Ricerc@Sapienza

Chiral objects do not possess mirror symmetry; they exist in the ¿left¿ and ¿right¿ version, and come in all dimensions, from DNA to chiral galaxies. Chirality governs the interaction of the object with the outside world, defining the properties from molecular toxicity and biological activity, to new degrees of freedom in photonics. Chiral nanostructures are a hot-topic in photonics, as they are able to control the chiro-optical response at the nanoscale. They are designed to differently interact with left and right circularly polarized light (LCP and RCP, respectively); this difference is usually defined as circular dichroism (CD), and can be detected as the differential absorption between LCP and RCP excitations. On the other hand, chiral nanostructures, coupled with emitting layers, can possess CD in the emission, i.e. they can emit light with high degree of circular polarization.
In this proposal we want to experimentally study chiral low-cost metamaterial, coupled with emitting material, for the tunable CD in emission in the visible and near-infrared range. We have previously designed and experimentally studied low-cost chiral plasmonic metamaterials, fabricated in collaboration with the University of Padova (NanoStructures Group); specifically, we characterized chirality in absorption, extinction, and diffraction in the Nonlinear Photonics laboratory at the SBAI Department. Very recently, we numerically proposed chiral emission from these nanostructures by coupling them with emitters. In the present proposal, we optimize design of plasmonic low-cost metasurfaces for the coupling with industrially relevant dye molecules, and fabricate them in Padova. Finally, at the SBAI Department, we construct a new imaging set-up, which allows for the chiral excitation of the nanostructures, and chiral detection of the emission from the coupled system. The ultimate goal of this project is the experimental observation of tunable chiral emission from low-cost metasurfaces.