Method of silica optical fiber preform production

摘要

A method is disclosed for the manufacture of optical fiber preforms using plasma enhanced chemical vapor deposition (PECVD). The invention consists of a cylindrical reactor in which material such as flourine-doped silica glass is deposited on a cylindrical silica rod. A furnace for regulating reactor temperature encases the reactor. A microwave generator coupled with a resonator and an H₁₀ waveguide delivers microwave energy to the reactor, producing simultaneously symmetrical excitations in the E₀₁₀ mode and a plasma surface wave in E₀₁ mode located at the surface of the rod. A microwave plasma is scanned along the length of the rod through a slit in the reactor to deposit a homogeneous film of a desired thickness. The benefits of the present invention over the prior art include increased absorption of delivered power, and the ability to uniformly deposit films such as flourine-doped silica on rods with diameters of up to 30-35 mm and thus produce optical fiber preforms with diameters greater than 40 mm.