LOW-DISPERSION SINGLE-MODE OPTICAL FIBER

Abstract

A low-dispersion single-mode optical fiber includes a core and claddings covering the core. The core has a relative refractive index difference of 0.30-0.65% and a radius of 2.5-4.5 μm. The claddings include first, second, third cladding layers and an outer cladding arranged sequentially from inside to outside. The first cladding layer covers the core, and has a relative refractive index difference of −0.70% to −0.30% and a radius of 4.5-7.5 μm. The second cladding layer covers the first cladding layer, and has a relative refractive index difference of −0.20% to −0.25% and a radius of 7.0-12.0 μm. The third cladding layer covers the second cladding layer, and has a relative refractive index difference of −0.60% to 0.00% and a radius of 10.0-20.0 μm. The outer cladding covers the third cladding layer, and is a layer made of pure silicon dioxide glass.

Claims

1. A low-dispersion single-mode fiber, comprising a core layer and a cladding, wherein the core layer has a relative refractive index difference Δ1 in a range from 0.30% to 0.65% and a radius R1 in a range from 2.5 μm to 4.5 μm, and the cladding is divided into three cladding layers and one outer cladding from inside to outside, wherein a first cladding layer covers the core layer, and has a relative refractive index difference Δ2 in a range from −0.70% to −0.30% and a radius R2 in a range from 4.5 μm to 7.5 μm; a second cladding layer covers the first cladding layer, and has a relative refractive index difference Δ3 in a range from −0.20% to −0.25% and a radius R3 in a range from 7.0 μm to 12.0 μm; a third cladding layer covers the second cladding layer, and has a relative refractive index difference Δ4 in a range from −0.60% to 0.00% and a radius R4 in a range from 10.0 μm to 20.0 μm; and the outer cladding covers the third cladding layer, and is a layer made of pure silicon dioxide glass.

2. The low-dispersion single-mode fiber according to claim 1, wherein the core layer is provided with an inner core layer, wherein the inner core layer is depressed at a central portion thereof and has a relative refractive index difference Δ0 in a range from 0.10% to 0.55% and a radius R0 in a range from 1.0 μm to 2.5 μm.

3. The low-dispersion single-mode fiber according to claim 1, wherein the fiber has a cable cutoff wavelength smaller than 1260 nm.

4. The low-dispersion single-mode fiber according to claim 1, wherein the fiber has a dispersion coefficient in a range from 0.0 ps/nm/km to −18 ps/nm/km at a wavelength of 1260 nm.

5. The low-dispersion single-mode fiber according to claim 1, wherein the fiber has a dispersion coefficient smaller than or equal to 3.5 ps/nm/km at a wavelength of 1380 nm.

6. The low-dispersion single-mode fiber according to claim 1, wherein the fiber has a dispersion coefficient smaller than or equal to 10.0 ps/nm/km at a wavelength of 1460 nm.

7. The low-dispersion single-mode fiber according to claim 1, wherein the fiber has attenuation smaller than or equal to 0.80 dB/km at a waveband ranging from 1260 nm to 1460 nm.

8. The low-dispersion single-mode fiber according to claim 1, wherein the fiber has a bending loss smaller than 0.1 dB when bent into 100 circles with a diameter of 60 mm at a wavelength of 1625 nm.

9. The low-dispersion single-mode fiber according to claim 1, wherein the fiber has a bending loss smaller than 0.25 dB and a bending loss smaller than 1 dB respectively when bent into 10 circles with a diameter of 30 mm at a wavelength of 1550 nm and at a wavelength of 1625 nm, and the fiber has a bending loss smaller than 0.75 dB and a bending loss smaller than 1.5 dB respectively when bent into 1 circle with a diameter of 20 mm at a wavelength of 1550 nm and at a wavelength of 1625 nm.

10. Use of the fiber according to claim 1 as a low-dispersion single-mode fiber in a communication system, wherein the fiber is used for a WDM transmission system working at a waveband ranging from 1260 nm to 1460 nm.

11. The low-dispersion single-mode fiber according to claim 2, wherein the fiber has a dispersion coefficient in a range from 0.0 ps/nm/km to −18 ps/nm/km at a wavelength of 1260 nm.

