Experimental study of the interaction between localized and propagating surface plasmons.

The interaction between localized and propagating surface plasmons is investigated in a structure consisting of a two-dimensional periodic gold nanoparticle array, an SiO2 spacer, and a gold film. The resonance wavelengths of the two types of surface plasmons supported by the structure are tailored by changing the gold nanoparticle size and the array period. An anticrossing of the resonance positions is observed in the reflection spectra, demonstrating the strong coupling between localized and propagating surface plasmons.