Fano resonances in the optical scattering force upon a high-index dielectric nanoparticle

Abstract

Effects of Fano resonances on optical scattering force upon a high-index dielectric nanoparticle radiated by a plane wave are theoretically investigated. The results demonstrate that five different types of Fano resonances appear in the force and are expressed in a unified way. The magnetic (electric) -based cascades of Fano resonances dominate the peaks of the force. The magnetic (electric) -based conventional Fano resonances and the unconventional Fano resonances suppress the peaks of the force for particular large nanoparticles. All types of Fano resonances together cause broad dips of the force and even a near-zero force effect at particular radii. Finally, by investigating the effects of positive and negative indexes, loss, and gain of the particle on the force, it is shown that negative force arises only as the appropriate gain is introduced in the particle. Our results are important for not only deep understanding of electromagnetic interactions in the optical force but also stable optical manipulation of the dielectric nanoparticle.