= Two-to-one resonance of dispersive waves
{title2=$\omega(2k)=2\omega(k)$}
A fundamental wave and its second harmonic satisfy <phase matching for a quadratic wave interaction> when $\omega(2k)=2\omega(k)$. The square of the fundamental drives the second harmonic, while its product with the conjugate second harmonic drives the fundamental. Projecting these terms onto the resonant modes gives coupled <amplitude equations> rather than a uniformly valid correction at fixed amplitude.
Back to article page
