Thickness effects on the optical transmission characteristics of small hole arrays on thin gold films.

Transmission characteristics are measured as a function of film thickness on metallic hole array samples which are prepared with varied hole periodicity, size and shape on a silica substrate. We have determined that the transmission efficiency for 130 nm gold thickness is about 40 % less than that of a gold film of 60 nm thickness with the triangular hole structure. The peak positions are also moved significantly as a function of metal thickness due to the coupling of the localized surface plasmon inside the hole. Additionally, under certain conditions of the hole periodicity and size, the transmission efficiency is increased near 750 nm wavelength although the metal thickness is thicker.