Patent ID: 6519402
Filing Date: 2003-02-11
Classification: G02B

Abstract:
A dispersion compensating optical fiber which satisfies the conditions (1) through (4) below:(1) it comprises a core and a cladding layer which is provided at an outer periphery of said core, with said core comprising a central core portion which has a refractive index greater than the refractive index of said cladding, an intermediate core portion which is provided at an outer periphery of said central core portion and which has a refractive index less than the refractive index of said cladding, and a ring core portion which is provided at an outer periphery of said intermediate core portion and which has a refractive index greater than that of said cladding; (2) with radii and relative refractive index differences with respect to a refractive index of said cladding layer of said central core portion, said intermediate core portion and said ring core portion, being termed (a, &Dgr;1), (b, &Dgr;2) and (c, &Dgr;3) respectively, then c is in the range of 6 to 9 &mgr;m, &Dgr;1 is in the range of 1.2% to 1.7%, &Dgr;2 is in the range of âˆ’0.25% to âˆ’0.45%, &Dgr;3 is in the range of 0.2% to 1.1%, b/a is in the range of 2.5 to 4.0, and c/b is in the range of 1.1 to 2.0; (3) the effective area, at a operating wavelength band which is selected within the range of 1.53 &mgr;m to 1.63 &mgr;m, is greater than or equal to 20 &mgr;m2; the bending loss at said operating wavelength band is less than or equal to 20 dB/m, the chromatic dispersion at said operating wavelength band is in the range of âˆ’70 to âˆ’100 ps/nm/km, and it possesses a cutoff wavelength at said operating wavelength band for which single mode propagation is effectively possible; (4) when chromatic dispersion compensation is performed for a single mode optical fiber which has a zero dispersion wavelength which is shorter than said operating wavelength band by employing a length of this dispersion compensating optical fiber which can compensate the chromatic dispersion to zero, the compensation ratio of the dispersion slope is between 80% and 120%.