Fabrication of Active Fluoroaluminosilicate Fibers for High-Power Fiber Lasers

An all-vapor phase modified chemical vapor deposition (MCVD) process has been proposed for the fabrication of active-fiber preforms with a fluorine-rich F–Yb2O3–GeO2–Al2O3–SiO2 glass core. The composition of the glass has been shown to differ significantly from that of the vapor–gas mixture because of the formation of GeF4, AlF3, and YbF3, which are volatile at typical MCVD temperatures. We have identified F–Yb2O3–GeO2–Al2O3–SiO2 glass deposition conditions that ensure uniform distributions of the dopants along the length of the preform.