12. The low-dispersion single-mode fiber according to claim 2, wherein the fiber has a dispersion coefficient smaller than or equal to 3.5 ps/nm/km at a wavelength of 1380 nm.

13. The low-dispersion single-mode fiber according to claim 2, wherein the fiber has a dispersion coefficient smaller than or equal to 10.0 ps/nm/km at a wavelength of 1460 nm.

14. The low-dispersion single-mode fiber according to 2, wherein the fiber has attenuation smaller than or equal to 0.80 dB/km at a waveband ranging from 1260 nm to 1460 nm.

15. The low-dispersion single-mode fiber according to claim 2, wherein the fiber has a bending loss smaller than 0.1 dB when bent into 100 circles with a diameter of 60 mm at a wavelength of 1625 nm.

16. The low-dispersion single-mode fiber according to claim 2, wherein the fiber has a bending loss smaller than 0.25 dB and a bending loss smaller than 1 dB respectively when bent into 10 circles with a diameter of 30 mm at a wavelength of 1550 nm and at a wavelength of 1625 nm, and the fiber has a bending loss smaller than 0.75 dB and a bending loss smaller than 1.5 dB respectively when bent into 1 circle with a diameter of 20 mm at a wavelength of 1550 nm and at a wavelength of 1625 nm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG. 1 schematically shows a refractive index profile of a fiber in Embodiment 1 of the present disclosure.

[0031] FIG. 2 schematically shows a refractive index profile of a fiber in Embodiment 2 of the present disclosure.

[0032] FIG. 3 shows a dispersion curve of a fiber in the present disclosure at a waveband ranging from 1260 nm to 1460 nm and comparisons of the dispersion curve of the fiber with those of an ordinary G.652.D fiber and a non-zero dispersion-shifted single-mode fiber.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] Embodiments are provided below in detail to further supplement and describe the present disclosure.

[0034] Embodiment 1 of the present disclosure is shown in FIG. 1. A fiber includes a core layer and a cladding. The core layer has a relative refractive index difference Δ1 and a radius R1. The cladding is divided into three cladding layers and one outer cladding from inside to outside. A first cladding layer covers the core layer, and has a relative refractive index difference Δ2 and a radius R2. A second cladding layer covers the first cladding layer, and has a relative refractive index difference Δ3 and a radius R3. A third cladding layer covers the second cladding layer, and has a relative refractive index difference Δ4 and a radius R4. The outer cladding covers the third cladding layer, and is a layer made of pure silicon dioxide glass.

[0035] Table 1 shows structural parameters designed for a refractive index profile of the fiber, and Table 2 shows properties of the fiber with the designed structural parameters.

TABLE-US-00001 TABLE 1 Structural parameters designed for a refractive index profile of the fiber. Parameters Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Radius of the core 2.7 3.3 4.5 3.0 3.1 layer R1 (μm) Relative refractive 0.65% 0.45% 0.30% 0.52% 0.54% index of the core layer Δ1 Radius of the first 4.7 5.5 7.0 6.0 5.6 cladding layer R2 (μm) Relative refractive −0.60% −0.70% −0.30% −0.55% −0.42% index of the first cladding layer Δ2 Radius of the second 7.0 12.0 9.0 10.5 10.0 cladding layer R3 (μm) Relative refractive −0.20% 0.00% 0.25% 0.08% 0.14% index of the second cladding layer Δ3 Radius of the third 10.0 20.0 18.0 12.5 14.0 cladding layer R4 (μm) Relative refractive −0.40% −0.60% 0 −0.10% −0.10% index of the third cladding layer Δ4

