Fig. 4: An example transient output pulse energy (E3) as a function of delay between the input pulses (the k1 and k2 beams) for one of the Si:P samples far from resonance.
From: Highly efficient THz four-wave mixing in doped silicon
The signal is a third-order autocorrelation of the pulse temporal profile. This autocorrelation signal appears Gaussian to a good approximation (red line) with r.m.s. width σt = 7.5 ps, so the inferred r.m.s. duration of the pump beams is \({t}_{0}=\sqrt{2/3}{\sigma }_{t}=\) 6.1 ps
