  High harmonic generation (HHG) enables coherent extreme-ultraviolet (XUV)
radiation with ultra-short pulse duration in a table-top setup. This has
already enabled a plethora of applications. Nearly all of these applications
would benefit from a high photon flux to increase the signal-to-noise ratio and
decrease measurement times. In addition, shortest pulses are desired to
investigate fastest dynamics in fields as diverse as physics, biology,
chemistry and material sciences. In this work, the up-to-date most powerful
table-top XUV source with 12.9 mW in a single harmonic line at 26.5 eV is
demonstrated via HHG of a frequency-doubled and post-compressed fibre laser. At
the same time sub-6 fs XUV pulse duration allows accessing ultrafast dynamics
with an order of magnitude higher photon flux than previously demonstrated.
This concept will greatly advance and facilitate applications of XUV radiation
in science and technology and enable photon-hungry ultrafast studies.
