Giant distributed optical-field enhancements from Mie-resonant lattice surface modes in dielectric metasurfaces

Abstract

High-index dielectric nanoparticles can support strong localized Mie scattering resonances of both electric- and magnetic-dipole character. Compared to the plasmonic excitations of similar metallic nanostructures, these resonances have the distinct advantage of negligible absorption losses at the expense, however, of significantly reduced optical-field-intensity enhancements. To address this limitation, here we investigate their coherent superposition across neighboring nanoparticles in suitably designed periodic arrays via coupling to lattice surface modes. Numerical simulations show that the resulting excitations can provide giant spatially-averaged field enhancements (distributed across the entire surface of the array) with ultranarrow spectral linewidths, particularly in arrays embedded within a symmetric dielectric environment. These systems are therefore ideally suited for applications involving tailored light-matter interactions with extended-area active layers, such as surface-enhanced sensing, spectroscopy, fluorescence, and photochemistry.