Terahertz spectroscopic characteristic of metallic slit array

Terahertz (THz) transmission spectrum of metallic slit array is studied by means of terahertz time-domain spectroscopy. Frequency-selective transmission at terahertz frequencies of metallic slit array is shown experimentally and analyzed by numerical simulation. Two kinds of metallic slit array, the rectangular slits and the fractal slits, is investigated respectively. The results illustrate that the obvious transmission enhancement occur for the narrow slits. THz transmission peak has a blue shift until the peak disappear when the slit width becomes larger for the rectangular slit array. The location of THz transmission peak for the fractal slit array is related closely to the first level of line length of fractal structure. In addition, the transmission enhancement of metallic slit array strongly depends on the polarization of terahertz radiation.