Chiral all-dielectric trimer nanoantenna

Chirality is a property of certain molecules, materials or artificial nanostructures, which enables them to interact with the spin angular momentum of an incident light. This provides a different optical response, depending on the incident polarization, which gives rise to chiral optical spectroscopies. However, low-detection limits require an enhanced chiral light-matter interaction. Here, we propose a novel type of resonant chiral optical nanoantenna based on high-index dielectric (Cu2O) spherical nanoparticles arranged in a trimer geometry. We demonstrate both numerically and experimentally that this trimer nanoantenna exhibits resonantly enhanced optical dichroism and light hotspots, which are associated with this geometry. Moreover, we apply near-field optical microscopy to measure the near-field peculiarities of the proposed nanoantenna. The ability of changing the nanoantenna near field scattering by varying the light polarization is shown.