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.

Figure 1

(a) The incident THz wave form and (b)–(e) THz wave forms (solid lines) transmitted through the metal-hole arrays with several hole diameters $d$. Circles are numerical fittings with the damped harmonic oscillator model for the oscillation components. (f) The Fourier-transformed intensity of the THz wave forms of (b) in the time range after $4\mathrm{ps}$.

Figure 2

The SW lifetime as a function of the hole diameter.

Figure 3

(a) Transmission peak frequencies as a function of the dielectric film thickness attached on the output surfaces of the metal-hole arrays for hole diameters, $d=0.50\mathrm{mm}$ (circle), $0.60\mathrm{mm}$ (triangle), $0.70\mathrm{mm}$ (square), and $0.80\mathrm{mm}$ (cross). (b) The estimated attenuation length of the SW versus the hole diameter.