Multipole electromagnetic wave scattering by nonspherical high-refractive-index particles

Theoretical approach to the multipole analysis of the extinction and scattering spectra of arbitrary shaped particles with sizes being smaller than wavelengths of incident electromagnetic fields is demonstrated and discussed. The main attention is given to the first multipoles including magnetic quadrupole and electric octupole moments. The method is applied to high-refractive-index nonspherical particles with resonant multipole responses in the microwave range, allowing a decomposition of single extinction (scattering) peaks into their constituent multipole contributions. It is shown by numerical simulations that it is possible to design dielectric particles for which the electric and magnetic multipole resonances are located at the same wavelength, providing new possibilities in control of electromagnetic wave scattering and in metamaterial developments. Firstly this theoretical approach was applied in the optical spectral range for investigation of resonant optical properties of dielectric nanoparticles. However, due to scaling transition, this can be adopted for any electromagnetic spectral range.