Few-cycle optical pulse characterization via cross-polarized wave generation dispersion scan technique.

We demonstrate a dispersion scan (d-scan) pulse characterization scheme employing cross-polarized wave (XPW) generation as a nonlinear optical process. XPW generation is a degenerate four-wave mixing process with no phase-matching limitations. Therefore, its implementation in the d-scan method is a good choice for the characterization of few-cycle pulses in remote spectral regions.

Direct observation of pulse dynamics and self-compression along a femtosecond filament.

We report on the direct experimental observation of pulse-splitting dynamics along a femtosecond filament. The fundamental pulse experiences a significant self-shortening during the propagation leading to pulse durations of 5.3 fs, corresponding to sub-3 cycles, which is measured without external pulse compression.