Tailored Nonlinear Anisotropy in Mie-Resonant Dielectric Oligomers

The field of Mie-resonant nanophotonics has attracted a lot of attention recently due to many promising applications in linear and nonlinear metaoptics. Optically induced magnetic resonances define novel characteristics of isolated high-index dielectric nanoparticles and their oligomers. Here, the orientation-dependent nonlinear frequency generation from dielectric oligomers with different symmetries, being all characterized by isotropic linear response, is demonstrated. The rotational dependence of the third-harmonic signal emitted by the nanoparticle oligomers in accord with their point-group symmetry (e.g., C3 or C4) is observed experimentally, while their linear scattering remains isotropic. The experimental data are in a good agreement with numerical simulations and the symmetry analysis of the nonlinear susceptibility tensor. The results open a new avenue for tailoring nonlinear properties of nanoscale structures.