  We study theoretically and experimentally the process of Brillouin light
scattering on an array of silicon disks on a thin Permalloy layer. We show that
phase-resolved Brillouin light scattering microscopy performed on an array of
weakly interacting dielectric nanoresonators can detect nanoscale waves and
measure their dispersion. In our experiment, we were able to map the evolution
of the phase of the spin wave with a wavelength of 209 nm with a precision of 6
nm. These results demonstrate the feasibility of all-optical phase-resolved
characterization of nanoscale spin waves.
