We have demonstrate compression of ultrashort light pulses in the ultraviolet (UV) by impulsively excited molecular wave-packets in nitrogen filled in a 25 cm long hollow waveguide of 128 µm diameter. After compression with CaF2 prisms the pulse duration was determined by XFROG to be 23 fs with a time-bandwidth product of 0.50. For further details are described in our article in Optics Express.

XFROG trace (left), and intensity and phase (right) of the shortest UV-pulse with a duration of 23 fs obtained with a
128 µm waveguide, 25 cm long.