Characterization of few-fs deep-UV dispersive waves by ultra-broadband transient-grating XFROG.

A multi-shot transient-grating cross-correlation frequency-resolved optical gating (FROG) is implemented for the characterization of nanojoule-scale, few-femtosecond, deep-ultraviolet pulses. In theory, the system can characterize pulses with a bandwidth extending from below 200 nm to above 1.5 μm. It is experimentally shown that a 200 THz (50 nm) wide dispersive wave centered at 275 nm, generated in a gas-filled HC-PCF, has a temporal duration of 4 fs. The numerical simulations agree well with the experiment. The results confirm that dispersive wave emission in a gas-filled HC-PCF can be used as a novel source of ultrashort UV pulses in a range of applications, for example, ultrafast UV pump-probe spectroscopy.