Bending-insensitive, radiation-resistant single-mode optical fiber

Abstract

The present invention relates to the field of single-mode optical fibers and discloses a bending-insensitive, radiation-resistant single-mode optical fiber, sequentially including from inside to outside: a core, inner claddings, and an outer cladding, all made from a quartz material. The inner claddings comprise, from inside to outside, a first fluorine-doped inner cladding and a second fluorine-doped inner cladding. The core and the first fluorine-doped inner cladding are not doped with germanium. The respective concentrations of other metal impurities and phosphorus are less than 0.1 ppm. By mass percent, the core has a fluorine dopant content of 0-0.45% and a chlorine content of 0.01-0.10%; the first fluorine-doped inner cladding has a fluorine concentration of 1.00-1.55%; and the second fluorine-doped inner cladding has a fluorine concentration of 3.03-5.00%.

Claims

1. A bending-insensitive, radiation-resistant single-mode optical fiber, sequentially comprising, from inside to outside, a core, inner claddings, and an outer cladding; wherein the core, the inner claddings and the outer cladding are all made from a quartz material; wherein the inner claddings comprise, from inside to outside, a first fluorine-doped inner cladding, and a second fluorine-doped inner cladding; the core and the first fluorine-doped inner cladding are not doped with germanium, and a first concentration of other metal impurities and a second concentration of phosphorus are less than 0.1 ppm: by mass percent, the core has a fluorine dopant content of 0-0.45% and a chlorine content of 0.01-0.10%; the first fluorine-doped inner cladding has a fluorine concentration of 1.00-1.55%; and the second fluorine-doped inner cladding has a fluorine concentration of 3.03-5.00%; wherein a first maximum relative refractive index difference 1.sub.max between the core and the first fluorine-doped inner cladding is 0.30%, a second maximum relative refractive index difference 2.sub.max between the first fluorine-doped inner cladding and the second fluorine-doped inner cladding is 0.61%, and a third maximum relative refractive index difference 3.sub.max between the second fluorine-doped inner cladding and the outer cladding is 0.91%.

2. The bending-insensitive, radiation-resistant single-mode optical fiber according to claim 1, wherein the single-mode optical fiber has an attenuation coefficient of 0.322 dB/km at a wavelength of 1310 nm, an attenuation coefficient of 0.185 dB/km at a wavelength of 1550 nm and an attenuation coefficient of 0.186 dB/km at a wavelength of 1625 nm.

3. The bending-insensitive, radiation-resistant single-mode optical fiber according to claim 1, wherein the single-mode optical fiber has a bending loss of 0.11 dB at a wavelength of 1550 nm and a bending loss of 0.21 dB at a wavelength of 1625 nm when wound by one circle under a bending diameter of 10 mm.

4. The bending-insensitive, radiation-resistant single-mode optical fiber according to claim 1, wherein a first radius R1 of the core is 3.9-4.3 m, a second radius R2 of the first fluorine-doped inner cladding is 5-34 m, and a third radius R3 of the second fluorine-doped inner cladding is 22-48 m.

5. The bending-insensitive, radiation-resistant single-mode optical fiber according to claim 4, wherein the first radius R1 of the core is 4 m, the second radius R2 of the first fluorine-doped inner cladding is 30 m, and the third radius R3 of the second fluorine-doped inner cladding is 46 m.

6. The bending-insensitive, radiation-resistant single-mode optical fiber according to claim 1, wherein under a gamma radiation dose of 2000 kGy, the single-mode optical fiber has a radiation additional loss below 14.8 dB/km at a wavelength of 1310 nm.

7. The bending-insensitive, radiation-resistant single-mode optical fiber according to claim 1, wherein the single-mode optical fiber is clad with an optical fiber coating prepared from one or two of high-temperature resistant acrylic resin, silicone rubber, polyimide, carbon and metal.

