Bandgap Tuning in Plasmonic Gratings

We investigate plasmon excitations on thin gold films coated with PMMA grating structures both, in the near field, using a scanning near field optical microscope (SNOM) and in the far field. The dependence of the size and energetic position of a bandgap on structural parameters like grating height and filling factor f is examined. With far field reflection measurements we discover a shift of the bandgap to lower energies with increasing f and we noticed a significant change in the bandgap's size which can be tuned with structural parameters.