Nonlocal Dipole Response of Resonant Particles

Resonant dielectric particles constitute the basis of modern all-dielectric photonics. Many remarkable electromagnetic phenomena are associated with the interplay of electric and magnetic dipole modes of a particle. Usually, the induced dipole moments are assumed to be proportional to an external field. However, it is not obvious a priori that the dipole moments of nonspherical particles should depend only on the fields in the particle center, but not their spatial derivatives. Here, we reveal the nonlocal dipole response of nonspherical particles and interpret the nonlocal corrections to the dipole moments based on symmetry analysis, thus providing new insights into the resonant response of dielectric scatterers.