Plasmonic Bandgap in 1D Metallic Nanostructured Devices

This research work reports the excitation of surface plasmon polaritons (SPPs) in a 1D grating device in a gold film on glass substrate. Various grating structures have been modelled using finite element analysis (FEA) in comsol RF module. The periodicity in such devices remains constant, whereas slit width is changed for each structure. We have studied the effects of slit width on SPP resonances and formation of the plasmonic bandgap. The trend shows that bandgap energy increases with increasing slit width and reaches a maximum value for slit width nearly equal to half of the periodicity in the grating structure and then decreases which is a new and important observation. The possible reason for this optimum value of the slit width corresponds to the absence of higher plasmonic modes and the sinusoidal nature of the slit.