  Laguerre-Gaussian (LG) beam has orbital angular momentum (OAM). A particle
trapped in an LG beam will rotate about the beam axis, due to the transfer of
OAM. The rotation of the particle is usually in the same direction as that of
the beam OAM. However, we discovere that when the LG beam is strongly focused,
the rotation of the particle and the beam OAM might be in the opposite
direction. This anomalous effect is caused by the negative torque on the
particle exerted by the focused LG beam, which is similar to the optical
pulling force in the linear case. We calculated the scattering force
distribution of a micro-particle trapped in an optical tweezers formed by the
strongly focused LG beam, and showed that there exist stable trajectories of
the particle that controlled by the negative torque. We proposed several
necessary conditions for observing the counter-intuitive trajectories. Our work
reveals that the strongly trapped micro-particle exhibits diversity of motion
patterns.
