Overview of Materials and Fabrication Technologies

This chapter provides an overview of materials and fabrication technologies. One of the techniques—vapor-deposition technique—uses oxidation of silicon tetrachloride vapor to produce submicron amorphous silica particles. Other chloride vapors such as germanium tetrachloride and phosphorus oxychloride are used as sources of dopants in the silica. Outside deposition uses flame hydrolysis whereby chloride vapors pass through a propane-oxygen or hydrogen-oxygen flame to produce a “soot” of SiO 2 particles. The vertical axial deposition (VAD) process is a variant of the outside vapor deposition (OVD) method where the core and clad glasses may be deposited either simultaneously or separately. The VAD process forms a cylindrical body using soot, but deposition occurs end-on. A porous soot cylinder is formed without a hole by depositing the core and cladding simultaneously using two torches. The direct nanoparticle deposition (DND) technology is a new fiber manufacturing process, ideally suited for the demanding needs of advanced high-power fiber laser applications. DND provides the flexibility to engineer the glass matrix into which the rare-earth (RE) ions are dissolved. This capability makes it possible to increase the rare-earth concentration without sacrificing the fiber performance with effects resulting from too high local RE ion concentration.