PRODUCING METHOD OF PREFORM, OPTICAL FIBER ADDED WITH RARE EARTH ELEMENT AND OPTICAL FIBER AMPLIFIER

摘要

PROBLEM TO BE SOLVED: To provide a producing method and the like of a preform where the preform to produce a low-loss optical fiber added with a rare earth element and a P element can be produced efficiently. SOLUTION: The producing method of the preform comprises a first step to deposit glass containing P2O5on the inside wall of a quartz pipe and a second step to introduce a gas containing Cl2in the quartz pipe and to dehydrate the glass containing P2O5by heating the quartz pipe. The preform added with the rare earth element at a core part is produced by performing the first step and the second step alternately and repeatedly. In the producing method of the preform comprising further a third step to deposit glass not containing P2O5on the inside wall of the quartz pipe, it is favorable that the first step, the second step and the third step are performed repeatedly in this order and that glass containing the rare earth element and not containing P2O5is deposited on the inside wall of the quartz pipe in the third step. COPYRIGHT: (C)2009,JPO&INPIT