Magnetostatic surface waves propagation in one-dimensional magnonic crystal obtained by etching of array of grooves (56 width, 0.66 deep, period 98 ) in yttrium-iron garnet film of 4.1 thickness was investigated at first order (three-magnon) parametric instability. It was shown that forbidden gaps don’t form at region of magnonic crystal where propagation of magnetostatic surface waves is nonlinear because of destroy of phase synchronism of incident and reflected waves.
