Influence of atomic density in high-order harmonic generation

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

Research output: Contribution to journalArticlepeer-review

189 Downloads (Pure)


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
Original languageEnglish
Pages (from-to)148-156
JournalOptical Society of America. Journal B: Optical Physics
Issue number1
Publication statusPublished - 1996

Subject classification (UKÄ)

  • Atom and Molecular Physics and Optics


Dive into the research topics of 'Influence of atomic density in high-order harmonic generation'. Together they form a unique fingerprint.

Cite this