Optical fiber and optical communication system using this optical fiber

Abstract

The present invention resides in an optical fiber able to form an optical transmitting line for wavelength division multiplexing transmission in a wavelength band of 1.5 μm using a Raman amplifier, and an optical communication system using this optical fiber. The optical fiber has an effective core area from 40 μm2 to 60 μm2 in a set wavelength band of at least one portion of a wavelength band of 1.5 μm; a dispersion value from 4 to 10 ps/nm/km at a wavelength of 1.55 μm; a dispersion slope set to a positive value equal to or smaller than 0.04 ps/nm2/km in a wavelength band of 1.55 μm; and a zero dispersion wavelength equal to or smaller than 1.4 μm. Further, a cutoff wavelength is set to be equal to or smaller than 1.5 μm at a length of 2 m, and a bending loss is set to be equal to or smaller than 5 dB/m at a diameter of 20 mm in the wavelength band of 1.5 μm. In a refractive index profile of the optical fiber, for example, a relative refractive index difference Δ1 of a first glass layer as an innermost layer with respect to a reference layer, and a relative refractive index difference Δ3 of the refractive index of a third glass layer as a third layer from an inner side with respect to the reference layer are set to be positive. Further, a relative refractive index difference Δ2 of a second glass layer as a second layer from the inner side with respect to the reference layer is set to be negative.

Dependencies are inferred from the claim text.