| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a single mode optical fiber that has low initial loss in 1,380 nm band and that can maintain loss at 1,380 nm at a low level even if hydrogen enters by diffusion from the outside. <P>SOLUTION: An optical fiber is formed by fiber-forming from a glass preform in which SiO<SB>2</SB>fine particles are attached to the outside of a quartz rod consisting of a core part 1 and a first clad part 2 so as to form a second clad part 3. The single mode optical fiber is manufactured by setting the ratio D/d between the diameter D of the first clad part 2 and the diameter d of the core part 1 to be 4.0 to 4.8, and keeping the OH concentration of the first and second clad parts 2, 3 at 0.1 ppm or below. Otherwise, the optical fiber is manufactured by setting D/d>4.8 and keeping the OH concentration of the core part 1 and the first clad part 2 at 0.1 ppm or below and that of the second clad part 2 at 100 ppm or below. <P>COPYRIGHT: (C)2003,JPO</p> |
