OPTICAL FIBER, OPTICAL TRANSMISSION SYSTEM, AND METHOD FOR MANUFACTURING OPTICAL FIBER

PROBLEM TO BE SOLVED: To provide an inexpensive and low-loss optical fiber favorably used as an optical transmission line in an optical transmission network.SOLUTION: An optical fiber 1 comprises a central core 11, an optical cladding 12, and a jacket 13. The central core has a relative refractive index difference of 0.2% or more and 0.32% or less with the optical cladding used as a reference, and a refractive index volume of 9% μmor more and 18% μmor less. The jacket has a relative refractive index difference of 0.03% or more and 0.20% or less with the optical cladding used as a reference. The fictive temperature of a glass constituting the central core is 1,400°C to 1,530°C. The stress remaining in the central core is compressive stress. The 2 m fiber cut-off wavelength is 1,300 nm or more. The cut-off wavelength at a fiber length of 100 m is 1,500 nm or less. The effective cross section at a wavelength of 1,550 nm is 110 μmor more. The transmission loss at a wavelength of 1,550 nm is 0.18 dB/km or less.