Probing Spatiotemporal Stability of Optical Matter by Polarization Modulation

Light-driven self-organization of plasmonic nanoparticles via optical binding interactions offers a unique route to assemble mesoscale photonic clusters and chains. However, stability becomes an issue when more nanoparticles are added into the clusters and chains, since the theoretical optical binding strength is inhomogeneous and anisotropic in optical matter systems. Here we study the spatiotemporal stability of optical matter chains self-organized by two to eight ultrauniform gold nanospheres in a linearly polarized optical line trap. Perturbations are introduced into the nanosphere chains by periodically switching the polarization to be either parallel or perpendicular to the orientation of the chains, where the spatial and temporal variation of optical binding strength has been revealed. In addition, we found that the average oscillation amplitude and stability of the particles can be tuned by the frequency of polarization modulation. These results demonstrate a new way to study and improve the stability of optical matter and provide a promising strategy in engineering optical forces at the mesoscale.