8. A bending-insensitive, radiation-resistant single-mode optical fiber, sequentially comprising, from inside to outside, a core, inner claddings, and an outer cladding; wherein the core, the inner claddings and the outer cladding are all made from a quartz material; wherein the inner claddings comprise, from inside to outside, a first fluorine-doped inner cladding, and a second fluorine-doped inner cladding; the core and the first fluorine-doped inner cladding are not doped with germanium, and a first concentration of other metal impurities and a second concentration of phosphorus are less than 0.1 ppm: by mass percent, the core has a fluorine dopant content of 0-0.45% and a chlorine content of 0.01-0.10%; the first fluorine-doped inner cladding has a fluorine concentration of 1.00-1.55%; and the second fluorine-doped inner cladding has a fluorine concentration of 3.03-5.00%; wherein, a first maximum relative refractive index difference 1.sub.max between the core and the first fluorine-doped inner cladding is 0.28%, a second maximum relative refractive index difference 2.sub.max between the first fluorine-doped inner cladding and the second fluorine-doped inner cladding is 0.7%, and a third maximum relative refractive index difference 3.sub.max between the second fluorine-doped inner cladding and the outer cladding is 0.28%; or a first maximum relative refractive index difference 1.sub.max between the core and the first fluorine-doped inner cladding is 0.28%, a second maximum relative refractive index difference 2.sub.max between the first fluorine-doped inner cladding and the second fluorine-doped inner cladding is 0.4%, and a third maximum relative refractive index difference 3.sub.max between the second fluorine-doped inner cladding and the outer cladding is 0.28%; or a first maximum relative refractive index difference 1.sub.max between the core and the first fluorine-doped inner cladding is 0.28%, a second maximum relative refractive index difference 2.sub.max between the first fluorine-doped inner cladding and the second fluorine-doped inner cladding is 0.5%, and a third maximum relative refractive index difference 3.sub.max between the second fluorine-doped inner cladding and the outer cladding is 0.28%; or a first maximum relative refractive index difference 1.sub.max between the core and the first fluorine-doped inner cladding is 0.28%, a second maximum relative refractive index difference 2.sub.max between the first fluorine-doped inner cladding and the second fluorine-doped inner cladding is 0.5%, and a third maximum relative refractive index difference 3.sub.max between the second fluorine-doped inner cladding and the outer cladding is 0.78%; or a first maximum relative refractive index difference 1.sub.max between the core and the first fluorine-doped inner cladding is 0.133%, a second maximum relative refractive index difference 2.sub.max between the first fluorine-doped inner cladding and the second fluorine-doped inner cladding is 0.96%, a the third maximum relative refractive index difference 3.sub.max between the second fluorine-doped inner cladding and the outer cladding is 1.093%.

9. The bending-insensitive, radiation-resistant single-mode optical fiber according to claim 8, wherein the single-mode optical fiber has an attenuation coefficient of 0.322 dB/km at a wavelength of 1310 nm, an attenuation coefficient of 0.185 dB/km at a wavelength of 1550 nm and an attenuation coefficient of 0.186 dB/km at a wavelength of 1625 nm.

10. The bending-insensitive, radiation-resistant single-mode optical fiber according to claim 8, wherein the single-mode optical fiber has a bending loss of 0.11 dB at a wavelength of 1550 nm and a bending loss of 0.21 dB at a wavelength of 1625 nm when wound by one circle under a bending diameter of 10 mm.

11. The bending-insensitive, radiation-resistant single-mode optical fiber according to claim 8, wherein a first radius R1 of the core is 3.9-4.3 m, a second radius R2 of the first fluorine-doped inner cladding is 5-34 m, and a third radius R3 of the second fluorine-doped inner cladding is 22-48 m.

12. The bending-insensitive, radiation-resistant single-mode optical fiber according to claim 11, wherein the first radius R1 of the core is 4 m, the second radius R2 of the first fluorine-doped inner cladding is 30 m, and the third radius R3 of the second fluorine-doped inner cladding is 46 m.

13. The bending-insensitive, radiation-resistant single-mode optical fiber according to claim 8, wherein under a gamma radiation dose of 2000 kGy, the single-mode optical fiber has a radiation additional loss below 14.8 dB/km at a wavelength of 1310 nm.

14. The bending-insensitive, radiation-resistant single-mode optical fiber according to claim 8, wherein the single-mode optical fiber is clad with an optical fiber coating prepared from one or two of high-temperature resistant acrylic resin, silicone rubber, polyimide, carbon and metal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a top view of a bending-insensitive, radiation-resistant single-mode optical fiber in the embodiment of the present invention;

(2) FIG. 2 is a sectional view of the bending-insensitive, radiation-resistant single-mode optical fiber in the embodiment of the present invention.

(3) Marks of the Reference Signs: 1core, 2first fluorine-doped inner cladding, 3second fluorine-doped inner cladding, 4outer cladding

DETAILED DESCRIPTION

(4) A further detailed description of the present invention is given with the accompanying drawings and specific embodiment as follows.

