Exceptional points of all-dielectric nanoresonators

In the recent years, all-dielectric nanophotonics has been showing promising potential for biotechnology, with important progress in the development of efficient all-optical, all-dielectric nanosensing devices overcoming the ohmic losses inherently present in their plasmonic counterparts. In the quest to achieve single molecule sensitivities, a judicious design of the optical response of the nanoantennas is required. Here, we approach this problem from the perspective of non-Hermitian physics and investigate the interaction of two finite nanorods supporting Mie resonances, with the aim of maximizing the frequency detuning induced by a perturbation of the structure. We develop a simple semi-analytical technique to efficiently investigate the coupled system, and we find that Coulomb interactions, together with mutual interference induced by breaking the dimer symmetry, can effectively bring the structure towards a non-Hermitian singularity, an exceptional point, that can potentially increase the sensitivity. The results of this work are expected to lead to novel developments in all-optical single molecule detection, and merge for the first time all-dielectric nanophotonics with exceptional point physics.