We demonstrate the coupling of bright and dark surface lattice resonances (SLRs), which are collective Fano resonances in 2D plasmonic crystals. As a result of this coupling, a frequency stop gap in the dispersion relation of SLRs is observed. The different field symmetries of the low- and high-frequency SLR bands lead to pronounced differences in their coupling to free-space radiation. Standing waves of very narrow spectral width compared to localized surface-plasmon resonances are formed at the high-frequency band edge, while subradiant damping onsets at the low-frequency band edge, leading the resonance into darkness. We introduce a coupled-oscillator analog to the plasmonic crystal, which serves to elucidate the physics of the coupled plasmonic resonances and which is used to estimate very high quality factors for SLRs.

dx.doi.org/10.1103/PhysRevX.1.021019
Phys. Rev. X

Rodriguez, S.R.K, Abass, A, Maes, B, Janssen, O.T.A, Vecchi, G, & Gómez Rivas, J. (2011). Coupling bright and dark plasmonic lattice resonances. Phys. Rev. X, 1(2, Article number: 21019), 1–7. doi:10.1103/PhysRevX.1.021019