Fabrication of heavy metal fluoride glass rods by repetitive high-speed wetting.

Current heavy metal fluoride glass fiber fabrication techniques are mostly based on the casting of preforms. In these techniques the quenching rate of the glass is limited by the square of the radius of the preform, typically 0.5 cm. This results in crystallization and hence enhanced light scatterings, which is the main obstacle presently in achieving very low optical losses (~10 sup -2 db/km). We describe a novel glass (preform core) rod fabrication technique in which the rod is made with axial deposition of thin ( 1 mm) layers of glass. This increases the quenching rate by ~100x compared to the casting techniques. In this new technique a bait rod is rapidly driven into a fluoride glass melt and withdrawn after the tip is wetted with a thin layer of glass. An approximate 10 cm long Zr-Ba- La-Al-Na fluoride rod (0.4 cm diameter) was fabricated with this technique.