(5) As is shown in FIG. 1, the embodiment of the present invention provides a bending-insensitive, radiation-resistant single-mode optical fiber. The bending-insensitive, radiation-resistant single-mode optical fiber sequentially comprises, from inside to outside, a core 1, inner claddings and an outer cladding 4 which are all made from a quartz material, wherein the inner claddings comprise, from inside to outside, a first fluorine-doped inner cladding 2 and a second fluorine-doped inner cladding 3, the core 1 and the first fluorine-doped inner cladding 2 are not doped with germanium (instrumental analysis shows that the germanium concentration is less than 1 ppm), and respective concentrations of other metal impurities and phosphorus are less than 0.1 ppm; by mass percent, the core 1 has a fluorine dopant content of 0-0.45% and a chlorine content of 0.01-0.10%: the first fluorine-doped inner cladding 2 has a fluorine concentration of 1.00-1.55%; and the second fluorine-doped inner cladding 3 has a fluorine concentration of 3.03-5.00%.

(6) As is shown in FIG. 1, the core 1 is located at the center of the cross section of the optical fiber and is the main light guiding region of the optical fiber: the core 1 is sequentially clad with the first fluorine-doped inner cladding 2 and the second fluorine-doped inner cladding 3, and the first fluorine-doped inner cladding 2 and the second fluorine-doped inner cladding 3 are annular regions, doped with fluorine, on the cross section of the optical fiber; and the second fluorine-doped inner cladding 3 is clad with the outer cladding 4. The radius R1 of the core 1 is 3.9-4.3 m, the radius R2 of the first fluorine-doped inner cladding 2 is 5-34 m, the radius R3 of the second fluorine-doped inner cladding 3 is 22-48 m, and the radius R4 of the outer cladding 4 is 60.5-64.5 m.

(7) The maximum relative refractive index difference 1.sub.max between the core 1 and the first fluorine-doped inner cladding 2 is 0.13%-0.30%; the maximum relative refractive index difference 2.sub.max between the first fluorine-doped inner cladding 2 and the second fluorine-doped inner cladding 3 is 0.40%-0.96%, and as is shown in FIG. 2, the refractive index of the second fluorine-doped inner cladding 3 is smaller than that of the first fluorine-doped inner cladding 2; and the maximum relative refractive index difference 3.sub.max between the second fluorine-doped inner cladding 3 and the outer cladding 4 is 0.28%-1.09%.

(8) The single-mode optical fiber is further clad with an optical fiber coating prepared from one or two of high-temperature resistant acrylic resin, silicone rubber, polyimide, carbon and metal. By adoption of different coating materials, the optical fiber can adapt to different environment temperatures. When the optical fiber coating is prepared from ultraviolet-cured silicone rubber or high-temperature resistant acrylic resin, the single side thickness of the coating is 605 m, and the operating temperature of the single-mode optical fiber is 40-150 C. When the optical fiber coating is prepared from heat-cured silicone rubber, the single side thickness of the coating is 204 m, and the operating temperature of the single-mode optical fiber is 50-150 C. When the optical fiber coating is prepared from heat-cured polyimide, the single side thickness of the coating is 1531 m, and the operating temperature of the single-mode optical fiber is 50-400 C. When the optical fiber coating is prepared from carbon the single side thickness of the coating is 153 m, and the operating temperature of the single-mode optical fiber is 50-350 C. When the optical fiber coating is prepared from metal, the single side thickness of the coating is 153 m, and the operating temperature of the single-mode optical fiber is 200-700 C.; and the metal is gold, silver, copper and aluminum or the alloy of any two of these metals.

(9) A detailed description of the present invention is given with seven specific embodiments as follows.

(10) According to the detection method adopted in the embodiments of the present invention, at the temperature of about 24 C., a cobalt-60 radiation source is used to irradiate the optical fiber with the dose rate of 0.45 Gy/s, and the total dose is 2000 kGy. During irradiation, the attenuation caused by radiation, of the optical fiber is measured through a light source with the wavelength of 1310 nm. More details about the plotting device and the testing process for the attenuation incremental data after radiation in Table 1 can be obtained from the following publication: Jochen Kuhnhenn. Stefan Klaus and Udo Weinand, Quality Assurance for Irradiation Tests of Optical Fibers: Uncertainty and Reproducibility, IEEE Transactions on Nuclear Science, Vol. 56, No. 4, August 2009, at 2160-2166.

(11) The embodiments 1-7 and detection data are shown in Table 1.

