Optical conveyors: A class of active tractor beams

A tractor beam is a traveling wave that can transport illuminated material along its length back to its source.

via Optical conveyors: A class of active tractor beams.


We experimentally demonstrate a class of tractor beams created by coherently superposing coaxial Bessel beams. These optical conveyors have periodic intensity variations along their axes that act as highly effective optical traps for micrometer-scale objects. Varying the Bessel beams’ relative phase shifts the traps axially thereby selectively transports trapped objects either downstream or upstream along the length of the beam. The same methods used to project a single optical conveyor can project arrays of independent optical conveyors, allowing bi-directional transport in three dimensions.