| 摘要 |
Provided is an optical fiber including: a core at a center thereof; a first cladding adjacent to the core to cover a circumference of the core; and a second cladding adjacent to the first cladding to cover a circumference of the first cladding, where 0.35%≦̸(&Dgr;1−&Dgr;2)≦̸0.65%, 0.30%≦̸&Dgr;1≦̸0.55%, −0.20%≦̸&Dgr;2≦̸−0.05%, 0.22≦̸a/b≦̸0.34, and 4≦̸b√|&Dgr;2|≦̸10 hold, and loss increase resulting when the optical fiber is wound on a mandrel having a diameter of 20 mm is 0.5 dB/turn or smaller at a wavelength of 1550 nm, where &Dgr;1(%) is a specific refractive index difference of a maximum of a refractive index distribution of the core with reference to a refractive index of the second cladding, &Dgr;2(%) is a specific refractive index difference of a minimum of a refractive index distribution of the first cladding with reference to the refractive index of the second cladding, a(μm) is a radius of a boundary between the core and the first cladding with respect to a center of the core, and b(μm) is a radius of a boundary between the first cladding and the second cladding with respect to the center of the core. |
