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We experimentally controlled the spectral characteristics of the extraordinary transmissions observed in metal hole arrays by analogy with spoof surface plasmon-polaritons (spoof SPPs). We constructed doubly periodic metal hole arrays. The larger and smaller periodic holes are for inducing extraordinary transmissions and modifying the spoof SPPs' characteristics, respectively. Introducing the smaller holes that surround the larger hole arrays can modify the dispersion curve of the surface waves excited on a structured metal surface analogous to the spoof SPP model, and consequently, the extraordinary transmission peak will show a redshift. [ABSTRACT FROM AUTHOR]

Optical switching of the spectrum and polarization of terahertz radiation from split-ring resonator-loaded photoconductive antennas has been demonstrated. The switching is based on the sensitivity of the resonance of a split-ring resonator on a photoconductive substrate to a change in the capacitance induced by optical pulse irradiation. The spectral and polarization characteristics of the split-ring resonator-loaded photoconductive antennas are discussed in terms of the coupling between the electric dipole induced by the pump laser and the eigenmodes of the split-ring resonators. [ABSTRACT FROM AUTHOR]

We show that the terahertz resonant transmission through metal hole array can be tailored by filling the holes with metamaterials. Experiment and finite difference time domain simulations show this type of resonant transmission to be induced by locally resonant modes, instead of the usual lateral surface grating mode. As the metamaterial's local resonances can be manipulated by varying their geometric configurations, this type of resonant transmission can be tuned over a broad frequency regime that is subwavelength to the array periodicity, with a transmission profile that can also be tailored by the frequency location of the resonance. Such tunability of resonant transmission, with its attendant enhanced local field intensity in the vicinity of the aperture, may provide some potential applications. [ABSTRACT FROM AUTHOR]

Three-dimensional bulk metamaterials that operate in the terahertz (THz) frequency range were fabricated by stacking 100 two-dimensional sheets containing metallic split-ring resonators (SRR) on thin polyethylene terephthalate film substrates. The THz magnetic resonance for the incident magnetic field perpendicular to the plane of the SRR structure was measured. We also investigated the dependence of the magnetic resonant strength on the metal thickness. [ABSTRACT FROM AUTHOR]

We study the effect of a dielectric film attached to the surface of a metal hole array (MHA) on the reflection spectrum in the terahertz (THz) region. The frequency of the reflection dip, attributed to the excitation of surface waves in the vicinity of the MHA surface, shifts to lower frequencies with increasing dielectric film thickness. This resonant characteristic of MHAs can be applied to highly sensitive THz sensing for samples attached to the MHA surface. We also investigate the dependence of the reflection spectrum on the MHA’s thickness and the side to which the dielectric film is attached. [ABSTRACT FROM AUTHOR]