We demonstrate three-dimensional trapping of low-index particles (20-µm-diameter hollow glass spheres in water) by using a single, strongly focused, stationary dark optical vortex laser beam. The holographically generated vortex, which is similar to a TEM01* mode beam, was also used to trap and form ring patterns of high-index particles.
© 1996 Optical Society of America
K. T. Gahagan and G. A. Swartzlander, Jr., "Optical vortex trapping of particles," Opt. Lett. 21, 827-829 (1996)