| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical fiber with which an optical transmission line for wavelength division multiplexing transmission of a wavelength of a 1.5 μm band can be formed. SOLUTION: In at least part of the setting waveband of the wavelength of 1.5 μm band, the cross-sectional area of an effective core is set to be 40 μm<2> to 60 μm<2> , a dispersion value is wavelength 1.55 μm is set to be 4 to 10 ps/nm/km, a dispersion slope in the wavelength of 1.55 μm band is set to be a positive value of 0.035 ps/nm<2> / km or less, a zero dispersion wavelength is set to be 1.43 μm or less, a cutoff wavelength at a length of 2 m is set to be 1.5 μm or less, and bend loss with a diameter of 20 mm is the wavelength of 1.5 μm band is set to be 5 dB/m or less. In the refractive index profile of the optical fiber, the relative index difference Δ1 of the innermost first glass layer 1 with respect to a reference layer 6 and the relative index difference Δ3 of the refractive index of the third glass layer 3 which is the third layer from the inside with respect to the reference layer 6 are set to be positive, and the relative index difference Δ2 of the second glass layer which is the second layer from the inside with respect to the reference layer 6 is set to be negative. |
