Anapole-Enhanced Intrinsic Raman Scattering from Silicon Nanodisks

Artikel i vetenskaplig tidskrift, 2018

Enhancement of inelastic light emission processes through resonant excitation usually correlates with enhanced scattering of the excitation light, as is for example typically the case for surface-enhanced fluorescence and Raman scattering from plasmonic nanostructures. Here, we demonstrate an unusual case where a reverse correlation is instead observed, that is, we measure a multifold enhancement of Raman emission along with suppressed elastic scattering. The system enabling this peculiar effect is composed of silicon nanodisks excited in the so-called anapole state, for which electric and toroidal dipoles interfere destructively in the far-field, thereby preventing elastic scattering, while the optical fields in the core of the silicon particles are enhanced, thus, amplifying light-matter interaction and Raman scattering at the Stokes-shifted emission wavelength. Our results demonstrate an unusual relation between resonances in elastic and inelastic scattering from nanostructures and suggest a route toward background-free frequency conversion devices.