Three-wave mixing
= Three-wave mixing
An interaction among three <waves> mediated by a second-order <nonlinear optical susceptibility>. In <sum-frequency generation>, two input <angular frequencies> satisfy $\omega_3=\omega_1+\omega_2$. The same coupling permits reverse conversion. <Phase matching> determines whether successive generated contributions reinforce; the <Manley-Rowe relations> express the associated lossless exchange constraints.