Generation and control of Doppler harmonics approaching $10^{22}\textrm{W/cm}^2$ on plasma mirrors

TL;DR

This paper demonstrates the generation of extremely high-intensity Doppler harmonics using plasma mirrors driven by PetaWatt lasers, emphasizing the importance of laser contrast control for efficient high-order harmonic production at intensities exceeding 10^{21} W/cm^2.

Contribution

It introduces a method for controlling laser contrast at sub-picosecond scales to optimize Doppler harmonic generation at unprecedented intensities.

Findings

Harmonics generated at intensities >10^{21} W/cm^2

Precise laser contrast control is crucial for efficiency

Potential applications in high-field quantum electrodynamics

Abstract

In this letter, we report Doppler harmonic generation with a relativistic plasma mirror at unprecedented intensities $>10^{21} ~\textrm{W/cm}^2$ using a PetaWatt-class laser. We show that beyond a few $10^{21} ~\textrm{W/cm}^2$ a precise control of the laser contrast at the sub-picosecond time scale becomes essential to drive the efficient generation of high-order harmonics. Such control is paramount for deploying plasma mirrors in high-field applications at PetaWatt-class laser facilities, including, for instance, their use as intensity boosters in the pursuit of the strong-field regime of quantum electrodynamics.