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

作者：Giulietti A^*; Andre A; Dufrenoy S Dobosz; Giulietti D; Hosokai T; Koester P; Kotaki H; Labate L; Levato T; Nuter R; Pathak N C; Monot P; Gizzi L A

来源：Physics of Plasmas, 2013, 20(8): 082307.

DOI：10.1063/1.4818602

A 65-fs, 800-nm, 2-TW laser pulse propagating through a nitrogen gas jet has been experimentally studied by 90 degrees 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 delta lambda/delta t approximate to 3 angstrom/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(0) %26lt;%26lt; 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.

• 出版日期2013-8
• 单位中国地震局