Three-dimensional manipulation of a silver nanowire using optical vortex for nanobiotechnology

Recently practical micro/nano devices using nanomaterials such as nanoparticles and nanowires have actively developed in various fields including nanophotonics and nanobiology. Manipulation of nanowires is indispensable for constructing the microdevices. Here we propose and experimentally demonstrates a novel method of three-dimensional optical manipulation of a metallic nanowire using an optical vortex. In our method, a metallic nanowire can be grasped by optical repulsive force and simultaneously rotated by total angular momentum of an optical vortex. In addition, the posture of a metallic nanowire can be horizontally fixed in any direction by high-speed switching of the helical phase shift of an optical vortex. A horizontally aligned nanowire can be also aligned vertically along the optical axis by gradually decreasing the size of an optical vortex focused on a tip of the nanowire. The horizontally or vertically aligned nanowire can be translated to the desired position by moving the stage supporting a sample. The manipulation technique using an optical vortex will be a powerful tool for manipulating and assembling various kinds of nanowires.