COATED OPTICAL FIBER AND METHOD FOR PRODUCING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a coated optical fiber having excellent internal hardenability, excellent in adhesion between a glass optical fiber and a low Young' s modulus layer and capable of being reliably produced even when being drawn at high speed, and to provide a method for producing the optical fiber. SOLUTION: In the coated optical fiber where a primary layer having low Young' s modulus and a secondary layer having high Young's modulus which are made of an ultraviolet curing resin are formed in order on the outer periphery of the glass optical fiber, the primary layer features being composed of plural layers under the following conditions: resins forming the plural layers are obtained by polymerization under a situation that a photoinitiator is added in such a way that an innermost layer has the highest concentration of the photoinitiator and the concentration of the photoinitiator decreases in order as it goes toward the outer layer; or the resins are obtained by polymerization under a situation that only the innermost layer is added with a silane coupling agent.