Plasmonic nanoparticles and metasurfaces to realize Fano spectra at ultraviolet wavelengths

We discuss the possibility to realize sharp Fano scattering signatures in the ultraviolet (UV) range, based on dipolar scattering of nanoparticles. At these frequencies, material losses usually do not allow sharp resonant effects, hindering plasmonic applications based on higher-order multipolar modes, like conventional Fano resonances. We propose to excite degenerate scattering states supported by core-shell nanoparticles made of a sapphire core and an aluminum shell. We predict enhanced, highly confined fields, supporting sharp far-field scattering signatures from single nanoparticles and planar arrays of them. These results may lead to the design of UV filters, photodetectors, sensors, and energy-harvesting devices.