Abstract
Although the rotation angle and its spectrum of the magneto-optical Kerr effect are physical quantities determined inherently by the material itself, we found that they can widely be designed by utilizing a one-dimensional photonic crystal with a ferromagnetic defect layer. By suitable choice of the film structure, the rotation angle at a designated narrow wavelength is resonantly enhanced up to as several hundred times larger as ordinary rotation angle of the magnetic. This is originated by the localization of light at the magnetic layer inside the film.