Tailoring magnetic dipole emission with plasmonic split-ring resonators

We numerically explore the emission behavior of magnetic dipole emitters located next to resonant plasmonic split-ring resonators (SRRs), which are well known for their large magnetic moment at their fundamental resonance in the near infrared. Our results are compared to the situation for electric dipole emitters, where the SRR can be described by solely its electric dipole moment. We show that a similar approach in the case of magnetic dipole emitters is not sufficient, as the symmetry breaking due to the gap has to be taken into account. We demonstrate how retardation between the emitter and the SRR can be used as an additional degree of freedom to manipulate the emission spectrum. Our concept will pave the road towards efficient plasmonic antennas for magnetic dipole emitters.