Electromagnetic Resonance-Modulated Magnetic Emission in Europium-Doped Sub-Micrometer Zirconia Spheres

Light-matter interaction involving magnetic resonance at optical frequencies has recently been extensively investigated for the development of optical metamaterials. Nevertheless, effective manipulation of magnetic dipole transitions at optical frequencies is rarely demonstrated. Herein is reported on an aerosol-spray method for the gram-scale production of all-dielectric europium-doped sub-micrometer zirconia spheres, which support strong magnetic Mie resonances. In contrast to previous structures where magnetic dipole emitters are positioned outside dielectric nanoresonators, this structure offers an unprecedented opportunity for the light emitters to access the strong magnetic field within the dielectric nanoresonator. This unique architecture allows the magnetic emission from the doped europium ions to be effectively manipulated. Moreover, in gold nanosphere-europium-doped zirconia sphere heterostructures, the electric dipole emissions of the europium ions are enhanced strongly by the plasmon resonance of the gold nanospheres, while the magnetic dipole emission is weakly affected, suggesting much weaker interaction between the magnetic dipole transition and the electric resonance. This work demonstrates the feasibility of using all-dielectric nanoresonators for selectively manipulating the magnetic dipole emissions from embedded quantum emitters. In addition, this cost-effective and productive synthesis method opens up many possibilities for the wide use of lanthanide-doped dielectric nanoresonators in the field of nanophotonics.