Ran Ling-Ling, Guo Zhong-Yi, Qu Shi-Liang
The rotational motions of the optically trapped microscopic particles by the vortex femtosecond laser beam are investigated in experiment. Black particles can be trapped and rotated by a vortex femtosecond laser beam very effectively because the vortex beam carries orbital angular momentum due to the helical wave-front structure associated with the central phase singularity. Trapped black particles rotate in the vortex beam due to the absorption of the angular momentum transferred from the vortex beam. The rotating directions of the trapped particles can be modulated by reversing the topological charge of the optical vortex in the vortex femtosecond beam. And the rotating speeds of the trapped microscopic particles depend on the topological charges of the vortex tweezer and the used pulse energies greatly.
DOI
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