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Tuesday, 21 June 2011

JC: Rashid: Attosecond emission from chromium plasma

We present the first measurement of the attosecond emission generated from underdense plasma produced on a solid target. We generate high-order harmonics of a femtosecond Ti:sapphire laser focused in a weakly ionized underdense chromium plasma. Using the .Reconstruc- tion of Attosecond Beating by Interference of Two-photon Transitions. (RABITT) technique, we show that the 11thto the 19thharmonic orders form in the time domain an attosecond pulse train with each pulse having 300 as duration, which is only 1.05 times the theoretical Fourier transform limit. Measurements reveal a very low positive group delay dispersion of 4200 as2. Beside its fundamental interest, high-order harmonic generation in plasma plumes could thus provide an intense source of attosecond pulses for applications.