We report a physical explanation for the phenomenon wherein the backscattering of light by dielectric particles of sizes between 100 and is enhanced by 7–11 orders of magnitude. The phenomenon involves complex composite interactions between a dielectric microsphere and a nanoparticle positioned in close proximity to the microsphere. We provide both analytical and perturbation analyses that show that the enhanced backscattering intensity of a nanoparticle is proportional to the third power of its size parameter. Potential applications of this phenomenon include visible-light detection, characterization, and manipulation of particles as small as a few nanometers.
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