The role of localized surface plasmon in the THz transmission of metallic rectangular hole arrays

We report on transmission enhancement and suppression in rectangular aperture arrays at terahertz range. Experiments and simulations reveal that transmission maxima and minima of metal film perforated with rectangular apertures arrays are caused by the shape resonance and the interference between surface waves respectively. To further investigate the relative contributions of shape resonance and interference between SPPs, we have examined the density of electrons whose distribution property is identified to the normal component of E-filed which clearly shows that transmission resonance stems from excitation of shape resonance at the edge of the hole. This resonance dominated by cutoff function is responsible for resonance peak at transmitted spectrum. The interference of SPPs originated at surface further enhances the resonances and gives a set of minima in the transmittance spectrum. This study contributes a better understanding of fundamental physics behind the extraordinary transmission of aperture arrays at THz range and provides a simple method for the design of THz devices.