Optical trapping and assembly of particle clusters using hybrid plasmonic-photonic nanotweezers

Plasmonic nanotweezers are renowned tools for trapping and handling nanoparticles via near-field optical forces. In this work, we investigate the optical trapping of polymer beads using plasmonic nanotweezers integrated on a hybrid photonic-plasmonic chip. A periodic chain of gold nanorods coupled to a silicon photonic waveguide is used to trap single beads as well as self-assembled bead clusters. We evaluate the trapping efficiency and the trapping potential of the nanotweezers by particle tracking and statistical analysis. Vacancy-free clusters composed of four and seven beads are found to be the most stable due to the simultaneous actions of both optical and electrostatic forces. Those results evidence the role of plasmonic nanotweezers for efficient particle assembly and manipulation at the nanoscale in future lab-on-a-chip applications.