Microinstrument gradient-force optical trap

A micromachined fiber-optic trap is presented. The trap consists of four single-mode, 1064-nm optical fibers mounted in a micromachined silicon and glass housing. Micromachining provides the necessary precision to align the four optical fibers so that the outputs have a common intersection. The beam intersection forms a strong three-dimensional gradient-force trap with trapping forces comparable with that of optical tweezers. Characterization of the multibeam fiber trap is illustrated for capture of polystyrene microspheres, computer simulations of the trap stiffness, and experimental determination of the trapping forces. (C) 1999 Optical Society of America.