A micro-sized parametric spin-wave amplifier
  We present the experimental observation of the localized amplification of externally excited spin waves in a transversely in-plane magnetized Ni$_{81}$Fe$_{19}$ magnonic waveguide by means of parallel pumping. By employing microfocussed Brillouin light scattering spectroscopy, we analyze the dependency of the amplification on the applied pumping power and on the delay between the input spin-wave packet and the pumping pulse. We show that there are two different operation regimes: At large pumping powers, the spin-wave packet needs to enter the amplifier before the pumping is switched on in order to be amplified while at low powers the spin-wave packet can arrive at any time during the pumping pulse. 
Thomas Br\"acher, Frank Heussner, Philipp Pirro, Tobias Fischer,   Moritz Geilen, Bj\"orn Heinz, Bert L\"agel, Alexander. A....
cond-mat.mes-hall