(12) TABLE-US-00001 TABLE 1 Embodiments 1-7 and detection data serial number 1 2 3 4 5 6 7 fluorine 0 0.2 0.2 0.2 0.2 0.3 0.45 content of the core (wt %) chlorine 0.01 0.01 0.01 0.03 0.01 0.1 0.05 content of the core (wt %) fluorine 1.17 1.37 1.37 1.37 1.37 1.55 1.00 content of the first fluorine- doped inner cladding (wt %) fluorine 4.08 3.03 3.45 3.45 3.45 4.09 5.00 content of the second fluorine- doped inner cladding (wt %) 1.sub.max (%) 0.28 0.28 0.28 0.28 0.28 0.30 0.133 2.sub.max (%) 0.7 0.4 0.5 0.5 0.5 0.61 0.96 3.sub.max (%) 0.28 0.28 0.28 0.78 0.78 0.91 1.093 R1(m) 4 3.9 4 4 4 4 4.3 R2(m) 5 34 12 12 12 30 12 R3(m) 22 45 22 48 25 46 36 R4(m) 60.5 62.5 62.5 64.5 62.5 62.5 62.5 attenuation 0.345 0.444 0.338 9.342 0.344 0.322 0.334 coefficient at the wavelength of 1310 mm (dB/km) attenuation 0.196 0.592 0.191 12.197 0.19 0.185 0.196 coefficient at the wavelength of 1550 nm (dB/km) attenuation 0.199 0.594 0.194 12.203 0.193 0.186 0.197 coefficient at the wavelength of 1625 mn (dB/km) coating acrylic poly- carbon/ copper acrylic silicone acrylic materials resin imide acrylic resin rubber/acrylic resin resin resin single side 60 15 75 20 60 82 60 length of the coasting (m) radiation 14.8 5.6 93 3.5 12.4 12.8 14.8 additional loss (dB/km) additional loss 0.11 0.25 0.13 0.31 0.12 0.11 0.27 at the wavelength of 1550 nm under the bending diameter of 10 mm (dB/circle) additional loss 0.21 0.33 0.26 0.42 0.23 0.21 0.38 at the wavelength of 1625 nm under the bending diameter of 10 mm (dB/circle)

(13) From Table 1, compared with conventional radiation-resistant single-mode optical fibers, the bending-insensitive, radiation-resistant single-mode optical fiber provided by the present invention dramatically reduces additional losses, the bending loss is also dramatically reduced, and by adoption of various coating materials, the optical fiber has good radiation resistance and high temperature resistance. Under the gamma radiation dose of 2000 kGy, the single-mode optical fiber has a radiation additional loss below 14.8 dB/km at the wavelength of 1310 nm. The single-mode optical fiber has the minimum bending loss of 0.08 dB at the wavelength of 1550 nm and the minimum bending loss of 0.25 dB at the wavelength of 1625 nm when wound by one circle under the bending diameter of 15 mm

(14) Wherein, the sixth embodiment is the optimal embodiment. By mass percent, in the sixth embodiment, the core of the single-mode optical fiber has a fluorine dopant content of 0.3% and a fluorine content of 0.1%; and the first fluorine-doped inner cladding has a fluorine concentration of 1.55%, and the second fluorine-doped inner cladding has a fluorine concentration of 4.09%. The radius R1 of the core of the single-mode optical fiber is 4 m, the radius R2 of the first fluorine-doped inner cladding is 30 m, and the radius R3 of the second fluorine-doped inner cladding is 46 m; and the maximum relative refractive index difference 1.sub.max between the core and the first fluorine-doped inner cladding is 0.30%, the maximum relative refractive index difference 2.sub.max between the first fluorine-doped inner cladding and the second fluorine-doped inner cladding is 0.61%, and the maximum relative refractive index difference 3.sub.max between the second fluorine-doped inner cladding and the outer cladding 4 is 0.91%.

(15) The single-mode optical fiber has a bending loss of 0.11 dB at the wavelength of 1550 nm and a bending loss of 0.21 dB at the wavelength of 1625 nm when wound by one circle under the bending diameter of 10 mm; and the single-mode optical fiber has an attenuation coefficient of 0.322 dB/km at the wavelength of 1310 nm, an attenuation coefficient of 0.185 dB/km at the wavelength of 1550 nm and an attenuation coefficient of 0.186 dB/km at the wavelength of 1625 nm.

(16) The calculation formula involved in the present invention is as follows:

(17) The relative refractive index difference:

(18) $\%=\left[\frac{n_i^2-n_0^2}{2*n_i^2}\right]100\%\frac{n_i-n_0}{n_0}100\%$

(19) Wherein, n.sub.i is the refractive index of the core or the claddings at the wavelength of 1300 nm, and n.sub.0 is the refractive index of the adjacent outer cladding at the wavelength of 1300 nm.

(20) Various modifications and transformations of the embodiments of the present invention can be made by those skilled in the field, and if these modifications and transformations are within the scope of the claims of the present invention and equivalent techniques, these modifications and transformations are also within the protection scope of the present invention.

(21) The content, not illustrated in detail, in the description belongs to the prior art known to those skilled in the field.