Optical fiber and optical transmission line using the same, and optical transmission system

摘要

The present invention provides an optical fiber forming an optical transmission line for wavelength division multiplexing transmission in a 1.5 mum wavelength band, for example. The cutoff wavelength is set in the range of 1.3 mum or more to 1.4 mum or less, and the chromatic dispersion value at a wavelength of 1.55 mum is set to 4 to 10 ps/nm/km. The effective core area in at least a setup wavelength band of the 1.5 mum wavelength band is set to 40 mum<2 >to 60 mum<2>, and the dispersion slope in the 1.55 mum wavelength band is set to a positive value below 0.035 ps/nm<2>/km. The zero dispersion wavelength is set to 1.43 mum or less, and the bending loss at the diameter of 20 mm in the 1.5 mum wavelength band is set to 5 dB/m or less. The refractive index profile of the optical fiber is designed so that the relative refractive index difference Delta1 of a first glass layer (1) of the innermost layer from a standard layer (6) and the relative refractive index difference Delta3 of a third glass layer (3) at a third-layer position from the innermost from the standard layer (6) are set to positive values, and the relative refractive index difference Delta2 of a second glass layer (2) at a second-layer position from the innermost from the standard layer (6) is set to a negative value.