An interacting dipole model to explore broadband transverse optical binding

The demonstration of optical binding of micro-particles placed in intense optical fields has resulted in unique and exciting prospects for studying new forms of condensed matter. The ability to tailor optical fields in the spatial and temporal domains elicits the possibility of creating novel condensed matter with the structure controlled by tailoring the optical field. Here, we theoretically calculate the transverse optical binding forces for nanoparticles within monochromatic and broadband optical fields. We demonstrate the decrease in amplitude of the optical binding forces for broadband fields as a function of inter-particle separation and attribute the effect to the averaging effect of spectrally dependent optical forces. We also examine multiple particle optically bound systems and use the interacting dipole method to find self-organized positions for six and ten particles illuminated by a monochromatic plane wave.