How to characterize intense femtosecond lasers pulses by cross-phase modulation

With the rapid progress in femtosecond laser technology, the accurate measurement of pulse time profile becomes a more and more important issue. Several diagnostics techniques have been demonstrated, which go beyond the 2/spl omega/ autocorrelation method. We show in this presentation that methods based on spectrally resolved cross-phase modulation (XPM) provide a powerful and simple tool for femtosecond pulses analysis. Two distinct physical processes are exploited: multiphoton ionization (MPI) in a neutral gas or instantaneous optical Kerr effect (OKE) in a transparent solid.