PREPARING METHOD OF PREFORM FOR OPTIC FIBER

摘要

PURPOSE: A preparing method of preform for an optic fiber is provided to easily prepare multiple mode or single mode fibers with improved performance by minimizing defects like central dip, bump and plateau and deviation at center of refractive index profile. CONSTITUTION: The size of central tube of a preform is reduced without sealing it by heating the preform to a first preform collapsing temperature. The final deposition layer area of a core glass film is etched by injecting etching gas through the central tube at a temperature lower than the first preform collapsing temperature. This preform is collapsed at a second collapsing temperature. Then, the central tube is sealed and a solid rod is obtained.