4. Other non-linear effects

In the previous section, the non-linear effect studied was the parametric process related to four-wave mixing. The equations are interesting for understanding the basis of parametric amplification when the pump is not depopulated. However, at high conversion efficiencies, both the signal and the complementary extract a significant portion of the pump's power. This decrease in power has a significant impact on the dynamics of amplification through the phase matching condition, and must therefore be taken into account. For example, the gain decreases at saturation and the maximum shifts towards the pump frequency. This impact can be estimated by considering a low-power pulse, although more realistic interpretations can be obtained by using numerical simulation