Dispersion shifted optical fiber

A dispersion shifted optical fiber comprising a core and cladding provided at an outer periphery of the core, and having a refractive index profile in which the core is provided with a central core portion and a peripheral core portion having a higher refractive index than the central core portion provided at an outer periphery of the central core portion, and

• the cladding has a lower refractive index than the peripheral core portion,
• wherein the core comprises a peripheral core portion, a second ring portion, and a third ring portion provided in that order on the central core portion and when the relative refractive index difference and radius of the central core portion, the peripheral core portion, the second ring portion, and the third core portion are set respectively as (Δ1, r1), (Δ2, r2), (Δ3, r3), and (Δ4, r4) when the cladding is taken as a reference, then the dispersion shifted optical fiber has a refractive index profile in which Δ1 and Δ3 are set as negative values, Δ2 is set as a positive value, and Δ4 is set as 0 or more, and in a used wavelength band selected from 1490 to 1625 nm, the dispersion shifted optical fiber has an effective core area of 50 to 75 μm2, a dispersion slope of 0.03 to 0.06 ps/km/nm2, a chromatic dispersion value of 0.5 to 8 ps/km/nm, a bending loss of 100 dB/m or less, and a cutoff wavelength that provides essentially single mode propagation.

A dispersion shifted optical fiber comprising a core and cladding provided at an outer periphery of the core, and having a refractive index profile in which

• the core is provided with a central core portion and a peripheral core portion having a higher refractive index than the central core portion provided at an outer periphery of the central core portion, and
• the cladding has a lower refractive index than the peripheral core portion,
• wherein the core comprises a peripheral core portion, a second ring portion, and a third ring portion provided in that order on the central core portion and when the relative refractive index difference and radius of the central core portion, the peripheral core portion, the second ring portion, and the third core portion are set respectively as (Δ1, r1), (Δ2, r2), (Δ3, r3), and (Δ4, r4) when the cladding is taken as a reference, then the dispersion shifted optical fiber has a refractive index profile in which Δ1 and Δ3 are set as negative values, Δ2 is set as a positive value, and Δ4 is set as 0 or more, and in a used wavelength band selected from 1490 to 1625 nm, the dispersion shifted optical fiber has an effective core area of 75 to 100 μm2, a dispersion slope of 0.06 to 0.09 ps/km/nm2, a chromatic dispersion value of −8 to +8 ps/km/nm, a bending loss of 100 dB/m or less, and a cutoff wavelength that provides essentially single mode propagation,
• wherein the chromatic dispersion value is a negative value and −0.50%≦Δ1≦−0.20%, 0.65%≦Δ2≦0.85%, −0.50%≦Δ3≦−0.25%, 0.0%≦Δ4≦0.30%, 1.3≦r2/r1≦2.5, 0.5≦(r3−r2)/r1≦5,0.5≦(r4−r3)/r2≦2.0.

A dispersion shifted optical fiber comprising a core and cladding provided at an outer periphery of the core, and having a refractive index profile in which the core is provided with a central core portion and a peripheral core portion having a higher refractive index than the central core portion provided at an outer periphery of the central core portion, and

• the cladding has a lower refractive index than the peripheral core portion,
• wherein the core comprises a peripheral core portion, a second ring portion, and a third ring portion provided in that order on the central core portion and when the relative refractive index difference and radius of the central core portion, the peripheral core portion, the second ring portion, and the third core portion are set respectively as (Δ1, r1), (Δ2, r2), (Δ3, r3), and (Δ4, r4) when the cladding is taken as a reference, then the dispersion shifted optical fiber has a refractive index profile in which Δ1 and Δ3 are set as negative values, Δ2 is set as a positive value, and Δ4 is set as 0 or more, and in a used wavelength band selected from 1490 to 1625 nm, the dispersion shifted optical fiber has an effective core area of 75 to 100 μm2, a dispersion slope of 0.06 to 0.09 ps/km/nm2, a chromatic dispersion value of −8 to +8 ps/km/nm, a bending loss of 100 dB/m or less, and a cutoff wavelength that provides essentially single mode propagation,
• wherein the chromatic dispersion value is a positive value and −0.50%≦Δ1≦−0.05%, 0.65%≦Δ2≦0.85%, −0.50%≦Δ3≦−0.15%, 0.0%≦Δ4≦0.30%, 1.3≦r2/r1≦3.0, 0.5≦(r3−r2)/r1≦2.5, 0.5≦(r4−r3)/r2≦2.0.

A dispersion shifted optical fiber comprising a core and cladding provided at an outer periphery of the core, and having a refractive index profile in which

• the core is provided with a central core portion and a peripheral core portion having a higher refractive index than the central core portion provided at an outer periphery of the central core portion, and
• the cladding has a lower refractive index than the peripheral core portion,
• wherein the core comprises a peripheral core portion, a second ring portion, and a third ring portion provided in that order on the central core portion and when the relative refractive index difference and radius of the central core portion, the peripheral core portion, the second ring portion, and the third core portion are set respectively as (Δ1, r1), (Δ2, r2), (Δ3, r3), and (Δ4, r4) when the cladding is taken as a reference, then the dispersion shifted optical fiber has a refractive index profile in which Δ1 and Δ3 are set as negative values, Δ2 is set as a positive value, and Δ4 is set as 0 or more, and in a used wavelength band selected from 1490 to 1625 nm, the dispersion shifted optical fiber has an effective core area of 100 to 120 μm2, a dispersion slope of 0.08 to 0.10 ps/km/nm2, a chromatic dispersion value of 0.5 to 8 ps/km/nm, a bending loss of 100 db/m or less, and a cutoff wavelength that provides essentially single mode propagation,
• wherein the chromatic dispersion value is a positive value and −0.50%≦Δ1≦−0.25%, 0.65%≦Δ2≦0.75% −0.50%≦Δ3≦−0.25%, 0.0%≦Δ4≦0.30%, 1.3≦r2/r1≦2.5, 0.5≦(r3−r2)≦1.5, 0.5≦(r4−r3)/r2≦2.0.