Dramatic and Elusive Resonant Lattice Kerker Effect in the Nonlinear Response of Plasmonic Lattices

This article reports an experimental study of a plasmonic metasurface that supports the resonant lattice Kerker effect in the near-infrared wavelength range, manifesting as the suppression of reflection in a narrow spectral range. Such directional scattering is explained by the interaction of electric dipole and quadrupole modes that are simultaneously excited in the meta-atoms and also gives rise to a substantial near-field enhancement. Although in theory this enhancement is anticipated to drastically amplify second-harmonic generation, we show that experimentally this effect is rather elusive due to its extreme sensitivity to experimental conditions. Our experimental results are supported by numerical simulations, and physical insights into the observed effects are provided using a multipole decomposition analysis. This work indicates experimental pitfalls that must be taken into account in the design of nonlinear plasmonic metasurfaces, and suggests how to circumvent them.