New indirect-light method reliably controls tiny nanomachines
December 2, 2008--A team led by researchers at the Yale School of Engineering & Applied Science (New Haven, CT) has shown that the force of light can be reliably harnessed to drive machines, when the process is scaled to nano-proportions. The research, appearing in the November 27 issue of Nature, demonstrates a marriage of two emerging fields of research--nanophotonics and nanomechanics--that makes possible the extreme miniaturization of optics and mechanics on a silicon chip.
Until now light has been used to maneuver single tiny objects with a focused laser beam--a technique called "optical tweezers." Postdoctoral scientist and lead author, Mo Li noted, "Instead of moving particles with light, now we integrate everything on a chip and move a semiconductor device."
"When researchers talk about optical forces, they are generally referring to the radiation pressure light applies in the direction of the flow of light," said team leader Hong Tang, assistant professor at Yale. "The new force we have investigated actually kicks out to the side of that light flow." While this new optical force was predicted by several theories, the proof required state-of-the-art nanophotonics to confine light with ultra-high intensity within nanoscale photonic wires. The researchers showed that when the concentrated light was guided through a nanoscale mechanical device, significant light force could be generated--enough, in fact, to operate nanoscale machinery on a silicon chip.
The light force was routed in much the same way electronic wires are laid out on today's large-scale integrated circuits. Because light intensity is much higher when it is guided at the nanoscale, they were able to exploit the force. "We calculate that the illumination we harness is a million times stronger than direct sunlight," adds Wolfram Pernice, a Humboldt postdoctoral fellow with Tang.
"We create hundreds of devices on a single chip, and all of them work," says Tang, who attributes this success to a great optical I/O device design provided by their collaborators at the University of Washington.
For the complete story from Yale, visit http://opa.yale.edu/news/article.aspx?id=6245.
--Posted by Gail Overton