Observation of three-dimensional optical stacking of microparticles using a single Laguerre-Gaussian beam

The ability of Laguerre-Gaussian (LG) beams to trap, levitate, and stack multiple particles in an orderly fashion around the intensity rings of the LG beam was described. Such trapping was demonstrated by defocusing the LG beam such that the focus point of the LG beam was below the coverslip. It was shown that a focal point of the LG beam was able to provide a more stable trap than that of intensity annular rings. The analysis showed that the technique of stacking could be extended to optical fields of designed shaped such that the stacking microparticles could be organized according to the shaped of the beam intensity.