Facoltà di Ingegneria Civile e Industriale

Adding some asymmetry degree to the geometry of plasmonic metasurfaces can allow for different absorption and/or emission of circular polarizations, important for applications in fields of chiral sensing and flat optics. Emilija Petronijevic, Roberto Li Voti, Concita Sibilia and Alessandro Belardini of ICI SBAI, in collaboration with colleagues from the Nanostructures Group (University of Padova), have demonstrated tuneable, hyperspectral control of the transmitted far-field polarization by means of extrinsic chirality. The studied metasurface was based on only 50 nm of asymmetric gold nanoshells on self-assembled polystyrene nanospheres. The team first measured a great spectral and incident angle tunability of extinction circular dichroism (CD). They then excited the metasurface with linear polarization and performed the hyperspectral Stokes polarimetry on the transmitted field. The study proves that S3 parameter follows the behavior of extinction CD, and that output field position on the Poincaré sphere can be widely controlled by incidence angle and wavelength.

More information:
https://doi.org/10.1039/D3NR06085C