Four Wave Mixing (FWM) is a nonlinear optical process in which interactions between four different light waves result in the generation of new wavelengths. This phenomenon occurs due to the third-order nonlinearity in the medium, typically in materials with high Kerr effect. When three waves with frequencies ω1, ω2, and ω3 propagate through a nonlinear medium, they can interact and produce a fourth wave with frequency ω4, where ω4 = ω1 + ω2 - ω3.
