Space- and time-resolved observation of extreme laser frequency upshifting during ultrafast-ionization
- Intense Laser Irradiation Laboratory, Istituto Nazionale di Ottica, CNR Campus, Via Moruzzi, 1, 56124 Pisa (Italy)
- CEA-Saclay DSM-IRAMIS-SPAM, 91191 Gif sur Yvette (France)
- Photon Pioneer Center, Osaka University, Osaka (Japan)
- Japan Atomic Energy Agency (JAEA), Kizugawa, Kyoto (Japan)
- CEA-Arpajon DIF-DAM, Arpajon (France)
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.
- OSTI ID:
- 22227894
- Journal Information:
- Physics of Plasmas, Vol. 20, Issue 8; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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