Patent ID: 6516125
Filing Date: 2003-02-04
Classification: G02B

Abstract:
A dispersion shifted optical fiber, comprising:a core having a refractive index distribution (ncore); an inner clad surrounding the core and having a refractive index distribution (nclad); and, a silica clad surrounding the inner clad and having a refractive index (nsilica); wherein the core comprises: a first core having a refractive index (n1) that is uniform over its radius (a1); and a second core surrounding the first core and having a refractive index (n2) that is gradually decreased over its radius (a2); and, wherein the inner clad comprises: a first inner clad surrounding the second core and having a refractive index (n3) that is uniform over its radius (a3); and a second inner clad surrounding the first inner clad and having a refractive index (n4) that is uniform over its radius (a4); and, wherein the refractive indices of the first and second cores, the first and second clads and the silica clad satisfy a relationship of n1>n2>n3>n4>nsilica; wherein the optical fiber has dispersion of the 1.5Ëœ3.5 ps/nm-km at a wavelength of 1550 nm, an effective area of 60Ëœ70 &mgr;m2 and a 32 mm&psgr; bending loss of 0.02 dB or less; wherein a radius of the first core (a1), a radius of the second core (a2), a radius of the first inner clad (a3) and a radius of the second inner clad (a4) are 1.0Â±0.15 &mgr;m, 2.3Â±0.15 &mgr;m, 6.5Â±1.5 &mgr;m and 9.0Â±1.0 &mgr;m, respectively; and refractive index differences del1(%), del2(%) and del3(%) are 0.73Â±0.03%, 0.11Â±0.03% and 0.07Â±0.03%, respectively, wherein del1(%) is calculated from the formula (1) below; del2(%) is calculated from the formula (2) below; and del3(%) is calculated from the formula (3) below; del1(%)=[(n1âˆ’nsilica)/nsilica]Ã—100;â€ƒâ€ƒ(1) del2(%)=[(n2âˆ’nsilica)/nsilica]Ã—100;â€ƒâ€ƒ(2) â€ƒdel3(%)=[n3âˆ’nsilica)/nsilica]Ã—100â€ƒâ€ƒ(3).