Method of making fluorine/boron doped silica tubes

摘要

Disclosed is a method of forming a glass tube doped with boron and fluorine. A B2O3-doped tubular porous preform is heated, and a fluorine-containing gas is flowed into its aperture. The temperature is sufficiently high to cause the fluorine-containing gas to decompose and form fluorine which dopes the preform. Also flowed into the aperture is a sufficient amount of BF3 to prevent fluorine from reacting with the B2O3 in the porous preform and forming a B2O3-depleted region near the aperture surface. The particles are then fused to form a fluorine-containing dense glass tube.