Recent Development in Fiber Optics

DON’T LOOK NOW, but a new low-loss optical fiber?featuring a mirrored core?can conduct an intense stream of laser light that would melt an ordinary fiber.

The photonic bandgap fiber is based on nonmetallic “dielectric mirror” technology developed by Yoel Fink, an MIT assistant professor of material science and engineering (for other Fink research, see “It Reflects Well on You” at www.cio.com/printlinks). The fiber contains a hollow core surrounded by a highly confining reflective surface.

To create the fiber, Fink and his researchers used a pair of materials?arsenic triselenide and polyethersulfone?that have very different optical properties yet soften at the same temperature. The materials are layered in alternating thicknesses and then are fed into a furnace and drawn into a fiber. When stretched, the layers reduce in thickness to micrometer dimensions and create a mirror that confines light to the hollow core. “For the first time, we’re able to make a fiber that has lower losses than the material it’s made of,” says Fink.

Besides providing the foundation for longer distance optical transmission media, the fiber also has several potential industrial and medical applications. On the factory floor, more powerful laser tools would allow workers to quickly and efficiently cut through metal. Surgeons, on the other hand, could use the technology to vaporize dense biological objects, such as kidney stones, that are impervious to existing laser tools. Since the research was partially funded by the Defense Advanced Research Projects Agency, it’s also likely that the military is thinking about using the fiber to shoot high-energy laser bursts at enemy assets.

Fink says he’s already heard from several companies that are interested in using the technology. “We’re working hard at trying to commercialize it,” he notes. “There are probably some roadblocks ahead, since we’re working with previously untried materials, but we haven’t found any yet.”