Chiral near-field formation with all-dielectric nanoantennas

Engineering of intensity and direction of radiation from a single quantum emitter by means of structuring of their environment at the nanoscale is the cornerstone of modern nanophotonics. Recently discovered systems exhibiting spin-orbit coupling of light are of particular interest in this context. We have demonstrated that asymmetrical excitation of a high-index subwavelength dielectric nanoparticle by a point dipole source located in a notch at its surface can result in the formation of a chiral near field, which is similar to that of a circularly polarized dipole or quadrupole. Using numerical simulations, we have shown that this effect is the result of a higher multipole modes excitation within the nanoparticle. We have applied this effect for unidirectional excitation of dielectric waveguide and surface plasmon-polariton modes. We have achieved the value of front-to-back ratio up to 5.5 for dielectric waveguide and up to 7.5 for the plasmonic one.