PRODUCTION METHOD FOR OPTICAL FIBER PREFORM AND PRODUCTION METHOD FOR OPTICAL FIBER

摘要

PROBLEM TO BE SOLVED: To provide a production method for an optical fiber which can maintain the content of a co-dope elements as designed at first. SOLUTION: The method for producing an optical fiber preform comprises the step of preparing a core glass soot 8 having a central glass soot 5 containing a specified co-dope element and a peripheral glass soot 7 not containing the specified co-dope element by the vapor-phase axial deposition (VAD) method; the step of adding a rare earth element to the core glass soot 8 by immersing it in a rare earth element-containing liquid; the step of drying and sintering the core glass soot 8 to produce a core preform 10; and the step of letting the core preform 10 to pass through a clad preform 11 which comprises a glass component not containing the specified co-dope element and has a hole 11a through which the core preform 10 can pass through and then uniting both the preforms 10 and 11 by heating. COPYRIGHT: (C)2004,JPO