Photonic Jackiw-Rebbi states in all-dielectric structures controlled by bianisotropy

Abstract

Electric and magnetic resonances of dielectric particles have recently uncovered a range of exciting applications in light steering at the nanoscale. Breaking of particle inversion symmetry further modifies its electromagnetic response, giving rise to bianisotropy known also as magnetoelectric coupling. Recent studies suggest the crucial role of magnetoelectric coupling in realization of photonic topological metamaterials. To further unmask this fundamental link, we design and test experimentally one-dimensional array composed of dielectric particles with overlapping electric and magnetic resonances and broken mirror symmetry. Flipping over half of the meta-atoms in the array, we observe the emergence of interface states providing photonic realization of the celebrated Jackiw-Rebbi model. We trace the origin of these states to the fact that local modification of particle bianisotropic response affects its effective coupling with the neighboring meta-atoms, which provides a promising avenue to engineer topological states of light.