Gradient Force Pattern of Gaussian Beam with Helico-Conical Phase Fronts

Vector diffraction theory is employed to investigate the gradient force patterns of the Gaussian beams with helico-conical phase fronts. Results show that the gradient force pattern shape depends principally on topological charge of the phase fronts. The gradient force pattern expands with increasing the parameter of the phase distribution. Therefore, one can change the topological charge or the parameter of the phase mask to construct the tunable optical trap to meet different requirements. Its potential application might include rotational positioning of particles and accumulation of smaller non-symmetric particles towards the focus.