Studying the Role of Nonlinear Medium Thickness in the Characterization of 1.5-Cycle Pulses using XPW Dispersion Scan

When light sources approach the single cycle limit, both their dispersion compensation as well as pulse characterization become increasingly challenging. As all pulse characterization methods rely on some optical non-linearity, concomitant phase matching issues or dispersive broadening inside the nonlinear medium may severely corrupt the measurement result. One of the best suited methods for characterizing sub-2-cycle pulses is the dispersion scan (d-scan) technique that traditionally relies on second harmonic generation (SHG) as the nonlinear interaction [1]. However, using frequency conversion as a nonlinearity phase matching is the dominant limitation obscuring smaller propagation effects. By using cross-polarized wave (XPW) generation [2] in the d-scan arrangement [3], where no frequency conversion takes place, the phase matching issues are eliminated, uncovering the dispersion and self-phase modulation (SPM), inherently present in the propagation.