Abstract: An optical fiber splicing method is provided for largely reducing an optical loss in a splice and eliminating a varying outer diameter and bending deformation. This splicing method splices opposing end faces of two optical fibers by fusion, and heats a formed fusion splice to match mode field diameters of the two optical fibers in the fusion splice, wherein the two optical fibers are fixed with an axial tension applied or not applied to the fusion splice, after the formation of the fusion splice, before the fusion splice is heated.

Abstract: The optical fiber includes a center core portion, a side core portion and clad portion, which has a dispersion value of 14-20 ps/nm/km at a wavelength of 1550 nm, a dispersion slope of 0.05-0.08 ps/nm2/km at a wavelength of 1550 nm and a transmission attenuation of 0.2 dB/km or less at a wavelength of 1550 nm, wherein the relative refractive index difference &Dgr;1 between the center core portion and the clad portion is 0.25-0.50%, the relative refractive index difference &Dgr;2 between the side core portion and the clad portion is 0.05-0.30%, an inequality &Dgr;2 <&Dgr;1 is satisfied, the ratio a/b between an outer diameter a of the center core portion and an outer diameter b of the side core portion is 0.3-0.7, and the effective core area Aeff at a wavelength of 1550 nm is 90 &mgr;m2 or larger.

Abstract: The optical fiber includes a center core portion, a side core portion and clad portion, which has a dispersion value of 14-20 ps/nm/km at a wavelength of 1550 nm, a dispersion slope of 0.05-0.08 ps/nm2/km at a wavelength of 1550 nm and a transmission attenuation of 0.2 dB/km or less at a wavelength of 1550 nm, wherein the relative refractive index difference &Dgr;1 between the center core portion and the clad portion is 0.25-0.50%, the relative refractive index difference &Dgr;2 between the side core portion and the clad portion is 0.05-0.30%, an inequality &Dgr;2<&Dgr;1 is satisfied, the ratio a/b between an outer diameter a of the center core portion and an outer diameter b of the side core portion is 0.3-0.7, and the effective core area Aeff at a wavelength of 1550 nm is 90 &mgr;m2 or larger.

Abstract: An optical fiber splicing method is provided for largely reducing an optical loss in a splice and eliminating a varying outer diameter and bending deformation. This splicing method splices opposing end faces of two optical fibers by fusion, and heats a formed fusion splice to match mode field diameters of the two optical fibers in the fusion splice, wherein the two optical fibers are fixed with an axial tension applied or not applied to the fusion splice, after the formation of the fusion splice, before the fusion splice is heated.

Abstract: The optical fiber includes a center core portion, a side core portion and clad portion, which has a dispersion value of 14-20 ps/nm/km at a wavelength of 1550 nm, a dispersion slope of 0.05-0.08 ps/nm2/km at a wavelength of 1550 nm and a transmission attenuation of 0.2 dB/km or less at a wavelength of 1550 nm, wherein the relative refractive index difference &Dgr;1 between the center core portion and the clad portion is 0.25-0.50%, the relative refractive index difference &Dgr;2 between the side core portion and the clad portion is 0.05-0.30%, an inequality &Dgr;2 <&Dgr;1 is satisfied, the ratio a/b between an outer diameter a of the center core portion and an outer diameter b of the side core portion is 0.3-0.7, and the effective core area Aeff at a wavelength of 1550 nm is 90 &mgr;m2 or larger.