Fig. 1: Resonances in subwavelength particles.
From: Metaphotonics with subwavelength dielectric resonators
a–c Mie resonances in dielectric particles: a schematic of a magnetic dipole m* formed by coiled displacement currents j; b optical and SEM image of a resonant silicon nanoparticle; c scattering spectra of a nanoparticle shown in (b). d–f Concept of optical anapole: d Schematic of a toroidal distribution of the displacement currents j1 producing an effective magnetic current coil m* resulting in an effective electric dipole moment j**, which oscillates out of phase with the real electric dipole moment j2; e SEM image of the structure composed of elements supporting the anapole-type distribution of fields; f transmission (solid curve) and reflection (dashed curve) spectra of the structure shown in (e). g–i Friedrich–Wintgen BIC via interfering resonances: g schematic of two decoupled modes associated with displacement currents j1 and j2 generating field oscillating out of phase in the far field zone; h SEM image of a nanodisk supporting quasi-BIC mode; i Q factor of a nanodisk supporting the quasi-BIC mode. b and c are adapted from5; e and f are adapted from6; h and i are adapted from7.
