Wednesday, November 10, 2004

"OPTICS: Viscous entrainment builds nanoscale optics"
The extrusion techniques currently used to manufacture thin optical fibers require an aperture of the same diameter as the created cable, but physicists at the University of Chicago believe they have found a better way. With careful process controls that entrain a viscous liquid, a fiber of any nanoscale size can be manufactured without the need to extrude it through a like-sized aperture, the researchers claim. Both hollow and compound optical fibers can be made in a single step, instead of the two steps necessary today. "Entrainment enables a nonviscous liquid to flow through an aperture into a viscous liquid and pull along some of the viscous material to make a long, thin fiber that is smaller than the aperture," said Wendy Zhang, assistant professor of physics at the University of Chicago. "We believe that with careful control of the processing, you can use viscous entrainment to create [either] submicron hollow waveguides or compound fibers with a core that would have a different index of refraction." By adjusting the speed, pressure and viscosity of such a flow, its diameter can be shrunk without limit.