Sapphire Fiber Optics Deliver Higher Transmission Capacity

John Ballato (Clemson University)

Materials scientists and engineers from Clemson University in South Carolina and University of Illinois developed sapphire fibers with greater capacity for high-energy optical transmissions than current silica-based fibers. The team led by John Ballato, director of Clemson’s Center for Optical Materials Science and Engineering Technologies (pictured left), appears online in this week’s issue of Nature Photonics; paid subscription required.

High intensity applications are pushing the limits of traditional silica-based fiber optics, says Ballato. “At high power, the light causes the atoms of the material to vibrate more violently and those vibrations convert some of the light energy into sound energy which restricts the ability of the fiber to carry more power,” Ballato notes. “This, in turn, lessens the amount of light that can travel through the fiber, which limits the amount of information that can be sent for telecommunications uses and power for high-energy laser applications.”

The Clemson team sought a substitute material for silica, particularly a robust, affordable, and easily accessible material with commercial potential. That material needed the capacity to handle the greater power and intensity demands of modern applications, yet still be convertible into an optical fiber.

Ballato and colleagues found that sapphire possesses properties that make it valuable for high power lasers in which the light intensity interacts with sound waves in the glass. “The problem,” says Ballato, “is that sapphire’s crystalline structure is not amenable to making into optical fiber using commercially accepted methods.”

To resolve this problem, the researchers engineered a variation of sapphire with large concentrations of alumina — aluminum oxide — refined from bauxite ore and a feedstock for the metal aluminum. This engineered sapphire made it possible to develop sapphire fiber with the ability to withstand greater transmission intensities than typical commercial fibers and thus be more useful for high-energy applications.

Ballato says the process for creating sapphire fibers can be applied to convert other accessible materials into optical fibers. “This research is paving the way for every day commodities to be imagined for technological uses such as fiber optics,” he adds.

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