A tunable ultrafast spectrometer based on hollow waveguides: Demonstration in violet-blue

We demonstrate an ultrafast spectrometer based on the hollow-fiber technique with sub-50-fs time resolution in the violet-blue wavelength range at 1-kHz repetition rates. We use an intense compressed near-infrared continuum as a seed for upconversion to the range 360-450 nm with 3-30 mu J energies and 40-50 fs durations, We show that implementation of this scheme allows a flexible two-colour two-pulse generation to be used in spectroscopic experiments. We apply this two-colour pump-probe set-up in a study of the ultrafast hydrogen-transfer dynamics of 2-(2'-hydroxy-5'-methylphenyl)-benzotriazole.