High-Order Harmonic Generation in the Highly Relativistic Regime

ORAL

Abstract

The mechanisms of high-order harmonic generation (HOHG) by the reflection of an intense laser pulse from an overdense plasma surface can provide information about the complex laser-plasma coupling. Under p-polarized interactions, “vacuum heating” has been demonstrated to drive the coherent wake emission (CWE) mechanism responsible for radiation extending to the plasma frequency. However, in s-polarized interactions, robust harmonic generation has not been observed, as relativistic intensities are required for the JxB force to be efficient. In our experimental campaign at the Advanced Laser for Extreme Photonics (ALEPH) facility, high brightness radiation at integer multiples of the fundamental frequency were observed in the specular reflection of highly intense, ultra-high contrast, and s-polarized laser pulses. For copper foils irradiated at ∽1020 W/cm2, the radiation spectra displayed a cutoff at the plasma frequency, resembling the CWE mechanism. Spectra obtained from particle-in-cell simulations show how the JxB force can generate radiation at and beyond the plasma frequency.

This work was supported by the NSF under awards PHY-2308982, PHY-1753165, and DMR-1548924; and by the DOE under award DE-SC0023504.

*This work was supported by the NSF under awards PHY-2308982, PHY-1753165, and DMR-1548924; and by the DOE under award DE-SC0023504.

–

Presenters

  • Victor Flores

    • University of California, Irvine

Authors

  • Victor Flores

    • University of California, Irvine

  • Hunter G Allison

    • University of California, Irvine

  • Danny W Attiyah

    • University of California, Irvine

  • Nick Beier

    • University of Alberta

  • Philip Charles Efthimion

    • Princeton Plasma Physics Laboratory (PPPL)

  • Kirk A Flippo

    • Los Alamos National Laboratory (LANL)

  • Lan Gao

    • Princeton Plasma Physics Laboratory (PPPL)

  • Christopher Gardner

    • University of California, Irvine

  • Stephanie B Hansen

    • Sandia National Laboratories

  • Kenneth Wayne Hill

    • Princeton Plasma Physics Laboratory
    • Princeton University

  • Reed C Hollinger

    • Colorado State University

  • Vigneshvar Senthilkumaran

    • University of Alberta

  • Ronnie Lee Shepherd

    • Lawrence Livermore National Laboratory

  • Vyacheslav N Shlyaptsev

    • Colorado State University

  • Amina E Hussein

    • Univ of Alberta

  • Jorge J Rocca

    • Colorado State University

  • Franklin J Dollar

    • University of California, Irvine