Photonic binding in silicon-colloid microcavities.

Photonic binding between two identical silicon-colloid-based microcavities is studied by using a generalized multipolar expansion. In contrast with previous works, we focus on low-order cavity modes that resemble low-energy electronic orbitals. For conservative light intensities, the interaction between cavity modes with moderate Q factors produces extremely large particle acceleration values. Optical forces dominate over van der Waals, gravity, and Brownian motion, and they show a binding-antibinding behavior in analogy to electronic binding. As these photonic forces are associated with relatively broad Mie mode resonances and they are not strongly influenced by sample absorption, our study opens a plausible avenue towards manipulation of high-refractive-index colloidal assemblies.