OPTICAL FIBER, OPTICAL FIBER CORD, AND OPTICAL FIBER CABLE

摘要

A trench optical fiber that stably realizes a small transmission loss includes (1) a core extending in an axial direction while containing an axial center of the fiber, the core having a diameter d1 of 7.0 µm to 7.4 µm; (2) a first optical cladding layer surrounding the core and having an outside diameter d2 of 1.67d1 to 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 containing fluorine having a concentration of 0.06 wt% or higher. A relative refractive index difference ”1 of the core with respect to the jacket layer is 0.31 % to 0.37%. A relative refractive index difference ”2 of the first optical cladding layer with respect to the jacket layer is +0.02% or larger and smaller than ”1. A relative refractive index difference ”3 of the second optical cladding layer with respect to the jacket layer is -0.2% or smaller.