Kerr effect induced transient group-velocity dispersion of fused silica measured via real-time MIIPS and spectral interferometry

The optical Kerr effect (OKE) produces an intensity dependent refractive index change which gives rise to self-phase modulation (SPM). SPM leads to changes in laser pulse duration by affecting the phase of the laser pulse. Here we explore the transient behavior of fused silica and find that the OKE-induced phase changes are accompanied by significant changes in the magnitude and sign of the group velocity dispersion (GVD). We find that material dispersion, which is a key parameter for all femtosecond laser applications, is not a constant and this should be taken into consideration.