PROCESS FOR PRODUCING OPTICAL FIBER PREFORM BY USING MODIFIED CHEMICAL VAPOR DEPOSITION CONTAINING DEHYDRATION AND DESALINATION AND THE OPTICAL FIBER PRODUCED BY THE PROCESS

摘要

PURPOSE: Provided is a process for producing an optical fiber preform by using modified chemical vapor deposition(MCVD) containing dehydration and desalination, which removes hydroxide groups causing light absorption loss and chlorine causing light scattering loss. CONSTITUTION: The process comprises: a sooting process to produce silica soot(12) by injecting reaction gas and oxygen gas into a silicon oxide tube(10) and heating the tube(10) at a sintering temperature or lower, especially 1400-1600deg.C by using a reciprocating torch(14); the dehydration process to remove the hydroxide groups from the silica soot(12) by injecting a mixed gas containing chlorine into the tube(10) and heating at a lower temperature than the sooting process, especially 900-1200deg.C by using the reciprocating torch(14) with a velocity of less than 700mm/min; the desalination process to remove the chlorine from the silica soot(12) by injecting a mixed gas containing oxygen gas into the tube(10) and heating at a higher temperature than the dehydration process and a lower temperature than the sooting process by using the reciprocating torch(14) with a velocity of less than 700mm/min; a sintering process to sinter the silica soot(12) by heating the tube(10) at the sintering temperature or higher, especially 1700deg.C or higher by using the reciprocating torch(14) with a velocity of less than 700mm/min.