics, control systems, and adaptive optics, significantly improving beam quality, stability, and reliability which have gradually built in-house expertise in the design, alignment, and operation of high-energy, high-repetition-rate laser systems.

The 18 m-long vacuum compressor system was constructed for the final femtosecond pulse compression. Working in cooperation with Lawrence Livermore National Laboratory, California, USA, new multilayer dielectric diffraction gratings were developed, which are a key innovation enabling operation at extremely high energy densities on optical components.

“This successful campaign has confirmed that we can operate safely and stably at this exceptional energy level,” said Roman Hvězda, Director of the ELI Beamlines Facility. “It is the result of years of work by our experts, who have built unique competences in the construction and operation of petawatt-class lasers.”

Future plans

Since 2021, the L4 ATON laser has been serving scientific experiments within the Plasma Physics Platform (P3). A commissioning campaign in December 2025 will integrate the system with new experimental setups, paving the way for external user experiments beginning in 2027 under the ELI User Program.

With its high stability and ability to repeat experiments at one-minute intervals, L4 ATON opens new possibilities for studies in laser-driven particle acceleration, extreme-state physics, and strong-field quantum electrodynamics, as well as for further progress in laser-driven fusion research.

The ELI team is now analyzing performance data to increase power toward 10 PW in 2026. This next step is intended to expand the facility’s experimental reach even further, solidifying ELI’s position among the leading research facilities for high-intensity laser science.

The development and operation of the L4 ATON laser system are supported by the Ministry of Education, Youth and Sports of the Czech Republic (MEYS) through European Structural and Investment Funds (ESIF), and by ELI ERIC Member States’ funding through long term contributions.

ELI video explainer

The Extreme Light Infrastructure (ELI ERIC) is an advanced high-power laser research infrastructure. As an international user facility ELI ERIC provides researchers with access to “world-class high-power, high-repetition-rate laser systems and enables cutting-edge research in new regimes of high-intensity physics, physical, chemical, materials, and medical sciences,” the research facility states. ELI ERIC is designed to operate as a single multi-site organisation with two complementary facilities specialised in different fields of research with extreme light: ELI Beamlines in Dolní Břežany (Czech Republic) and ELI ALPS in Szeged (Hungary). More in the following video: