Efficient nonlinear metasurfaces by using multiresonant high-Q plasmonic arrays

We numerically investigate second-harmonic generation from multiresonant plasmonic metasurfaces by designing an array consisting of L-shaped aluminum nanoparticles that simultaneously supports two surface lattice resonances with relatively high quality factors (>100). Using an approach based on the nonlinear discrete-dipole approximation, we predict an over million-fold enhancement of the emitted second-harmonic intensity from a particle at the center of the metasurface compared to an individual particle and estimate that conversion efficiencies of around 10(-5) could be achievable from the surface. Our results are an important step towards making nonlinear metasurfaces practical for nonlinear applications, such as for frequency conversion. (C) 2019 Optical Society of America