Outside vapor deposition, OVD
One of many variations of vapour deposition technique for fabricating optical fiber. Here an inert rod is layered with core and cladding glass deposits built up on the outside. Once enough layers are in place, the rod is removed and the layers consolidated into a solid preform which can be drawn into fiber. Silicon chloride, SiCl4 and germanium chloride, GeCl4 are oxidised to form silica and germania particles for the deposition.