Ultra-intense lasers offer unique opportunities to probe light-matter interactions and develop transformative applications. However, the rapid fluctuations and complex structure of these extreme laser pulses make it challenging to measure their properties in real-time. Typically, hundreds of laser shots are required to measure ultra-intense light pulses. To open avenues for controlling and manipulating light-matter interactions at the highest intensities, researchers at the University of Oxford, in collaboration with Ludwig-Maximilian University and the Max Planck Institute for Quantum Optics, developed a single-shot vector field measurement technique for ultra-intense laser pulses. The technique, called RAVEN (Real-time Acquisition of Vectorial Electromagnetic Near-fields), provides a comprehensive view of the spatiotemporal and polarization structure of ultra-intense pulses, including quantified uncertainties. It could accelerate the development of applications in multiple areas, including high-field physics, laser-matter interactions, and fusion energy. Artist’s illustration of the RAVEN technique, which measures a complex light pulse using micro foci and spectral dispersion, which is then fed into a neural network for retrieval. Courtesy of the University of Oxford/Ehsan Faridi. RAVEN splits the ultra-intense laser beam into two parts. One part of the beam is used to measure how the laser’s wavelength changes over time. The other portion of the beam passes through a birefringent material that separates light with different polarization states. A microlens array records how the wavefront of the laser pulse is structured. An optical sensor captures this information in a single image, from which a computer program reconstructs the full structure of the laser pulse. “Because ultra-intense pulses are confined to such a tiny space and time when focused, there are fundamental limits on how much resolution is actually needed to perform this type of diagnostic,” researcher Andreas Döpp said. “This was a game changer, and meant we could use microlenses, making our setup much simpler.” In contrast to previous single-shot methods, the development of the diagnostic is informed by systematic considerations of the desired quantity; thus, the recovery of the field at focus, within uncertainty bounds, can be guaranteed. The researchers demonstrated the efficacy of RAVEN on systems ranging from high-repetition-rate oscillators to petawatt-class lasers. When the technique was tested on the ATLAS-3000 petawatt-class laser in Germany, it uncovered small distortions and wave shifts in the laser pulse that were previously impossible to measure in real-time — a discovery that allowed the team to fine-tune the instrument. These distortions, known as spatiotemporal couplings, can significantly affect the performance of high-intensity laser experiments. Owing to its fast construction time, RAVEN allows for online measurement and optimization at ultra-intense laser facilities like the ATLAS-3000 with repetition rates of about 1 Hz. “Our approach enables, for the first time, the complete capture of an ultra-intense laser pulse in real-time, including its polarization state and complex internal structure,” researcher Sunny Howard said. “This not only provides unprecedented insights into laser-matter interactions but also paves the way for optimizing high-power laser systems in a way that was previously impossible.” With RAVEN, there is potential for performance gains across a range of applications. RAVEN’s ability to provide comprehensive pulse characterization in real time enables the online optimization of laser parameters, potentially making experiments in plasma physics, particle acceleration, and high-energy density science more accurate. By providing crucial data on system performance, including shot-to-shot fluctuations and polarization information, RAVEN could improve the predictive power of computational models and AI-powered simulations in ultra-intense laser physics. RAVEN’s single-shot, full-vector-field characterization capability allows subtle effects and transient phenomena that were previously undetectable to be observed, which could drive improvements in laser design and control. RAVEN also provides significant time savings, since multiple shots are not required to fully characterize the laser pulse. “Where most existing methods would require hundreds of shots, RAVEN achieves a complete spatiotemporal characterization of a laser pulse in just one,” professor Peter Norreys said. “This not only provides a powerful new tool for laser diagnostics but also has the potential to accelerate progress across a wide range of ultra-intense laser applications, promising to push the boundaries of laser science and technology.” RAVEN could also spur exploration into inertial fusion energy devices in the laboratory — a key step toward generating fusion energy at a scale sufficient to power the populace. Inertial fusion energy devices use ultra-intense laser pulses to generate highly energetic particles within a plasma, which then propagate into the fusion fuel. Accurate knowledge of the focused laser pulse intensity to target is required to optimize the fusion yield, and could be provided by RAVEN. The researchers hope to expand the use of RAVEN to a broader range of laser facilities and explore its potential to optimize inertial fusion energy research, laser-driven particle accelerators, and high-field quantum electrodynamics experiments. The research was published in Nature Photonics (www.doi.org/10.1038/s41566-025-01698-x).