Microwave spectral analysis by means of non-resonant parametric recovery   of spin-wave signals in a thin magnetic film
  We report on the storage and non-resonant parametric recovery of microwave signals carried by a dipolar surface spin-wave pulse in a thin ferrimagnetic film. The information about the intensity of the spectral components of the signal within a narrow frequency band is saved due to the excitation of a dipolar-exchange standing spin-wave mode across the film thickness and is afterwards restored by means of parametric amplification of this mode. The intensity of the restored signal measured for varying shifts between the signal carrier frequency and half of the pumping frequency, which is equal to the frequency of the standing mode, reveals information about the entire frequency spectrum of the input microwave signal. 
S. Sch\"afer, A.V. Chumak, A.A. Serga, G.A. Melkov, and B. Hillebrands