| 摘要 |
PROBLEM TO BE SOLVED: To provide a multicore optical fiber which allows a user to easily specify a location of a defect.SOLUTION: A bare multicore optical fiber 1 includes a plurality of cores 2, 3 and a sheath 4 formed in a manner to cover outer peripheries of the cores 2, 3. In an end cross section obtained by cross-sectionally viewing the bare multicore optical fiber 1 in a direction approximately perpendicular to its axial direction, the cores 2 having the roundness of equal to or less than 2.0 account for equal to or more than 80% and less than 100% of the total number of the cores 2, 3 included in the end cross section, and the cores 3 having the roundness of more than 2.0 are arranged in an area other than the center of the end cross section. |
