Process and devices for the elaboration of preforms for optical fibers

摘要

An apparatus for producing preforms for the production of optical fibers by plasma coating and drawing. A plasma stream produced with the aid of a radio frequency generator is caused to successively pass through three zones in the first of which a mixture of fluidized powders of two materials of appropriate composition is injected and completely vaporized. In the second zone an oxidizing gas having a mixing action is introduced into the deeply cooled stream. The materials and gas react with each other to form microseeds. The powders contain high purity silicon and at least one doping element of the group comprising Al, Ge, B. Ti and Zr. In the third zone an inert gas is introduced and deposition of substance is effected on substrates suitably arranged with respect to the path followed by the plasma stream.