OPTICAL FIBER, OPTICAL FIBER CORD, AND OPTICAL FIBER CABLE

摘要

A trench-type optical fiber capable of exhibiting consistently low transmission loss is provided with: (1) a core including a fiber axis center, extending in the axial direction, and having a diameter d1 of 7.0-7.4 µm; (2) a first optical cladding layer surrounding the core and having an external diameter d2 of 1.67d1-2.5d1; (3) a second optical cladding layer surrounding the first optical cladding layer; and (4) a jacket layer surrounding the second optical cladding layer and having an F concentration of 0.06 wt%. The specific refractivity difference ?1 of the core with respect to the jacket layer is 0.31-0.37%, the specific refractivity difference ?2 of the first optical cladding layer with respect to the jacket layer ranges from +0.02% to less than ?1, and the specific refractivity difference ?3 of the second optical cladding layer with respect to the jacket layer is equal to or less than -0.2%.