Photonic clusters formed by dielectric microspheres: Numerical simulations

Abstract

We show through rigorous calculations that small dielectric microspheres can be organized by an incident electromagnetic plane wave into stable geometric configurations, which we call photonic clusters. The longranged optical binding force arises from the multiple scattering between the spheres. A photonic cluster can exhibit a multiplicity of distinct geometries, including quasicrystal-like configurations, with exotic dynamics. Linear stability analysis and dynamical simulations show that the equilibrium configurations can correspond with either stable or a type of quasistable states exhibiting periodic particle motion in the presence of frictional dissipation.

Electrodynamics study of plasmonic bonding and antibonding forces in a bisphere

“…16,17 For nontouching spheres, the MS-MST formalism is highly accurate and rigorous. It takes the full electrodynamics effect into account without making approximations.…”

“…where F ៝ i is the force on the ith sphere͒ that acts to attract or repel the particles from each other, 16,21 with the convention that a positive value of the force indicates repulsion. Following Ref.…”

“…Our electrodynamics calculation shows that owing to the retardation, the optical force oscillates between attraction and repulsion, with a magnitude that scales as ϳD −2 in the far field, just as for two dielectric spheres. 16,21 We next explore the size dependency of the resonant optical force. Figure 4 plots ͉F max ͉ / F single versus r s ͑radius of the particle͒ for two incident frequencies ͑3.25 and 3.5 eV͒ and two polarizations.…”

Emergent properties in optically bound matter

“…At sub-micron scales there are preferred "bond lengths" and angles between nearby particles, which lead to complicated, regular structures [7,8,9]. These can occur even in a uniform background field: the scattered wave from a particle interferes with the background field to produce a spatial intensity modulation.…”

“…These can occur even in a uniform background field: the scattered wave from a particle interferes with the background field to produce a spatial intensity modulation. While the mechanism of longitudinal optical binding in larger particles has received attention from a number of groups [2,10,5,11], lateral binding [7,6] is less well understood. In this letter we describe the results of a simulation based on rigorous scattering theory to describe optical binding, and compare the results with experiment.…”