Femtosecond envelope of the high-harmonic emission from ablation plasmas

Stefan Haessler (1, 2) , L B Elouga Bom (3) , O Gobert (2) , J-F Hergott (2) , F Lepetit (2) , M Perdrix (2) , B Carré (2) , T Ozaki (3) , Pascal Salières (2)

1 Photonics Institute
2 SPAM - Service des Photons, Atomes et Molécules
3 INRS - Institut National de la Recherche Scientifique [Québec]

We characterize the temporal profile of the high-order harmonic emission from ablation plasma plumes using cross-correlations with the infrared (IR) laser beam provided by two-photon harmonic+IR ionization of rare gas atoms. We study both non-resonant plasmas (lead, gold and chrome) and resonant plasmas (indium and tin), i.e. plasmas presenting in the singly charged ions a strong radiative transition coinciding with a harmonic order. The cross-correlation traces are found to be very similar for all harmonic orders and all plasma targets. The recovered harmonic pulse durations are very similar to the driving laser, with a tendency towards being shorter, demonstrating that the emission is a directly laser-driven process even in the case of resonant harmonics. This provides a valuable input for theories describing resonant-harmonic emission and opens the perspective of a very high flux tabletop XUV source for applications.

Domaines: Physique Atomique [physics.atom-ph]; Optique [physics.optics]

Stefan Haessler, L B Elouga Bom, O Gobert, J-F Hergott, F Lepetit, et al.. Femtosecond envelope of the high-harmonic emission from ablation plasmas. Journal of Physics B: Atomic and Molecular Physics, 2012, 45, pp.074012. ⟨10.1088/0953-4075/45/7/074012⟩. ⟨hal-01164768⟩