Scientists unlock new route to extreme light intensities
Oxford physicists have led a significant advance in laser science, demonstrating for the first time a practical route to dramatically boosting the intensity of high-power laser light, possibly creating the most intense source of coherent light ever. The results, published in Nature, could open the door to experiments that probe the fundamental laws of physics by directly interacting light with the quantum vacuum.
Artistic interpretation of coherent harmonic focus (CHF) generation. The laser is focused on a target and the reflected purple beam forms a CHF of extreme intensity that generates matter from light. Credit: Timmis et al. 2026.
The work was led by Professor Peter Norreys and Dr Robin Timmis at the University of Oxford, working in close collaboration scientists at Queen’s University Belfast and 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. For instance, it could allow scientists to recreate conditions so extreme that even empty space begins to behave in unusual ways. At these intensities, light may be able to produce particles directly from the vacuum, offering a way to test long-standing theories about the nature of the universe. This would give researchers a rare opportunity to compare theory with experiment in a completely new regime.
It may even be possible to generate and detect gravitational waves using the coherent harmonic focus, which the researchers aim to explore in the coming years, as well as testing our understanding of quantum field theory in never explored regimes.
“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.”
This work could also help advance laser technologies that can be used right now in industries such as semiconductor manufacturing (for instance, by enabling smaller and more precise features to be etched onto chips), while also supporting the longer term goal of building practical fusion energy systems.
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.’
The study 'Efficiency-optimized relativistic plasma harmonics for extreme fields', has been published in Nature.
The study involved a broad international collaboration, including researchers from AWE plc, the University of Michigan and the University of Jena in Germany.
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