Transmission characteristics of metallic equilateral triangular nanohole arrays

Transmission spectra through arrays of equilateral triangular nanoapertures show significant transmission increases for most conditions when normalized to the area ratio and compared to those of circular and square apertures. Also, the spectral features of the triangular holes are occasionally shifted when viewed with circular and square arrays of the same periodicity. The authors note that for apertures of the same area, the circumference of a triangular hole is about 75% larger than that of a square hole and about 100% larger than that of a circular hole, indicating that the perimeter region of the apertures may play a larger role in the transmission characteristics of nanoholes than has previously been noted. The authors suggest that the corresponding increase in metal surface area inside the apertures leads to a larger role played by the plasmon which is supported inside the apertures. The authors also suggest that the periodicity of the aperture arrays leads to diffraction effects which also affect the complex spectral characteristics of the transmitted light. Finally, for very small holes (less than 100 nm in diameter), the significance of the triangular shape is diminished. (c) 2006 American Institute of Physics.