ABSTRACT A hexagonal array of silicon (Si) nanodisks is investigated for its ability to control the 1.5‐µm emission of Er 3+ ions via toroidal dipole (TD) resonances. Numerical simulations reveal that the TD resonance forms accessible magnetic hot spots on the nanodisk surface, which enhances the magnetic dipole transitions of Er 3+ ions and directs the emission along the surface normal through the Purcell effect. This effect is experimentally investigated in a silica film containing Er 3+ ‐doped Si nanocrystals formed on a Si nanodisk hexagonal array. The photoluminescence spectra show that the magnetic dipole transition of Er 3+ ions is strongly enhanced by the TD resonance and preferentially directed in the surface‐normal direction. A maximum enhancement factor of 130 is achieved under doubly resonant conditions, where both the excitation and emission wavelengths are simultaneously matched to the corresponding resonances.
Moriasa et al. (2026) studied this question.