Patent ID: 9128237
Filing Date: 2015-09-08
Classification: G02B

Abstract:
1. An optical fiber, comprising: a core portion; and a cladding portion that is formed on an outer periphery of the core portion and has a refractive index lower than a maximum refractive index of the core portion, wherein the core portion comprises a center core portion having the maximum refractive index, and an outer core portion that is formed on an outer periphery of the center core portion and has a refractive index lower than the refractive index of the cladding portion, a relative refractive-index difference Δ1 of the center core portion with respect to the cladding portion is 0.20% to 0.50%, a relative refractive-index difference Δ2 of the outer core portion with respect to the cladding portion is equal to or larger than −0.50% and smaller than 0%, a diameter of the center core portion is 14.00 μm to 19.00 μm, and a ratio of an outer diameter of the outer core portion to the diameter of the center portion is larger than 1.0 and equal to or smaller than 4.0, and characteristics at a wavelength of 1550 nm are an effective core area of a fundamental propagation mode of equal to or larger than 120 μm