An international team of physicists has achieved a significant advance in laser science, demonstrating for the first time a practical route to dramatically boosting the intensity of high-power laser light.
The results, published today in Nature (22 April) could unlock the route towards creating the most intense light ever produced in a laboratory, opening the door to experiments that probe the fundamental laws of physics by directly interacting light with the quantum vacuum.
The work was led by Professor Peter Norreys and Dr Robin Timmis at the University of Oxford, working in close collaboration with Professor Brendan Dromey and Dr Mark Yeung at Queen's University Belfast, and scientists from the Science and Technology Facilities Council's Central Laser Facility (CLF).
Using the Gemini laser at the CLF, the team created extremely bright ultraviolet light through an unusual process. In simple terms, they fired an intense laser at a cloud of charged particles (a plasma), causing it to behave like a rapidly moving mirror.
This can be likened to shining a flashlight at a mirror that is rushing toward you at enormous speed. The reflected light becomes compressed and more energetic - similar to how the pitch of a siren rises as an ambulance speeds past. In this case, the "mirror" is moving so fast that Einstein's theory of relativity comes into play, boosting the light to much higher energies. This effect is known as relativistic harmonic generation.
The team also demonstrated a way to concentrate this light even further, in what they call a Coherent Harmonic Focus. An analogy is using a magnifying glass to focus sunlight into a tiny point so intense it can burn paper. Here, instead of sunlight, many different colours (wavelengths) of laser light are brought together and focused into an extremely small region, creating a huge concentration of energy.
This advance could eventually allow scientists to explore one of the most extreme frontiers of physics: how light and matter interact at the most fundamental level, described by a theory called quantum electrodynamics (QED).
Until now, experiments in this area have required smashing high-energy particle beams into powerful lasers and then carefully translating the results between different perspectives - a bit like trying to understand a car crash by switching between multiple moving cameras.
This new method avoids that complexity. Because everything happens within the laser system itself, scientists can observe the results directly, without needing complicated frame-by-frame conversions. This should make future experiments much easier to interpret.
The research was carried out in 2024 and 2025 and involved a broad international collaboration, including Dr Ed Gumbrell's team from AWE plc, Professor Karl Krushelnick's group at the University of Michigan's Center for Ultrafast Optics in the United States of America, and Professor Matt Zepf's Research Group for High Field Physics and Laser Acceleration at the University of Jena in Germany.
The work originated in part from doctoral thesis research by Dr Robin Timmis, jointly supported by the Oxford Centre for High Energy Density Science and the Oxford-Berman-Physics Scholarship scheme until she submitted her thesis for examination in 2024.
Lead author Dr Robin Timmis (Department of Physics, University of Oxford), said: "The discoveries we have made so far are fascinating and it feels like we are just getting started in terms of understanding the rich and complex physics of this mechanism. The simulations suggest that we may have made the most intense source of coherent light ever. I hope we get a chance to return to Gemini soon to confirm this but also to take what we have learnt to larger facilities where we can generate even brighter light."
Senior author Professor Peter Norreys (Department of Physics, University of Oxford), said: "We are excited to have realised this extraordinary result in the laboratory. It is a testament to Robin's exquisite mastery of the subject for her to have obtained the precise experimental conditions that have eluded us for decades. This is a real tribute to the dedication and expertise brought by the other members of my team in Oxford, Brendan Dromey's and Mark Yeung's teams in Queen's University Belfast (especially Jonny Kennedy, Holly Huddleston and Colm Fitzpatrick), CLF Scientists at RAL, AWE plc at Aldermaston, and our esteemed international partners."
Co-author Professor Brendan Dromey from Queen's University Belfast commented: "This work is a blend of laser technology, plasma physics and ultrafast materials science finely tuned to resolve a persistent mismatch between theory and experiment that has frustrated the field for more than two decades."
Funding support was provided by UKRI-EPSRC, including the Ultrafast Nanodosimetry grant (EP/W017245/1), the HEC Plasma Physics Consortium grant for access to the ARCHER2 national supercomputer, and UKRI-STFC supported access to the SCARF supercomputer facility at RAL. Additional support came from the AWAKE2 and John Adams Institute for Accelerator Science grants, the Oxford Clarendon Scholarship Fund, and Living Optics Ltd. Supporting grants from US and German funding bodies contributed through the Michigan and Jena groups respectively.
