Optical and magneto-optical properties of periodic Co double layer film

Co double layer film （CoDLF） consisting of a disk-array layer and an antidot-array layer, both with square order, was investigated. Both the reflectivity and Kerr spectra of CoDLF show anisotropic effects when the azimuthal angle of incident light changes. From the simulation result of surface plasmon polaritons （SPPs）, we attribute the reflectivity minima and Kerr angle maxima in the spectra mainly to the excitation of different diffractional orders＇ SPPs. More interestingly, the Kerr angle changes sign at specific wavelengths. We attribute these phenomena to the excitation of SPPs and localized surface plasmons （LSPs）, and the interaction between them.