Kerker-Driven Janus Scattering in High Index Nanoparticle Metafluid for Naked-Eye Optical Encoding

Strong observation angle dependence of the scattering color is demonstrated in a metafluid in which size-purified silicon nanospheres are dispersed. Theoretical analyses based on Mie theory reveal that the observed macroscopic optical Janus property recognizable by the naked eye is induced by the Kerker effect of individual silicon nanospheres in a metafluid. Evaluation of the observation-angle dependent scattering spectra reveals that the angle dependent color change reaches ∼80° in a hue circle.