| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical fiber having little fluctuations of a transmission loss by temperature change even when an effective core cross-sectional area is large, and to provide an optical fiber cable including the optical fiber.SOLUTION: An optical fiber 20 includes a glass fiber 21 composed of a core and a cladding, a primary resin layer 22 covering the glass fiber 21, and a secondary resin layer 23 covering the primary resin layer 22. The primary resin layer 22 has a glass transition temperature of -40°C or lower. A transmission loss of the optical fiber 20 is denoted byα1 at a wavelength W1 in a range from 1520 nm to 1580 nm in a wound state on a bobbin having a diameter of 150 mm or more and 300 mm or less under the condition of room temperature; a transmission loss of the optical fiber is denoted byα2 at the wavelength W1 under the condition of no lateral pressure to the optical fiber 20; the difference (α1-α2) betweenα1 andα2 at +25°C is 0.003 dB/km or more; and in an environment of -40 to +25°C,α2 is equal toα1-0.005 dB/km or more up toα1. |
