attosecond pulses from plasmas
The relativistic interaction of an ultra-intense, few-cycle laser pulse with a solid surface has been predicted to result in high-harmonic radiation with unprecedented characteristics. In contrast with atomic high-harmonic generation (HHG), isolated pulse generation appears to be feasible for a broad range of frequencies, up to relative bandwidths of 50% of the entire harmonic spectrum, implying the feasibility of isolated XUV/soft-X-ray pulses of a few attoseconds in duration. Furthermore, the efficiency of few-cycle-driven surface HHG is predicted to surpass that of atomic HHG by several orders of magnitude. If these predictions can be verified, few-cycle-driven surface HHG will open a new chapter in attosecond science.
We pursue these goals with our unique multi-terawatt, few-cycle NIR driver pulses from LWS-20 in the HF-3 beamline. By using multi-cycle pulses, in collaboration with other groups we have recently verified the predicted scaling of harmonic yield with frequency as well as the attosecond phase coherence of surface harmonics. The latter finding implies the feasibility of confining the emitted radiation in a single attosecond pulse when driving the interaction with a few-cycle laser pulse. To this end, we are pursuing carrier-envelope phase control and contrast improvement of our multi-TW few-cycle pulses. Once available, we shall use the high-contrast, waveform-controlled few-cycle terawatt light for driving overdense relativistic plasmas at surfaces. Our efforts are motivated by the prospect of terawatt-scale attosecond pulses and attosecond-pump/attosecond-probe spectroscopy.
contact: G. Tsakiris
, Y. Mikhailova, L. Veisz
contact: G. Tsakiris
, Y. Mikhailova, L. Veisz
references:
Route to intense single attosecond pulses, G. Tsakiris, K. Eidmann, J. Meyer-ter-Vehn and F. Krausz New J. Phys. 8, 19 (2006)
3 D simulations of surface harmonic generation with few-cycle laser pulses, Geissler et al. New J. Phys. 9, 218 (2007)
High harmonic generation in the relativistic limit, B. Dromey et al. Nature Phys. 2, 456 (2006)
Attosecond phase locking of harmonic radiation emitted from laser-produced plasmas, Y. Nomura et al. Nature Phys. published online on 14 December 2008; doi: 10.1038/nphys1155,
tools:
Fig. 1. First temporal characterization of harmonic emission from relativistic plasmas with attosecond resolution indicates sub-femtosecond phase coherence between the harmonics emitted from the relativistic interaction.
Fig. 2. First experiments with few-cycle laser pulses (from LWS-10) have revealed a merger of harmonic lines emitted from the relativistic interaction, indicative of isolated sub-femtosecond pulse emission.
Fig. 3. Calculated production efficiency of bandpass-filtered isolated attosecond pulses emerging from few-cycle-driven surface harmonic generation for three different spectral ranges as a function of the normalized vector potential.