MI peak gain at K_peak = sqrt(gamma*P); g_max = gamma*P via Courant-Fischer

Modulation-instability peak gain (anomalous-dispersion regime, |beta_2| = 1 normalized). From framework F9 (Courant-Fischer), the MI growth rate is g_MI(K) = |K|*sqrt(2*gamma*P - K^2) with gamma*P the nonlinear parameter. Maximise: d/d-K…