Filling the Fiber

Imagine an interstate highway that was permanently hampered by an undriveable ridge running along one or two high-speed lanes. Traffic would suffer, to say the least. That’s roughly the situation facing designers of the world’s fiber-optic information thorough-fares. The manufacturing process that leads to the production of optical fiber has inevitably introduced hydroxyl ions into the ultrapure glass; these absorb light strongly at certain infrared wavelengths, rendering the fibers unacceptably opaque across a big chunk of the spectrum centered at about 1,400 nanometers. Lucent Technologies says it has solved the problem, purging most of the nasty hydroxyl from its fiber-making process. The resulting “AllWave” fiber, due on the market late this year, can boost capacity by carrying optical signals at some 150 individual wavelengths that the older fibers rendered unusable, says Lucent.