Optical properties of thick metal nanohole arrays fabricated by electron-beam and nanosphere lithography

Optically thick metallic nanohole structures were fabricated using two different methods – electron‐beam and nanosphere lithography. The nanosphere lithography technique was based on self‐assembling of polystyrene or silica nanospheres (0.560–1.25 μm in diameter) followed by the deposition of a silver film. The holes size and periodicity of the patterns as well as optical properties (transmission and reflection in the Visible–NIR) of the structures were investigated. The extraordinary optical transmission (EOT) was studied experimentally in both structures and it was found to be dependent on the geometrical parameters (holes shape, diameter and periodicity of structures). As the samples were made for long range order, the effect of the defects like missing holes, change of periodicity or variation of the holes shape, were also studied. The experimental results, especially the position of the SPR band in the different nanohole structures, were compared with those found by simulation carried out with 3D FDTD (finite difference time domain). (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)