Programmable Shape-Directed Optical Binding of Plasmonic Nanoparticles

Controlling the organization of plasmonic nanoparticles with optical forces is essential for designing reconfigurable light-responsive materials. However, the role of particle shape in determining optical binding geometries remains unresolved. Here, it is demonstrated that the interplay between gold nanoparticle (Au NP) morphology and optical scattering governs distinct near-field and far-field configurations under optical trapping at a water-glass interface. Au spheres, rods, plates, and decahedra exhibit characteristic orientations and binding behaviors that directly correlate with their shape-dependent scattering responses to linearly polarized near-infrared lasers. By tuning the trapping wavelength, transitions in interparticle spacing, orientation, and collective arrangement are induced across two-, three-, and five-particle systems. These results establish NP shape as a versatile design parameter for programming optical matter, offering new opportunities for dynamic nanoscale assembly, tunable plasmonic interactions, and light-driven metamaterials.