Optical fiber and optical cable

摘要

Provided is an optical fiber that has a small bending loss, can be securely prevented from being fractured due to accidental bending during installation or other operations, and is compliant with the G 652 standard. An optical fiber 1 includes a core 11, a first cladding 12, a second cladding 13, and a third cladding 14. The relative refractive index difference ” 1 of the core 11 is in the range of 0.3% to 0.38%, the relative refractive index difference ” 2 of the first cladding 12 is equal to or smaller than 0%, and the relative refractive index difference ” 3 of the second cladding 13 is in the range of -1.8% to -0.5%. The inner radius r 2 and the outer radius r3 of the second cladding 13 satisfy the expression "0.4r 2 + 10.5 < r 3 < 0.2r 2 + 16", and the inner radius r 2 of the second cladding 13 is equal to or greater than 8 µm. The bending loss at a wavelength of 1550 nm and at a radius of curvature of 7.5 mm is smaller than 0.1 dB/turn, and the bending loss at a wavelength of 1625 nm and at a radius of curvature of 4 mm is greater than 0.1 dB/turn.