Surface plasmon generation and light transmission by isolated nanoholes and arrays of nanoholes in thin metal films

Extensive 3-D finite-difference time-domain simulations are carried out to elucidate the nature of surface plasmon polaritons (SPPs) and localized surface plasmon polaritons (LSPs) generated by nanoscale holes in thin metallic films interacting with light. Both isolated nanoholes and square arrays of nanoholes in gold films are considered. For isolated nanoholes, we expand on an earlier discussion of Yin et al. [Appl. Phys. Lett. 85, 467-469 (2004)] on the origins of fringe patterns in the film and the role of near-field scanning optical microscope probe interactions. The associated light transmission of a single nanohole is enhanced when a LSP excitation of the nanohole itself is excited. Periodic arrays of nanoholes exhibit more complex behavior, with light transmission peaks exhibiting distinct minima and maxima that can be very well described with Fano lineshape models. This behavior is correlated with the coupling of SPP Bloch waves and more directly transmitted waves through the holes.