Resonant Enhancement of Magneto-Optical Activity Induced by Surface Plasmon Polariton Modes Coupling in 2D Magnetoplasmonic Crystals

Magnetoplasmonic crystals are spatially periodic nanostructured magnetic surfaces combining the features of surface plasmon polariton excitation and magneto-optical tunability. Here we present a comprehensive experimental and theoretical work demonstrating that in magnetoplasmonic crystals the coupling of free space radiation to surface plasmon polariton modes in conjunction with the inherent magneto-optical activity, enable cross-coupling of propagating surface plasmon polariton modes. We have explored the consequences of this unique magnetoplasmonic crystal optical feature by studying the light reflected from a two-dimensional periodic array of cylindrical holes in a ferromagnetic layer illuminated at oblique incidence and magnetized in the sample plane, namely, in the so-called longitudinal Kerr effect geometry. We observe that the magneto-optical spectral response arises from all the excitable surface plasmon polariton modes in the magnetoplasmonic crystal irrespective of the incoming light polarizati...