Circular-polarization-dependent mode hybridization and slow light in vertically coupled planar chiral and achiral plasmonic nanostructures

摘要

We numerically studied a square array of plasmonic nanostructures with the unit cell composed of a z-shaped chiral structure and an achiral strip pair. Circular-polarization-dependent mode hybridization between the z-shaped structure's radiant mode and the strip pair's subradiant mode is observed: the resonance amplitudes of two hybrid modes are different for left-handed and right-handed circularly polarized waves, and an electromagnetically induced transparency-like transparency window is obvious for only one circularly polarized wave. Consequently, slow light with small group velocity is only evident for the corresponding polarization state. (C) 2015 Optical Society of America