Extraordinary optical transmission through incommensurate metal hole arrays in the terahertz region

By using coupled-mode analysis, we investigate numerically the extraordinary optical transmission (EOT) of incommensurate metal hole arrays (IMHAs) in the terahertz region to study how the degree of long-range and short-range orders affect EOT. In IMHAs, the holes of one set of metal hole arrays (MHAs) are regarded to work as impurities to the holes of another set of MHAs. Therefore, the transmittance spectra are expected to be significantly modified from those of the constituent MHAs. It is found that the resonance transmission frequencies of IMHAs almost coincide with those of the composite MHAs despite the fact that the surface waves of each MHA are mutually perturbed strongly due to the presence of short-range disorder. This indicates that the presence of long-range order is essential to establish EOT. These observations allow more flexible design of narrow bandpass filters in the terahertz region.