Nonlinear self-channeling and beam shaping of magnetostatic waves in ferromagnetic films

Self-channeling and nonlinear beam shaping of magnetostatic waves in thin in-plane magnetized yttrium-iron-garnet films have been observed. Different power levels of a cw signal were launched into a magnetic film using a short microstrip antenna. A Brillouin light scattering system was used to observe the profile of the beams. Self-channeling of the magnetostatic wave beam occurred because of the interplay between the diffraction of the beam and nonlinearity, which leads to self-focusing. This was observed as the input power reached a threshold value equal to a few hundred milliwatts. A discussion of the observations is presented, together with estimates of the parameter ranges.