Synchronized pulses generated at 20 eV and 90 eV for attosecond pump–probe experiments

Journal name:
Nature Photonics
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Published online

The development of attosecond pulses across different photon energies is an essential precursor to performing pump–probe attosecond experiments in complex systems, where the potential of attosecond science1 can be further developed2, 3. We report the generation and characterization of synchronized extreme ultraviolet (90 eV) and vacuum ultraviolet (20 eV) pulses, generated simultaneously via high-harmonic generation. The vacuum ultraviolet pulses are well suited for pump–probe experiments that exploit the high photo-ionization cross-sections of many molecules in this spectral region4 as well as the higher photon flux due to the higher conversion efficiency of the high harmonic generation process at these energies5. We temporally characterized all pulses using the attosecond streaking technique6 and the FROG-CRAB retrieval method7. We report 576 ± 16 as pulses at 20 eV and 257 ± 21 as pulses at 90 eV. Our demonstration of synchronized attosecond pulses at different photon energies, which are inherently jitter-free due to the common-path geometry implemented, offers unprecedented possibilities for pump–probe studies.

At a glance


  1. Geometry for the production of simultaneous attosecond XUV and VUV pulses.
    Figure 1: Geometry for the production of simultaneous attosecond XUV and VUV pulses.

    ag, The NIR pulse is focused in two in-line Kr and Ne gas targets. The radiation propagates collinearly and is spectrally filtered with different foil filters mounted in a row (e) to allow the selection of any combination of photon energies by appropriate alignment of the filter assembly, as shown in the main set-up and in f and g. The transmitted radiation is then focused in front of an electron time-of-flight spectrometer with a two-part mirror providing the time delay between the selected pulses (the inner part of this concave mirror can be moved precisely with respect to the outer annular part using a piezo stage). The spectral properties of the generated high harmonics and the filters are shown in ad. The solid lines in a and b are the spatially-integrated high-harmonic spectra without any spectral filtering. The dashed lines in a and b give the transmission spectra of the Sn and Zr filters and the reflectivity of the MoSi mirror.

  2. XUV pulse characterization.
    Figure 2: XUV pulse characterization.

    The isolated attosecond pulse in the XUV is characterized with the Kr jet off (left column) and on (right column). ad, The measured traces (a,b) are well reproduced by the retrieved ones (c,d). e,f, The temporal characteristics are preserved. g,h, The spectrum (blue line), together with the spectral phase (red line). The shaded areas represent the mean ± one standard deviation.

  3. VUV pulse characterization.
    Figure 3: VUV pulse characterization.

    The photoelectron wave packets generated with VUV radiation filtered by a Sn foil were streaked with the few-cycle infrared pulse in a similar manner as in Fig. 2, with the Ne gas jet off (left column) and on (right column). ad, The retrieved traces (c,d) reproduce the measured ones (a,b). e,f, Temporal intensity profiles, which exhibit pre and post pulses as expected from selecting two distinct harmonics, but the full-width at half-maximum (FWHM) is comparable in the two cases and agrees with the pulse shape obtained from the TDSE simulations (dashed black line, FWHM = 575 as). g,h, Amplitude (blue) and phase (red) of the retrieved spectra. The shaded areas represent the mean ± one standard deviation.


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  1. Blackett Laboratory, Imperial College, London SW7 2AZ, UK

    • D. Fabris,
    • T. Witting,
    • W. A. Okell,
    • D. J. Walke,
    • P. Matia-Hernando,
    • T. R. Barillot,
    • J. P. Marangos &
    • J. W. G. Tisch
  2. Institut für Theoretische Physik and Centre for Quantum Engineering and Space-Time Research, Leibniz Universität Hannover, Appelstraße 2, Hannover D-30167, Germany

    • J. Henkel &
    • M. Lein


D.F. and T.W. contributed equally as first authors. D.F. and T.W. performed (with contributions from W.A.O.) the streaking experiments. J.W.G.T. and J.P.M. conceived and designed the experiment. P.M.-H. and D.J.W. performed the absolute photon flux calibration. J.H. and M.L. provided the TDSE calculations and theoretical support. D.F. performed the analysis of the data. D.F., J.W.G.T. and J.P.M. wrote the manuscript with contributions from T.W., T.R.B., J.H. and W.A.O. All authors discussed the results and the analysis of the data.

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