Abstract
Transmission spectra of terahertz waves through a two-dimensional array of asymmetric rectangular apertures on super-aligned multi-walled carbon nanotube films were obtained experimentally. In this way, the anisotropic transmission phenomena of carbon nanotube films were observed. For a terahertz wave polarization parallel to the orientation of the carbon nanotubes and along the aperture short axis, sharp resonances were observed and the resonance frequencies coincided well with the surface plasmon polariton theory. In addition, the minima of the transmission spectra were in agreement with the location predicted by the theory of Wood’s anomalies. Furthermore, it was found that the resonance profiles through the carbon nanotube films could be well described by the Fano model.
Highlights
Many groups have carried out theoretical and experimental studies to explore fascinating applications in a variety of fields and to discover the mechanism of this enhanced transmission.[6,7,8,9,10,11]. These studies have demonstrated that a rectangular aperture produces a higher transmission than circular or square apertures with the same area, and they have shown that the enhanced transmission is derived from two different resonant mechanisms: the excitation of surface plasmon polaritons (SPPs) and waveguide mode resonance.[12,13]
At THz frequencies, carbon nanotube films, including single-walled carbon nanotube (SWCNT) films and multi-walled carbon nanotube (MWCNT) films, exhibit metallic characteristics because of the presence of a negative real part in the complex dielectric constant, and they can be regarded as an alternate media for supporting SPPs.[23,24,25]
We focus on the maxima in the transmittance spectra that derive from a resonant interaction between the SPPs and the incident THz wave in the MWCNT film/Si interface
Summary
The surface plasmon-assisted enhanced transmission of light waves through all kinds of periodic subwavelength apertures has attracted extensive attention because of its potential application in the field of subwavelength photonics such as integrated photonic devices, near-field microscopy, and biochemical sensing.[1,2,3,4,5] Many groups have carried out theoretical and experimental studies to explore fascinating applications in a variety of fields and to discover the mechanism of this enhanced transmission.[6,7,8,9,10,11] These studies have demonstrated that a rectangular aperture produces a higher transmission than circular or square apertures with the same area, and they have shown that the enhanced transmission is derived from two different resonant mechanisms: the excitation of surface plasmon polaritons (SPPs) and waveguide mode resonance.[12,13]. We report an experimental study of the transmittance of THz waves through super-aligned MWCNT films patterned by a 2D asymmetric subwavelength rectangular aperture array
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