Plasmonic nature of extreme optical chirality of subwavelength hole arrays

We study optical properties of subwavelength arrays of 3D-chiral metal holes exhibiting extreme circular dichroism and optical activity. The nanoscale shape features resolved by atomic force microscopy were processed with the developed AFM-to-FDTD data pipeline for reconstruction, averaging and preparation of the hole shape for FDTD simulations. The simulation results point unambiguously at the chiral localized plasmon resonance as the cause of the extreme optical chirality.