  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.
