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Influence of atomic density in high-order harmonic generation

Altucci, C; Starczewski, Tomas; Mevel, E; Wahlström, Claes-Göran LU ; Carre, B and L'Huillier, Anne LU (1996) In Optical Society of America. Journal B: Optical Physics 13(1). p.148-156
Abstract
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... (More)
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 (Less)
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Optical Society of America. Journal B: Optical Physics
volume
13
issue
1
pages
148 - 156
publisher
Optical Society of America
external identifiers
  • Scopus:0030532380
ISSN
0740-3224
DOI
10.1364/JOSAB.13.000148
language
English
LU publication?
yes
id
9087fd23-3bba-4488-ab69-d0d7e0785429 (old id 2257190)
date added to LUP
2012-02-24 15:18:56
date last changed
2016-10-13 04:35:49
@misc{9087fd23-3bba-4488-ab69-d0d7e0785429,
  abstract     = {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},
  author       = {Altucci, C and Starczewski, Tomas and Mevel, E and Wahlström, Claes-Göran and Carre, B and L'Huillier, Anne},
  issn         = {0740-3224},
  language     = {eng},
  number       = {1},
  pages        = {148--156},
  publisher    = {ARRAY(0xb373db8)},
  series       = {Optical Society of America. Journal B: Optical Physics},
  title        = {Influence of atomic density in high-order harmonic generation},
  url          = {http://dx.doi.org/10.1364/JOSAB.13.000148},
  volume       = {13},
  year         = {1996},
}