Optical magnetism in core-satellite nanostructures excited by vector beams

Core-satellite nanostructures are meta-atom candidates that have strong magnetic modes at optical frequencies and their characterization is important for the development of metamaterials and metafluids. We utilize an electrodynamics-multipolar analysis (ED-MA) method to perform a detailed study of the electric and magnetic modes of a core-satellite nanostructure composed of silver nanoparticles decorated on a dielectric core. In addition to excitation with linearly polarized scalar beams, we utilize radially and azimuthally polarized cylindrical vector beams to selectively excite and enhance the multipolar modes of the core-satellite nanostructure. The refractive index of the dielectric core is altered to better understand the role of retardation in the unique multipolar modes that arise from these vector beam excitations. A more complex Ag-core silica-shell nanostructure decorated with Ag-satellites is also introduced and is shown to diminish the role of magnetic modes and introduce new electric modes selectively excited by a radially polarized beam.