Effect of hole diameter on terahertz surface-wave excitation in metal-hole arrays

The effect of the hole diameter on the surface wave (SW) excited on the metal surface perforated periodically with circular holes has been investigated in the terahertz (THz) region. We find that the SW is localized more strongly on the metal surface with increasing the hole diameter. These results provide the evidence for the existence of the SW-like mode, having properties similar to the surface plasmon polariton in the visible region, even in the THz or lower frequency regions, where metals are regarded as the nearly perfect conductor.