High-Q quadrupolar plasmonic lattice resonances in horizontal metal–insulator–metal gratings

We propose a plasmonic platform for achieving out-of-plane quadrupolar plasmonic surface lattice resonances (SLRs) with large quality factors. The proposed platform is composed of a horizontal metal–insulator–metal (MIM) grating embedded in a homogeneous dielectric environment. Numerical results based on rigorous coupled-wave analysis show that under oblique incidences, high- Q out-of-plane quadrupolar SLRs can be excited at wavelengths of 1242...