Nano-particles transportation using a holographic multiple-vortex tweezer

Optical vortex tweezers, providing orbital angular momentum to trapped particles, have been successfully demonstrated to sort and deliver micro-particles on a mesoscopic-scale. They used mostly a single vortex, in which a single phase singularity is involved in a wavefront. A multiple-vortex with several phase singularities in a wavefront is potentially capable of controlling several independent optical traps, each with individually specified characteristics, by using a single laser. In this paper, we demonstrate the transport of nano-particles to a specified direction in a mesoscopic field by utilizing three independent vortices with individually specified rotational speed and direction, computer-generated from a single laser beam, for the first time. We call this system a holographic multiple-vortex tweezer. This system, in which many independent vortices with individually specified rotational speed and direction are produced in a mesoscopic field, can thus be adapted to a wide range of applications, including sub-cellular engineering and macromolecular sorting.