Behavior of oblate spheroidal microparticles in a tightly focused optical vortex beam

摘要

We investigated the behavior of an oblate spheroidal polystyrene microparticle trapped in a focused vortex beam when the beam vorticity and polarization were modified. We demonstrated that such particles can be trapped in three dimensions, spin in a circularly polarized beam and an optical vortex beam around the axis parallel to the beam propagation. We compared the immediate frequencies and showed that contribution from the circularly polarized beam is one order of magnitude weaker comparing to the beam angular orbital momentum. Using a phase-only spatial light modulator we generated several vortex beam traps with well-defined parameters. Measuring the rotations of trapped spheroids we observed hydrodynamic phase and frequency locking for certain sets of beam parameters.