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 mu m wavelength band, for example. The cutoff wavelength is set in the range of 1.3 mu m or more to 1.4 mu m or less, and the chromatic dispersion value at a wavelength of 1.55 mu m is set to 4 to 10ps/nm/km. The effective core area in at least a setup wavelength band of the 1.5 mu m wavelength band is set to 40 mu m<2> to 60 mu m<2>, and the dispersion slope in the 1.55 mu m wavelength band is set to a positive value below 0.035ps/nm<2>/km. The zero dispersion wavelength is set to 1.43 mu m or less, and the bending loss at the diameter of 20mm in the 1.5 mu m wavelength band is set to 5dB/m or less. The refractive index profile of the optical fiber is designed so that the relative refractive index difference DELTA 1 of a first glass layer (1) of the innermost layer from a standard layer (6) and the relative refractive index difference DELTA 3 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 DELTA 2 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.