| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of manufacturing a preform rod by which the diffusion of OH group into a core in the manufacture of an optical fiber is prevented. SOLUTION: In the method of manufacturing the preform rod by drawing a core rod having a core part and a 1st clad in a drawing step to manufacture a starting material having a prescribed outside diameter and forming a 2nd clad on the starting material by one of a vapor deposition method, a direct method and a method of jacketing a quartz glass tube, the outside diameter of the starting material is controlled to≥5 mm, the ratio (t/a) of the outside diameter (t) of the 1st clad to the outside diameter (a) of the core part of the core rod is controlled to≥3.8 and the concentration of OH group in the vicinity of the interface between the 1st clad and the 2nd clad is controlled to be up to≤50 ppm. COPYRIGHT: (C)2006,JPO&NCIPI
|
