Investigating nonlinear femtosecond pulse propagation with frequency-resolved optical gating

Frequency-resolved optical gating (FROG) is used to investigate nonlinear pulse propagation in normally dispersive media. We present high-dynamic-range measurements of broad-bandwidth femtosecond pulses that result from nonlinear propagation in fused silica and compare these measurements with a (3+1)-dimensional modified nonlinear Schrodinger equation. We also demonstrate the ability of FROG to provide information about a noninstantaneous nonlinearity in methanol. In this case, the instantaneous nonlinear index and the time response of the noninstantaneous nonlinearity are used as fit parameters in a (1+1)-dimensional model.