PRODUCTION OF CARBON-COATED OPTICAL FIBER

摘要

PURPOSE:To reduce occurrence of soot, improve productivity and obtains high- quality coated optical fiber without deteriorating initial strength by limiting various reaction conditions in producing the carbon-coated optical fiber using acetylene as a raw material gas. CONSTITUTION:In a method for producing hermetically coated optical fiber by passing optical fiber (bare fiber 2) through a reaction vessel 5 during drawing thereof and applying carbon coating thereto in the aforementioned reaction vessel 5 using a thermal chemical vapor deposition (CVD) method, the following conditions are adopted. That is acetylene gas (introduction port 7) is used as a raw material. The acetylene concentration in the reaction vessel 5 is kept at 8-20vol.% and the oxygen concentration is regulated to <=1vol.%. The temperature in the reaction vessel 5 is kept at 100-600 deg.C and the fiber temperature in introduction of the optical fiber 2 into the reaction vessel 5 is regulated to >=600 deg.C.