Two-wave mixing in a quadratic nonlinear medium:bifurcations, spatial instabilities, and chaos

We present the qualitative dynamics of parametric mixing of two waves in a quadratic nonlinear medium by introducing a reduced phase-plane description. We find the nonlinear frequency-conversion eigenmodes and their bifurcations and instabilities. We discuss applications of this description to the phase dependence of seeded second-harmonic generation, frequency division, and spatial chaos in a medium with periodic mismatch