Optically controlled circling of particles with a particle-decorated fiber probe

Abstract

With the assistance of a particle-decorated fiber probe, optically controlled circling of particles was demonstrated using 3.14 μm diameter silica particles. The method is based on the temperature gradient and thermal convection when a laser beam of 980 nm (power: 108 mW) is injected into the fibre. Specific currents were created by decorating the tip of the drawn fibre probe with specific geometries of silica particles (diameter: 3.14 μm). Thus, the water was being circulated (convective flow driven by heating), and the particles were drowned into the flow. They were circled anticlockwise along a relatively steady trajectory with a period varying from 3 to 7 s. Once the laser switched off, the particles were immediately stopped. Further experiments show that the circular trajectory can be shifted by moving the fiber probe.