Abstract

A focused laser beam can be used to two-dimension ally trap and manipulate absorbing particles against a substrate, using radiation pressure. Previously, absorbing particles such as zinc, CuO, and ceramic powder^1-3 have been two-dimensionally trapped by use of focused (LG₀₃ mode) doughnut beams.⁴ In these experiments, the trapped particles rotated as a result of transfer of optical angular momentum associated with the plane-polarized helical wave structure of the doughnut beam. When in addition the light is circularly polarized, the trapped particle will speed up or slow down as compared with the plane-polarized case, depending on the sense of the circular polarization with respect to the sense of the helicity of the wave front.

© 1997 Optical Society of America