Distortions in focusing laser pulses due to spatio-temporal couplings: An analytic description

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Klaus Steiniger - , Helmholtz-Zentrum Dresden-Rossendorf, Center for Advanced Systems Understanding (CASUS) (Author)
  • Fabia Dietrich - , Helmholtz-Zentrum Dresden-Rossendorf, TUD Dresden University of Technology (Author)
  • Daniel Albach - , Helmholtz-Zentrum Dresden-Rossendorf (Author)
  • Michael Bussmann - , Helmholtz-Zentrum Dresden-Rossendorf, Center for Advanced Systems Understanding (CASUS) (Author)
  • Arie Irman - , Helmholtz-Zentrum Dresden-Rossendorf (Author)
  • Markus Loeser - , Helmholtz-Zentrum Dresden-Rossendorf (Author)
  • Richard Pausch - , Helmholtz-Zentrum Dresden-Rossendorf (Author)
  • Thomas Püschel - , Helmholtz-Zentrum Dresden-Rossendorf (Author)
  • Roland Sauerbrey - , Helmholtz-Zentrum Dresden-Rossendorf, Center for Advanced Systems Understanding (CASUS) (Author)
  • Susanne Schöbel - , Chair of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf (Author)
  • Ulrich Schramm - , Helmholtz-Zentrum Dresden-Rossendorf, TUD Dresden University of Technology (Author)
  • Mathias Siebold - , Helmholtz-Zentrum Dresden-Rossendorf (Author)
  • Karl Zeil - , Helmholtz-Zentrum Dresden-Rossendorf (Author)
  • Alexander Debus - , Helmholtz-Zentrum Dresden-Rossendorf (Author)

Abstract

In ultra-short laser pulses, small changes in dispersion properties before the final focusing mirror can lead to severe pulse distortions around the focus and therefore to very different pulse properties at the point of laser-matter interaction, yielding unexpected interaction results. The mapping between far- and near-field laser properties intricately depends on the spatial and angular dispersion properties as well as the focal geometry. For a focused Gaussian laser pulse under the influence of angular, spatial and group-delay dispersion, we derive analytical expressions for its pulse-front tilt, duration and width from a fully analytic expression for its electric field in the time-space domain obtained with scalar diffraction theory. This expression is not only valid in and near the focus but also along the entire propagation distance from the focusing mirror to the focus. Expressions relating angular, spatial and group-delay dispersion before focusing at an off-axis parabola, where they are well measurable, to the respective values in the pulse's focus are obtained by a ray tracing approach. Together, these formulas are used to show in example setups that the pulse-front tilts of lasers with small initial dispersion can become several tens of degrees larger in the vicinity of the focus while being small directly in the focus. The formulas derived here provide the analytical foundation for observations previously made in numerical experiments. By numerically simulating Gaussian pulse propagation and measuring properties of the pulse at distances several Rayleigh lengths off the focus, we verify the analytic expressions.

Details

Original languageEnglish
Article numbere25
JournalHigh power laser science and engineering
Volume12
Publication statusPublished - 18 Dec 2023
Peer-reviewedYes

Keywords

Keywords

  • group-delay dispersion, pulse-front tilt, spatio-temporal couplings, third-order dispersion, ultra-short laser pulses