LAUSR

Using simple and inexpensive nanosphere lithography, we produce large, centimeter-squared sized thin golden films patterned with a hexagonal array of nanoapertures with controllable dimensions on the order of 100–300 nm, spaced by a 350–375 nm pitch distance. The optical transmission spectra of our samples are dominated by the resonant plasmonic features in the spectral range 500–700 nm, caused by the nanostructure in the film. At the same time, the transmission at terahertz (THz) radiation is as high as ∼10% and is spectrally flat. Our measurements are in agreement with finite difference time domain simulations. Such thin metal hole array films allow for very efficient injection of optical energy, while at the same time maintaining reasonably high transparency of THz waves. These structures can be used in any application combining strong optical sensitivity and THz transparency, in optical biomolecular sensing, or as optically transparent electrodes.