Multipole Evolution and Directional Scattering in Dielectric Nanocubes Embedded in Media

Pavel Terekhov Photonics and Electrooptical Engineering Unit, Ben-Gurion University of the Negev, Beer-Sheva, Israel Ilse Katz Institute for Nanoscale Science & Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel Center for Quantum Information Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel ITMO University, St. Petersburg, Russia

All-dielectric nanophotonics is the rapidly growing area of nanoscience and technology due to dielectric structures’ possibility to manipulate not only with electric component of electromagnetic radiation but also with its magnetic component. To provide deeper understanding of scattering properties of dielectric nanostructures here we use multipole decomposition approach. This approach allows to decompose total scattering cross-section of the nanoparticle to multipole contributions.

We study the multipoles contribution to the light scattering effect when high-index dielectric particle is embedded in media. We found that different multipoles behave in different way as refractive index of media increases. In addition, the electric and magnetic resonances experience different red shift as media changes which lead to their overlapping and total scattering peaks broadening. We investigate spectral evolution of multipoles up to third order: electric dipole moment, magnetic dipole moment, electric quadrupole moment, magnetic quadrupole moment, electric octupole moment and their mutual interaction are considered.

In addition, we explore the far-field scattering effect by analyzing 1) the directional diagrams and 2) electric field distribution inside the particle with respect to refractive index of surrounding medium. Our results prove that changing of electric field distribution inside the particle for high-index surrounding media provides pronounced forward scattering in far-field zone. Our results provide important information for development of nanoantennas and metasurfaces for different dielectric media operating in wide spectral range.