Apollon power laser infrastructure explained in video

At the end of 2024, the first experimental campaign using two petawatt-(PW) beams began at Apollon. Located on CEA's Orme des Merisiers site, this 4,000 m² research facility produces laser beams that are both very powerful and very short. It is run by CNRS and Ecole Polytechnique at the Laboratory for the Use of Intense Lasers (LULI*). The Applied Optics Laboratory (LOA*) and the Institut d'Optique Graduate School are also partners in the project.

A total of four laser beams will be made available to the international scientific community through a call for projects. Two of the beams exceed petawatt power, a characteristic shared by only three other facilities worldwide (two of which are currently under construction). The main beam currently reaches 4 PW with a pulse duration of just 18 millionths of a billionth of a second (femtosecond). Eventually, this beam will have a power of 10 PW.

To generate these distinctive laser features, Apollon uses the CPA (“Chirped Pulse Amplification”) technique discovered by Donna Strickland and Gérard Mourou, and awarded the 2018 Nobel Prize in Physics. This technique makes it possible to greatly amplify a short pulse, by stretching it temporally before recompressing it. These steps are carried out on the various floors of Apollon's large laser hall and are detailed in the video below.

When focused, these lasers can reach extreme electric fields and intensities to probe matter, or even the vacuum, under unprecedented conditions. Two experimental rooms are dedicated to the exploration of fields about which little is known. These include quantum electrodynamics, the theory that brings together electromagnetism and quantum physics, which can be probed “in the strong field regime”, where so-called non-linear effects become important, and whose observation will offer new insights.

High intensities will also reproduce the conditions present in astrophysical phenomena in order to reconstitute them in the laboratory. This includes, for example, the study of the interior of stars, or the formation of chemical elements (nucleosynthesis). Complex states of matter, at the intersection between condensed matter and plasmas, known as Warm Dense Matter, will also be investigated. 

Finally, the interaction of lasers with the target on which they are focused creates particles (electrons, protons, photons of different wavelengths such as X-rays). The study of these secondary sources of radiation is another area of research covered by Apollon, with potential biomedical applications. To find out more about how this research is carried out, here's a video example of the work carried out by Julien Fuchs, a CNRS researcher at LULI.

*LULI: a joint research unit CEA, CNRS, Sorbonne Université, École polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France

LOA: a joint research unit CNRS, École Polytechnique, ENSTA, Institut Polytechnique de Paris, 91120 Palaiseau, France