Abstract: The present invention discloses novel methods for fabricating optical fiber glass preforms which may contain alumina, germania, erbium, or other rare earth metals as dopants. Doping with a higher concentration of alumina enhances the solubility of the erbium, or other rare earth, dopant within the glass and the resultant optical properties of the fiber. However, the addition of an alumina dopant can cause processing difficulties due to the formation of inclusions, such as gas bubble, seeds or crystallite formation, within the glass preform or glass cane. The present invention overcomes these processing difficulties and produces glass preforms or canes that are inclusion-free.

Abstract: A method of making a glass article such as an optical waveguide preform is disclosed. The method comprises drawing a rod in at least two steps. In the first step an elongated, consolidated preform having an aperture therethrough is drawn to a reduced diameter preform. The second step involves drawing the reduced diameter preform into a rod, preferably at a lower temperature than the first step. The method substantially reduces the formation of inclusions in the glass article during drawing.