TABLE-US-00002 TABLE 2 Properties of the fiber with the designed structural parameters. Indexes Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Cable cutoff 1245 1230 1195 1210 1255 wavelength/nm Attenuation @1260 nm 0.450 0.423 0.430 0.463 0.453 Attenuation @1380 nm 0.700 0.602 0.550 0.720 0.430 Attenuation @1460 nm 0.265 0.255 0.245 0.245 0.242 Dispersion coefficient −5.2 −3.7 −7.0 −5.1 −7.7 @1260 nm Dispersion coefficient 2.2 3.2 1.3 1.6 −2.4 @1380 nm Dispersion coefficient 5.6 5.8 5.5 2.5 −0.9 @1460 nm Bending loss when the 0.010 0.015 0.075 0.085 0.080 fiber is bent into 100 circles with a diameter of 60 mm @1625 nm Bending loss when the 0.025 0.030 0.105 0.055 0.032 fiber is bent into 10 circles with a diameter of 30 mm @1550 nm Bending loss when the 0.088 0.099 0.350 0.170 0.125 fiber is bent into 10 circles with a diameter of 30 mm @1625 nm Bending loss when the 0.160 0.075 0.950 0.255 0.144 fiber is bent into 1 circle with a diameter of 20 mm @1550 nm Bending loss when the 0.855 0.532 1.600 0.955 0..642 fiber is bent into 1 circle with a diameter of 20 mm @1625 nm

[0036] Embodiment 2 of the present disclosure is shown in FIG. 2. Embodiment 2 differs from Embodiment 1 only in that, the core layer is provided with an inner core layer. The inner core layer is depressed at a central portion thereof and has a relative refractive index difference Δ0 and a radius R0. Other structures in Embodiment 2 are the same as those in Embodiment 1. By disposing the centrally depressed layer in the core layer of the fiber, an energy distribution inside the fiber is changed from a typical Gaussian distribution to a non-Gaussian distribution, which can ensure a proper increase to a diameter of a mode field of the fiber when a cutoff wavelength is smaller than 1260 nm.

[0037] Table 3 shows structural parameters designed for a refractive index profile of the fiber, and Table 4 shows properties of the fiber under the designed structural parameters.

TABLE-US-00003 TABLE 3 Structural parameters designed for a refractive index profile of the fiber. Parameters Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Radius of the depressed 1.0 1.5 2.5 1.0 1.1 core layer R0 (μm) Relative refractive 0.55% 0.35% 0.20% 0.15% 0.10% index of the depressed core layer Δ0 Radius of the outer core 2.7 3.3 4.5 3.0 3.1 layer R1 (μm) Relative refractive 0.65% 0.45% 0.30% 0.52% 0.54% index of the outer core layer Δ1 Radius of the first 4.7 5.5 7.0 6.0 5.6 cladding layer R2 (μm) Relative refractive −0.60% −0.70% −0.30% −0.55% −0.42% index of the first cladding layer Δ2 Radius of the second 7.0 12.0 9.0 10.5 10.0 cladding layer R3 (μm) Relative refractive −0.20% 0.00% 0.25% 0.08% 0.14% index of the second cladding layer Δ3 Radius of the third 10.0 20.0 18.0 12.5 14.0 cladding layer R4 (μm) Relative refractive −0.40% −0.60% 0 −0.10% −0.10% index of the third cladding layer Δ4

TABLE-US-00004 TABLE 4 Properties of the fiber under the designed structural parameters. Parameters Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Cable cutoff 1240 1210 1190 1215 1220 wavelength/nm Attenuation @1260 nm 0.410 0.433 0.440 0.463 0.473 Attenuation @1380 nm 0.800 0.607 0.450 0.500 0.530 Attenuation @1460 nm 0.278 0.245 0.265 0.246 0.233 Dispersion coefficient −5.4 −6.9 −10.0 −7.4 −14.0 @1260 nm Dispersion coefficient 2.1 3.0 −1.6 −0.9 −11.0 @1380 nm Dispersion coefficient 5.5 5.4 3.1 0.4 −10.5 @1460 nm Bending loss when the 0.025 0.040 0.095 0.090 0.070 fiber is bent into 100 circles with a diameter of 60 mm @1625 nm Bending loss when the 0.045 0.050 0.220 0.085 0.152 fiber is bent into 10 circles with a diameter of 30 mm @1550 nm Bending loss when the 0.108 0.119 0.850 0.370 0.325 fiber is bent into 10 circles with a diameter of 30 mm @1625 nm Bending loss when the 0.360 0.065 0.950 0.355 0.144 fiber is bent into 1 circle with a diameter of 20 mm @1550 nm Bending loss when the 1.055 0.632 1.700 0.955 0..742 fiber is bent into 1 circle with a diameter of 20 mm @1625 nm