We present experimental studies of extraordinary terahertz (THz) transmission in subwavelength plasmonic hole arrays patterned on both metals and doped semiconductors. Transmission efficiency higher than unity was achieved when it was normalized to the area occupied by the holes. The effects of hole shape, dielectric function of metals and surrounding media, polarization dependence, and array thickness on the enhanced THz transmission in both metals and plasmonic semiconductors were demonstrated by use of THz time-domain spectroscopy. Extraordinary THz transmission was also realized in metallic arrays having thickness of only one-third of the skin depth. THz surface plasmon resonance has potential applications in THz imaging, biosensing, interconnects, and the development of next generation photoconductive antennas for THz generation and detection.
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