Who would have guessed that this materials engineer from the Ecole des Mines engineering school in Nancy would become such an expert? “I’ve always been attracted by what I did not know,” said Fabien Quéré. After completing his studies in solid-state physics, Quéré started a Ph.D. in Saclay on the dynamics of electrons in solids, where he discovered the fields of optics and femtosecond lasers (10-15 s). During a post-doc in Canada in 2001, he started exploring the emerging field of attosecond science (10-18 s). “The researchers believed they had already produced attosecond pulses, but had no way of proving it! We had to find a way to measure its duration. Yet such short pulses have to include an ionizing component in their spectrum, in the extreme ultraviolet or X-rays. The solution was to use irradiation to transform the pulses in bunches of electronic waves, which are easier to handle.”

Back in Saclay, he showed that this approach makes it possible, beyond the assessment of the duration of attosecond pulses, to determine the temporal profile of the electric field. Meanwhile, laser intensities continued to increase, exceeding 1018 W/cm2. “I chose to study the interaction between the most intense lasers and a solid target, or what we call “plasma mirrors”. It was a combination of everything I had learned before. I wanted to understand how attosecond pulses can be generated through plasma mirrors. Now, we also investigate the electron beams that are generated during these interactions."

Fabien Quéré was the recipient of several ERC grants, including a Starting Grant in 2010 and an Advanced Grant in 2016. “With the first ERC grant, we conducted research in optics, using plasmas to generate laser harmonics and compressing the pulses over time. The goal of our second ERC grant was to shape a laser field in space and time to induce new effects in laser-plasma interactions,” he said. “But to carry out this research, we needed a tool that combined space and time laser beam characterization, rather than one that only included the space or time aspect. For such unusual lasers, distortions emerge that must be eliminated to advance in the race for higher laser output. This new tool developed by Fabien Quéré and his team is now available for the laser UHI100 in Saclay and will also be a potential valuable addition to the future laser APOLLON at Université Paris-Saclay, and more generally, all femtosecond lasers.