› topics › physics-andSignal Processing - an overview | ScienceDirect Topics Figure 17.41 shows numerical simulations of the phase response of a nonlinear silicon waveguide in a pump-probe configuration, using the model described in reference [156]. A 5 ps pump pulse is injected into the waveguide, and a 5 ps probe pulse is then stepped in time across the pump pulse to monitor the response of the waveguide.