Optical fiber base material, its manufacturing method and optical fiber

摘要

A porous glass intermediate body constructed by a core original layer formed as a core portion of an optical fiber, and a first clad original layer formed as a first clad portion of the optical fiber is formed. Thereafter, a transparent glass intermediate body is made by consolidating the porous glass intermediate body within an atmospheric gas with a chlorine-based gas with no fluorine compound. Thereafter, a porous optical fiber base material is made by forming a second clad original layer as a second clad portion of the optical fiber on the circumferential surface of the transparent glass intermediate body. When a porous state is then maintained, the porous optical fiber base material is dehydrated within the atmospheric gas with a chlorine concentration higher than that during the consolidation of the porous glass intermediate body. Thereafter, an optical fiber base material is manufactured by consolidating the porous optical fiber base material within a similar atmospheric gas. The optical fiber is made by wire-drawing this optical fiber base material.