The observation of OH in annealed optical fiber

We have observed OH in annealed optical fibers. We attribute the OH to silica glass reactions with water and possibly hydrogen, due to the combustion of the fiber's polymer jacket. In our annealing process, fibers were heated from room temperature to about 1200 degrees C. The tiber's optical loss and the polymer jacket's combustion products were measured. Fibers heated with the jacket in place showed an OH absorption at 1390 nm, the amplitude of this absorption peaked at annealing temperatures near 950 degrees C. OH was not detected in fibers annealed with the jacket removed, Fibers held at or above 1200 degrees C began to devitrify. (C) 1998 Elsevier Science B.V. All rights reserved.