| 摘要 |
PROBLEM TO BE SOLVED: To provide the optical fiber with which an optical transmission line suitable for wavelength division multiplexing transmission can be formed by connecting it to a positive distribution optical fiber. SOLUTION: A second glass layer 2, a third glass layer 3 and a fourth glass layer 4 are provided at the outer peripheral side of a first glass layer 1 in order, and the fourth glass layer 4 is used as a reference layer acting as the reference of a refractive index. A specific refractive index differenceΔ1 of a portion of the first glass layer 1 for the fourth glass layer 4 having the maximum refractive index is set as 1.6% or more and 2.6% or less. A specific refractive index differenceΔ2 of the second glass layer 2 for the fourth glass layer 4 is set as -0.65% or more and -0.4% or less. A specific refractive index differenceΔ3 of the third glass layer 3 for the fourth glass layer 4 is set as 0.15% or more and 0.5% or less. The relation among the outer diameter d1 of the first glass layer 1, the outer diameter d2 of the second glass layer 2 and the outer diameter d3 of the third glass layer 3 is set as 2.5<=(d2/d1)<=3.0 and 1.5<=(d3/d2)<=3.0. |
