Mapping and Quantifying Electric and Magnetic Dipole Luminescence at the nanoscale

We report on an experimental technique to quantify the relative importance of electric and magnetic dipole luminescence from a single nanosource in structured environments. By attaching a $Eu^{3+}$-doped nanocrystal to a near-field scanning optical microscope tip, we map the branching ratios associated to two electric dipole and one magnetic dipole transitions in three dimensions on a gold stripe. The relative weight of the electric and magnetic radiative local density of states can be recovered quantitatively, based on a multilevel model. This paves the way towards the full electric and magnetic characterization of nanostructures for the control of luminescence at the single emitter level.