Nonadiabatic interaction of a propagating wave packet with localized parametric pumping

The interaction of a propagating wave packet (carrier frequency ω, wave number $k)$ with nonadiabatic parametric pumping, localized in a region of size the order of the carrier wavelength L~λ=2π/k, is studied experimentally in a system of dipolar spin waves in a ferrite film. It is shown that the three-wave parametric interaction ω+ω^'=ωₚ leads to the formation of both contrapropagating (k^'=-k) and copropagating (k^'=k) idle wave packets of carrier frequency ω^'. A system of equations derived for the packet envelopes gives a quantitative description of the observed random modulation of the output signal caused by the interference of the input and copropagating idle wave packets.