Linewidth Narrowing of Surface Plasmon Polaritons Mode in Au Hollow Nanodome Lattices

Au hollow nanodomes arranged in continuous and hierarchical hexagonal lattices support surface plasmon polaritons (SPPs) propagating at air-Au interface. The cross-sectional heights of the both hexagonal nanodome arrays can be altered by a simple thermal treatment. We report that the change of nanodome size leads to a significant linewidth narrowing of SPP modes because of reduced scattering loss. Furthermore, the optimized surface modulation depth is found to be around 100 nm for achieving a longer propagation length of SPP. Quantitative evaluation of the linewidths and integrated intensities of SPP resonances, in correlation with material’s surface morphology, suggests two size regimes where the initial SPP excitation strength varies differently depending on the surface modulation depth.