Rotation of two-dimensional arrays of microparticles trappedby circularly polarized light

We investigate the creation and the rotation of the array of microparticles trapped by circularly polarized light. We find that a smooth rotation requires two-dimensional structure having a rotational symmetry along the light beam axis. We show that it is possible to control smoothly both the rate and the sense of rotation not only by varying the handedness and the power of the incident beam but also by varying the position of the beam focus.