Characterization of Partially Coherent Ultrashort XUV Pulses

Ultrafast metrology often considers that the measured light pulse is fully coherent, or equivalently that its properties are stable enough to enable its description by a given time-dependent electric field. However, these conditions are never entirely satisfied in practice, especially in the domain of ultrashort extreme-ultraviolet (XUV) sources. To sort out this issue, we have adapted Frequency-Resolved Optical Gating (FROG), the well-known technique for pulse characterization, to enable the measurement of partially coherent XUV pulses in the femtosecond and attosecond range. Especially, this technique allows one to overcome the sources of decoherence that normally prevent pulse measurement, such as the spectrometer resolution or the presence of XUV/laser arrival time jitter.