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Title: Space- and time-resolved observation of extreme laser frequency upshifting during ultrafast-ionization

A 65-fs, 800-nm, 2-TW laser pulse propagating through a nitrogen gas jet has been experimentally studied by 90° Thomson scattering. Time-integrated spectra of scattered light show unprecedented broadening towards the blue which exceeds 300 nm. Images of the scattering region provide for the first time a space- and time-resolved description of the process leading quite regularly to such a large upshift. The mean shifting rate was as high as δλ/δt ≈ 3 Å/fs, never observed before. Interferometry shows that it occurs after partial laser defocusing. Numerical simulations prove that such an upshift is consistent with a laser-gas late interaction, when laser intensity has decreased well below relativistic values (a{sub 0}≪ 1) and ionization process involves most of the laser pulse. This kind of interaction makes spectral tuning of ultrashort intense laser pulses possible in a large spectral range.
Authors:
; ; ;  [1] ; ; ;  [2] ;  [1] ;  [3] ;  [3] ;  [4] ;  [5] ; ;  [1] ;  [3] ;  [6]
  1. Intense Laser Irradiation Laboratory, Istituto Nazionale di Ottica, CNR Campus, Via Moruzzi, 1, 56124 Pisa (Italy)
  2. CEA-Saclay DSM-IRAMIS-SPAM, 91191 Gif sur Yvette (France)
  3. (Italy)
  4. Photon Pioneer Center, Osaka University, Osaka (Japan)
  5. Japan Atomic Energy Agency (JAEA), Kizugawa, Kyoto (Japan)
  6. CEA-Arpajon DIF-DAM, Arpajon (France)
Publication Date:
OSTI Identifier:
22227894
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 20; Journal Issue: 8; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; COMPUTERIZED SIMULATION; INTERFEROMETRY; LASERS; LIGHT SCATTERING; NITROGEN; NUMERICAL ANALYSIS; PLASMA DIAGNOSTICS; PLASMA JETS; PLASMA SIMULATION; RELATIVISTIC PLASMA; SPECTRAL SHIFT; THOMSON SCATTERING; TIME RESOLUTION; VISIBLE RADIATION