Towards lasers powerful enough to investigate a new type of physics

In an article that made the cover of the magazine. Applied Physics Lyrics, an international team of researchers has demonstrated an innovative technique to increase the intensity of lasers. This approach, based on the compression of light pulses, would allow reaching an intensity threshold for a new type of physics that has never been explored before: the phenomena of quantum electrodynamics.

The researchers Jean-Claude Kieffer of the National Institute for Scientific Research (INRS), EA Khazanov of the Institute of Applied Physics of the Russian Academy of Sciences and in France Gérard Mourou, professor emeritus of the Ecole Polytechnique, who received the Nobel Prize in Physics in 2018, they have chosen another direction to achieve a power of around 10^{2. 3} watts (W). Instead of increasing the laser energy, they decrease the pulse duration to just a few femtoseconds. This would keep the system within a reasonable size and reduce operating costs.

To generate the shortest possible pulse, researchers are exploiting the effects of nonlinear optics. “A laser beam is sent through an extremely thin and perfectly homogeneous glass plate. The particular behavior of the wave within this solid medium broadens the spectrum and allows a shorter pulse when it is compressed again at the plate output “explains Jean-Claude Kieffer, co-author of the study published online June 15, 2020 in the journal Applied Physics Lyrics.

Applied Physics Lyrics, Volume 116, Number 24 published on June 15, 2020. Credit: AIP Publishing “>

Applied Physics Lyrics, Volume 116, Number 24 published on June 15, 2020. Credit: AIP Publishing”/>

Installed at the Advanced Laser Light Source (ALLS) facility at INRS, the researchers limited themselves to an energy of 3 joules for a pulse of 10 femtoseconds, or 300 terawatts (10¹² W) They plan to repeat the experiment with an energy of 13 joules for 5 femtoseconds, or an intensity of 3 petawatts (10^fifteen W) “We would be among the first in the world to reach this power level with a laser that has such short pulses,” says Professor Kieffer.

“If we achieve very short pulses, we enter into classes of relativistic problems. This is an extremely interesting direction that has the potential to take the scientific community to new horizons,” says Professor Kieffer. “It was a very pleasant job that solidified the primary potential of this technique,” concludes Gérard Mourou.

Provided by Institut national de la recherche scientifique – INRS