This mainly theoretical PhD thesis has been done in the framework of high-order harmonics generation on solid targets using 1mJ ultrashort laser pulses (2 optical cycles) at high repetition rate (1kHz), CEP-stabilized. On the one hand, in order to fully use the laser source, I developed a simulation code of hollow-core fiber propagation. The results of this code, associated with an experimental study, allowed to push the energy limitation of this compression technique. On the other hand, I used PIC simulation and I developed a simulation model of CWE in order to quantify its dependence to the laser and plasma parameters. This work first helped to explain the CWE spectrum changes with pulse CEP. Second, by comparing theoretical results with an experimental parametric study, it provided information about the plasma conditions such as density gradient and electronic temperature.
