arXiv subjects

Kosta Oubrerie

Publications and source records attributed to Kosta Oubrerie.

5 recordsLinked to original sources

arXiv2026

Fundamental limit of intensity scaling for harmonic generation on plasma mirrors

Plasma mirrors have the potential to considerably boost the intensity of ultra-intense laser pulses through high-order harmonic generation, offering a promising route to the extreme fields required for probing the strong-field regime of quantum electrodynamics (SF-QED). This prospect relies on the favorable scaling of harmonic generation with increasing laser intensity, a longstanding assumption that has remained untested at extreme intensities. Combining the first measurements of Doppler harmonic generation approaching $10^{22}\,\mathrm{W/cm^2}$ with advanced particle-in-cell modeling, our study reveals fundamental limitations to this scaling. We notably observe a strong reduction of the harmonic yield as the laser intensity is increased, and show using simulations that this originates from the interaction of the sub-picosecond laser pedestal with the plasma mirror. This pedestal drives a rapid evolution of the plasma surface, through radiation-pressure compression and surface modulations, which progressively suppress harmonic generation. By extending our simulations up to intensities of $10^{23}\,\mathrm{W/cm^2}$, we show that this evolution accelerates strongly with increasing intensity, eventually leading to plasma mirror disruption on the timescale of the main laser pulse itself, making pulse duration, in addition to temporal contrast, a second key parameter for efficient harmonic generation. These results reveal the fundamental limits of the intensity scaling of harmonic generation from plasma mirrors and establish the conditions required to preserve efficient harmonic generation at extreme intensities, providing critical guidance for their use as intensity boosters toward the SF-QED regime.

physics.plasm-ph↗

arXiv2025

Quasi-monoenergetic multi-GeV electron acceleration in a plasma waveguide

Laser-plasma accelerators present a promising alternative to conventional accelerators. To fully exploit the extreme amplitudes of the plasma fields and produce high-quality beams, precise control over electron injection into the accelerating structure is required, along with effective laser pulse guiding to extend the acceleration length. Recent studies have demonstrated efficient guiding and acceleration using hydrodynamic optically field-ionized (OFI) plasma channels. This guiding technique has also been combined with controlled electron injection to produce high-quality electron beams at the GeV level using a 50 TW laser. The present work extends these results to higher laser energies, demonstrating the generation of quasi-monoenergetic electron beams with peak energies exceeding 2 GeV, for a PW-class laser.

physics.plasm-ph↗

arXiv2021

Controlled acceleration of GeV electron beams in an all-optical plasma waveguide

Laser-plasma accelerators produce electric fields of the order of 100 GV/m, more than 1000 times larger than radio-frequency accelerators. Thanks to this unique field strength, they appear as a promising path to generate electron beams beyond the TeV, for high-energy physics. Yet, large electric fields are of little benefit if they are not maintained over a long distance. It is therefore of the utmost importance to guide the ultra-intense laser pulse that drives the accelerator. Reaching very high energies is equally useless if the properties of the electron beam change completely shot to shot. While present state-of-the-art laser-plasma accelerators can already separately address guiding and control challenges by tweaking the plasma structures, the production of beams combining high quality and high energy is yet to be demonstrated. Here we use a new approach for guiding the laser, and combined it with a controlled injection technique to demonstrate the reliable and efficient acceleration of high-quality electron beams up to 1.1 GeV, from a 50 TW-class laser.

physics.plasm-ph↗

arXiv2021

Axiparabola: a new tool for high-intensity optics

An axiparabola is a reflective aspherical optics that focuses a light beam into an extended focal line. The light intensity and group velocity profiles along the focus are adjustable through the proper design. The on-axis light velocity can be controlled, for instance, by adding spatio-temporal couplings via chromatic optics on the incoming beam. Therefore the energy deposition along the axis can be either subluminal or superluminal as required in various applications. This article first explores how the axiparabola design defines its properties in the geometric optics approximation. Then the obtained description is considered in numerical simulations for two cases of interest for laser-plasma acceleration. We show that the axiparabola can be used either to generate a plasma waveguide to overcome diffraction or for driving a dephasingless wakefield accelerator.

physics.optics↗

arXiv2021

Measurement and Control of Main Spatio-Temporal Couplings in a CPA Laser Chain

We report a straightforward method to control main spatio-temporal couplings in a CPA laser chain system using a specially designed chromatic doublet in a divergent beam configuration. The centering of the doublet allows for the control of the spatial chirp of the CPA laser chain, while its longitudinal position in the divergent beam enables the control of the amount of longitudinal chromatism in a wide dynamic range. The performance of this technique is evaluated by measuring main spatio-temporal couplings with a simple method, based on an ultrafast pulse shaper, which allows for a selection of narrow windows of the spectrum.

physics.optics↗