Non-radiating anapole state in dielectric nanostructures and metamaterials

Abstract Plasmonic metamaterials and all-dielectric metamaterials, based on metallic or dielectric nanostructures, can concentrate light into subwavelength regions and manipulate light at nanometre length scales through the collective oscillation of free electrons in a metal (plasmon resonances) or from the oscillation of polarization charges and the circular displacement current that are excited inside dielectric material (Mie resonances). However, the plasmonic nanostructures undergo large Joule losses and inevitable thermal heating. The all-dielectric metamaterials may overcome the critical issue of heat dissipation and could bridge the gap between fundamental nanoscience and devices. The dielectric resonance elements can be excited by electric and magnetic Mie resonances, and these Mie-type resonance modes can couple or interfere with each other or with other optical modes. Specially, while the radiation of the electric dipole and toroidal dipole modes are similar and in opposite phases, the total scattering cancelation in the far field is reduced to zero, i.e. non-radiating anapole dark state is generated. By manipulating of interaction of multipolar resonances in structured materials, the new field of all-dielectric resonant meta-optics has achieved rapid development. Here, we review the recent development of anapole dark state in dielectric metamaterials, including excitation, probing, coupling, and manipulation. We further discuss the potential applications of anapole state in nanophotonics. This review provides new insights into anapole physics, discussing its excitation, probing, coupling, manipulation, and potential applications in dielectric metamaterials, as well as hybrid and metal structures. We highlight the unique advantages of dielectric platforms, particularly their low-loss characteristics, and explore how these properties enable advanced control of light at the nanoscale.