Identical emission enhancement for arbitrary-orientation magnetic dipole emitters in silicon hollow nanocavity.

Benefiting from low dissipative absorption, dielectric nanoparticles with high-refractive-index have become efficient platforms in producing magnetic dipole resonances and thus harvest functionality in enhancing spontaneous decay rate of optical magnetic dipole emitters, which is also named as magnetic Purcell effect. However, this effect is highly sensitive to emitter orientations, which brings difficulty in practical experiments. Here, we propose an effective method to suppress this orientation sensitivity based on an engineered silicon nanocavity. We will demonstrate that by balancing the resonant wavelengths and emission enhancement for two perpendicularly orientated MD emitters, the whole emission spectrum could be almost orientation-independent, thus accomplishing a completely isotropic magnetic Purcell effect. Further simulations show such effects could survive against a 10 nm spatial deviation of the emitter and will be slightly influenced by the presence of substrate. We anticipate the results of this paper could bring new possibilities in enhancing emission intensity from magnetic dipole transitions in experimental investigations.