Mechanisms of SCG Based on Third-Order Nonlinearity

In this chapter, the mechanism of the SCG from the third-order nonlinearity process will be reviewed in an intuitive manner. The equations are derived to explain the origin of third-order nonlinear effects, and several diagrams are provided to explain the common nonlinear mechanisms, including SPM and XPM. The mechanisms are divided into two categories according to the pump pulse width. In addition, we emphasize on the special nonlinear mechanisms for SCG in the integrated waveguides, such as multiphoton absorption, free carrier absorption (FCA), and free carrier dispersion (FCD).