Polarization dependent transmission through asymmetric C-shaped holes

We report that asymmetric c-shaped holes show mode switching between single- and double-resonance frequencies in the terahertz region, when the polarization direction of the incident light is controlled. The number of resonant frequencies is attributed to fundamental shape modes such as circle-, coaxial-, and rectangular-shaped holes activated under each polarization condition. All of these resonant peaks also show a transmission of over 90% with the assistance of the periodically arranged holes. These experimental results are in close agreement with theoretical simulations.