Near-field theoretical study of a magneto-optical grating

We propose a theoretical description of a near-field observation of a magneto-optical grating. We consider a scanning tunnelling optical microscopy (STOM) experiment where the sample is a thin isotropic magnetic material. We choose a transverse geometry: the magnetization is perpendicular to the plane of incidence and parallel to the grating grooves. For calculating the detected signal we use a perturbative diffraction theory of a multilayer anisotropic structure. The formalism has been tested by modelling a far-field diffraction experiment. Then we calculate STOM near-field signal above the grating and compare optical images and magneto-optical images.