Helical wave-front laser beam generated with a microelectromechanical systems (MEMS)-based device

We report a novel helical wave-front laser beam generator based on microelectromechanical systems (MEMS) technology. The device consists of a circular array of micromirrors; each can be electrostatically actuated to move perpendicular to the substrate to modulate the phase of an incident laser beam. A prototype device has been developed using the polysilicon multiuser MEMS processes. The ability of the device to transform a plane wave into an l=3 helical wave-front laser beam has been experimentally demonstrated. Additionally, the device is faster by two orders of magnitude or more than conventional liquid crystal spatial light modulators. In combination with a rapid optical beam steering system, the proposed device might provide new capabilities for fast-scanned optical tweezer arrays, allowing them to combine optical vortices and conventional traps together to trap, guide, and rotate a wide variety of particles.