Two co-propagating trapping laser beams control optical swarming morphology of gold nanoparticles

Optical trapping of gold nanoparticles at the glass/solution interface gives a single swarming assembly upon irradiating a tightly focused 1064 nm laser. The swarming morphology shows dumbbell-shaped and circular assembling for linearly and circularly polarized laser beams, respectively. Two co-propagating laser beams split from one trapping laser create new morphology, depending on laser polarization and the separation distance of the beams. When the distance is short, the morphology is not much changed. As the distance increased, new morphology appeared where the nanoparticles migrated. The results are well interpreted from the viewpoint of constructive and destructive interference between two beams.(c) 2023 The Japan Society of Applied Physics