Dynamic Tuning and Swapping of Electric and Magnetic Dipolar Mie Resonances in High Index Dielectric Particles Dispersed in an Anisotropic Medium

Abstract

AbstractHigh refractive index (n > 2.5) dielectric particles support strong electric and magnetic Mie resonances in the visible region enabling optical properties such as directional scattering, anapole modes, and Fano resonances with applications in nanophotonics. Selenium particles, which possess a high refractive index at optical frequencies, have been synthesized using a controlled approach involving a moderate reduction of selenious acid to obtain particles of the desired size. The extinction spectra from UV–vis spectroscopy in conjunction with theoretical simulations confirm the presence of highly size‐dependent dipole and quadrupole Mie resonances in the visible region. Dynamic tuning of magnetic and electric Mie resonances and swapping of electric and magnetic dipoles are observed in a colloidal dispersion of 250 nm‐sized selenium particles in a nematic liquid crystal due to the anisotropic nature of the latter. Theoretical simulations reveal the presence of unidirectional scattering and photonic‐nanojet formation, attributed to generalized Kerker's effects in nanophotonics and meta‐optics, due to the swapping phenomena leading to the superposition of dipole and quadrupole resonances. The manipulation of Mie resonances in the liquid crystal based colloidal metamaterial has the potential for large‐scale and cost‐effective nanophotonic device applications.