Terahertz transmission properties of quasiperiodic and aperiodic aperture arrays

Recent demonstrations have shown that the transmission through a subwavelength aperture in metal film placed in a periodic lattice or an aperiodic structure is significantly increased relative to a bare aperture. Using terahertz time-domain spectroscopy, we analyze the enhanced transmission properties of aperiodic and corresponding random 2D aperture arrays perforated in metallic films, which include quasicrystals and quasicrystal approximates. We demonstrate that the transmission enhancement phenomenon occurs for aperture arrays having discrete Fourier components in the 2D geometrical structure factor. We further show that the phenomenon is valid for a larger class of 2D aperture array designs that can be tailored to exhibit desired resonances and hence is more general. The inherent relationship between various features observed in the measured time-domain electric field, calculated transmission spectra, and the real and reciprocal space representation of the aperture array is discussed in detail. The results are interpreted in terms of Fano-type interference mechanism. The importance of antiresonance features observed in the transmission spectra is also discussed. (C) 2007 Optical Society of America.