FORMATION OF COATING ON OPTICAL FIBER

摘要

PURPOSE:To form a film contg. pulverized particles sticking to a film for an optical fiber at a decreased ratio on the fiber by forming said coating on the fiber by a cold wall hot fiber CVD method. CONSTITUTION:The optical fiber 20 is online drawn out through a CVD furnace in such a manner that the fiber is protected by the film deposited by evaporation thereon. The fiber 20 is introduced through a gas isolation chamber 26 in which an inert gas is filled into a reaction chamber 21. The greater part of the chamber 21 is filled with a vacuum bottle 213 for forming a cylindrical channel 214 around the fiber 20. The diameter of the channel 214 is as small as about 3mm, a reactive gas passes near the fiber 20 and reacts efficiently with the fiber in a cold wall hot fiber treatment. The fiber on which the film is formed is taken out through a liquid isolation chamber 27. The undesirable particles deposited on the fiber are removed and the film having no defects and pinholes is formed.