Simultaneously enhanced transmission and artificial optical activity in gold film perforated with chiral hole array

We propose a simple two-dimensional metallic periodic chiral structure (PCS) consisting of a dielectric substrate and a thin gold film perforated with gammadion-shaped chiral hole array, in which the transmittance and artificial optical activity can be simultaneously enhanced. The principle and optical performance of the PCS are demonstrated through the experimental realization of a PCS sample, from numerical design, fabrication, to optical characterization. Good agreement between theory and experiment has been obtained. The PCS sample shows an enhanced transmittance of 53% at wavelength 1168 nm, accompanied nearby by a polarization rotation peak with the effective specific rotatory power up to 10(5) deg/mm. The enhancement mechanism of the dual effect is thoroughly studied by investigating the optical anomalies (i.e., Rayleigh anomalies, surface plasmon polaritons, and localized surface plasmons) in the PCS and their roles in the light-matter interaction. Several light-anomaly coupling regimes have been revealed. The single-layer metallic PCS is relatively easy to realize in optical frequencies by using mature microfabrication techniques such as electron-beam lithography and lift-off technique. The physical insight into the enhancement mechanism provides guidelines to develop more complicated PCS, such as multilayer PCS with metal and dielectric inclusions, which can produce stronger optical activity and better optical performance.