DSM promotes global standards for fiber coatings

HOUSTON -- DSM Desotech is on something of a crusade, championing the fiber optic industry’s need for standards where ultraviolet-curable fiber optic coatings are concerned. At issue, said Robert Crowell, vice president of fiber optic materials for DSM, is maintaining the quality of fiber optic coatings that alleviate stresses on fiber caused by microbending of the fiber, which can lead to signal distortion and loss.

Two industry forces are creating a potential problem, Crowell said. First, the growth of video and IPTV traffic over fiber has increased usage of the 1550 nanometer and 1625 nanometer wavelengths, “which are particularly sensitive to the microbending phenomenon,” Crowell said. “This is much less an issue for data traffic over fiber.”

Secondly, an influx of new fiber coating manufacturers, many from Asia, has increased the likelihood of lower quality coatings, Crowell said, because there is no global specification to which vendors must work. Already there have been instances where service has been affected by deployment of fiber that had non-optimal coating, he said.

“We’ve already seen this in Asia,” Crowell said. “There have been field failures of cables that led to hundreds of thousands of dollars in cost for replacement of fiber.”

DSM sells its coating technology to fiber optic manufacturers, to be deployed when the glass is originally pulled, Crowell said. There are two layers of coatings: The first primary layer “touches the glass and plays a critical role where microbending is concerned, alleviat[ing] stresses that can distort signals or cause signal loss,” Crowell said. “Microbending can be the result of the temperature at which manufacturing takes place or the speed at which fiber is made.”

A second coating is applied to augment the protection, Crowell said. “This is like painting an object that is the size of human hair,” he said.

At room temperature, fiber that has inadequate coating will perform fine, but in the real world, at lower temperatures, problems can and do arise, Crowell said.

“We have developed a lot of technology to deal with microbending,” Crowell said of DSM, which claims to have about 80% of the global market. “But globally there are no specifications, and it has been hard to get consensus on how to measure this phenomenon. It’s taken for granted, and there is a general lack of awareness, but it is a growing issue in China, and it has the potential to be a growing issue elsewhere, because the Chinese want to export their technology.”

What standards exist today are in-country or regional, Crowell said. DMS is talking about these issues now to raise awareness and build industry consensus. The company recently announced a partnership with Telcordia and plans to begin work with the TIA, as well as approaching the ITU, he said.