A magneto-optical device including a substrate which is transparent to light in a visible spectrum region and a plurality of ferromagnetic layers arranged thereon, each ferromagnetic layer preferably having a width ranging from 5 to 100 nanometers and a thickness ranging from 0.1 to 5 microns. The ferromagnetic layers are parallel to each other and separated by a distance ranging from 0.2 to 2 microns. The ferromagnetic layers are arranged preferably on the side walls of grooves formed parallel to each other in the transparent substrate.