All-optical detection of phase fronts of propagating spin waves in a Ni81Fe19 microstripe

We present the determination of the wavelength and phase of propagating spin waves in magnetic microstructures made of Ni81Fe19 using the shorted end of a coplanar waveguide for local excitation. The spin wave characteristics have been measured by phase resolved Brillouin light scattering microscopy. This recently developed technique allows for the unambiguous experimental visualization of the phase structure of propagating spin waves and is employed here to magnetic microstructures. The results show an excellent agreement with the theoretically predicted spin-wave dispersion relations.