Self-rotation of an assembly of two or more cylindrical objects in optical tweezers: a simple approach for realization of optically driven micromotors

Abstract

We show that an assembly of two or more cylindrical objects rotates by itself when trapped in conventional optical tweezers. The rotational speed and direction of rotation were observed to depend on the asymmetry of the structure, and for a given structure the speed was found to increase linearly with increase in the trapping beam power. A ray optic model was also developed for the assembly of rods. Its predictions on the direction of rotation and the optical torque on the assembly were in qualitative agreement with the experimental observations. Such an assembly of rods may provide a convenient and dynamically reconfigurable approach for optically driven micromotors.