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Anne L'Huillier

Anne l'Huillier

Professor

Anne L'Huillier

Influence of atomic density in high-order harmonic generation

Author

  • C Altucci
  • Tomas Starczewski
  • E Mevel
  • Claes-Göran Wahlström
  • B Carre
  • Anne L'Huillier

Summary, in English

We have investigated how high-order harmonics generated in rare gases depend on the atomic density. The peak and the profile of the atomic density in the interaction region were measured as a function of the backing pressure and the distance from the nozzle by a differential interferometry technique, The conversion efficiency for the harmonics in the plateau was found to increase approximately quadratically over the entire range of peak pressures investigated (3-80 mbar). The intensity of the harmonics in the cutoff region, in contrast, increased only until an optimum peak pressure was reached, beyond which it decreased. This optimum peak pressure was found to be dependent on both the laser intensity and the process order. To understand this effect, we have performed extensive propagation calculations of both the fundamental and the harmonic fields, using ionization rates and dipole moments from a tunnel ionization model. We obtained good agreement with the experimental results. The observed effect is attributed to ionization-induced defocusing of the fundamental laser beam, which reduces the peak intensity obtained in the medium and shortens the extent of the plateau. (C) 1996 Optical Society of America

Department/s

  • Atomic Physics

Publishing year

1996

Language

English

Pages

148-156

Publication/Series

Optical Society of America. Journal B: Optical Physics

Volume

13

Issue

1

Document type

Journal article

Publisher

Optical Society of America

Topic

  • Atom and Molecular Physics and Optics

Status

Published

ISBN/ISSN/Other

  • ISSN: 0740-3224