Laboratoire d'Optique Appliquée


May 11 2022


14 h 00 min

Generation of near-single-cycle duration pulses for relativistic laser-matter interaction at high repetition rate

This experimental thesis took place at the Laboratoire d’Optique Appliquée (Palaiseau, France) on a laser system capable of generating pulses close to the optical cycle in duration with energies of several mJ at a rate of 1 kHz: the Dark Room. Thanks to this system, we study the laser-matter interaction in the relativistic regime at high rate. We manage, on the one hand, in gas jets, to accelerate electrons in the wake of the laser up to an energy of a few MeV; and on the other hand, by interaction with plasma mirrors, to generate high order harmonics which are associated in the time domain with attosecond pulses. Despite the technical prowess of these experiments, the properties of the XUV and electron beams thus generated are still not very compatible with leading downstream applications. The objective of this thesis was to obtain beams with stable properties, which was achieved by making the laser system more stable and reliable, as well as by implementing a fast control loop of the envelope-carrier phase of the pulses. laser. By varying this envelope-carrier phase, we were notably able to generate single attosecond pulses by forming a temporal gate of relativistic intensity on the surface of the plasma mirror, as well as to produce electron beams stable in energy and direction, by controlling the injection of electrons into the laser-plasma accelerator. In addition, different interaction regimes with plasma mirrors have been studied experimentally, such as the acceleration of electrons in long plasma density gradients, and the acceleration of protons at the front face of the target, in order to better understand the dynamics of laser-plasma interaction.