Double nanohole apex-enhanced transmission in metal films

We first present experimental results of enhanced transmission through nanofabricated double-hole arrays in a gold film. An increase in the transmission is observed when the holes are overlapping to produce two apexes, with the transmission more than doubling when the apexes are nearly touching. When the holes are non-overlapping, the transmission maximum drops. The measured spectra through these arrays showed a red-shift in the peak transmission wavelength around 770 nm of nearly 30 nm. These experimental results agree well with our finite-difference time-domain simulations of the double-hole arrays. PACS 78.66.Bz; 42.79.Ag; 42.79.Dj