Four-wave-mixing oscillation threshold
= Four-wave-mixing oscillation threshold
{title2=$\kappa L=\pi/2$}
The first zero of $\cos\kappa L$ makes the homogeneous opposite-end boundary problem singular. Its undepleted-pump treatment admits a nontrivial field without an imposed signal, indicating a parametric oscillation threshold. Depletion, saturation and the actual noise-seeded dynamics determine finite fields near threshold.