Real-life tractor beam developed at NYU



A tractor beam is a traveling wave that can transport illuminated material along its length back to its source. By this definition, an optical tweezer [1] is not a tractor beam because of its inherently limited range. Nor is an optical conveyor belt [2, 3], which is created from a standing wave rather than a traveling wave. A one-sided variant of the optical conveyor belt created from coaxial Bessel beams has been demonstrated, but relies on auxiliary forces to achieve retrograde motion [4]. Here, we demonstrate one-sided optical conveyors that act as tractor beams without requiring outside assistance. The same technique we use to project a single optical conveyor also can project arrays of optical conveyors each with independently controlled transport properties.