Optical transmission through a subwavelength gold square nanohole array

Abstract

In 1998 Ebbesen and co-workers discovered the extraordinary optical transmission through a subwavelength silver nano hole array. Here we measure the transmittance of a subwavelength gold square nano hole array. We study the transmittance as a function of hole size and as a function of array size. Comparing the results of the 2500 square micrometer array with the 930 square micrometer array, we conclude the array size is an important factor for the transmittance profile. Transmittance of the 2500 square micrometer array follows a clear Fano-profile and has a larger transmittance. For the transmittance dependent on hole size, we can make a distinction between holes that do not support transverse electromagnetic waves, i.e. that are in cutoff, and holes that are not in cutoff. The normalized transmission for arrays that are not in cutoff is not dependent on hole size. This result shines a new light on the extra ordinary transmission.