Enhanced refractive index sensitivity of elevated short-range ordered nanohole arrays in optically thin plasmonic Au films

A simple development of the colloidal lithography technique is demonstrated for fabrication of perforated plasmonic metal films elevated above the substrate surface. The bulk refractive index sensitivity of short-range ordered nanohole arrays in 20 nm thick Au films exhibits an increase of up to 37% due to reduction of substrate effect caused by lifting with a 40 nm silica layer. Analysis of the local electric field distribution suggests that the sensitivity increase is due to revealing of the enhanced field near the holes. (C) 2013 Optical Society of America