High bandwidth radiation-resistant multimode optical fiber

Abstract

A high bandwidth radiation-resistant multimode optical fiber includes a core and a cladding layer surrounding the core. The core is a fluorine-doped quartz glass layer with a graded refractive index distribution and a distribution power exponent of 1.7-2.2. The core has R1 of 15-35 m and 1%min of 0.8% to 1.2%. The cladding layer has an inner cladding layer having R2 of 15-38 m and 2% of 0.8% to 1.2% and/or a depressed inner cladding layer having R3 of 15-55 m and 3 of 1.0% to 1.4%, an intermediate cladding layer having R4 of 15.5-58 m and 4 of 0.7% to 0.2% a depressed cladding layer hasving R5 of 16-60 m and 5 of 0.8% to 1.2%, and an outer cladding layer sequentially formed from inside to outside. The outer cladding layer is a pure silica glass layer.

Claims

1. A high bandwidth radiation-resistant multimode optical fiber, comprising a core layer and a cladding layer, wherein the core layer is a fluorine-doped quartz glass layer with a graded refractive index distribution and a distribution power exponent in a range from 1.7 to 2.2, and the core layer has a minimum relative refractive index difference 1% min in a range from 0.8% to 1.2% and a radius R1 in a range from 15 m to 35 m; and wherein the cladding layer outside of the core layer comprises an inner cladding layer and/or a depressed inner cladding layer, an intermediate cladding layer, a depressed cladding layer, and an outer cladding layer in sequence from inside to outside, wherein: the inner cladding layer has a radius R2 in a range from 15 m to 38 m and a relative refractive index difference 2% in a range from 0.8% to 1.2%; the depressed inner cladding layer has a radius R3 in a range from 15 m to 55 m and a relative refractive index difference 3 in a range from 1.0% to 1.4%; the intermediate cladding layer has a radius R4 in a range from 15.5 m to 58 m and a relative refractive index difference 4 in a range from 0.7% to 0.2%; the depressed cladding layer has a radius R5 in a range from 16 m to 60 m and a relative refractive index difference 5 in a range from 0.8% to 1.2%; and the outer cladding layer is a pure silica glass layer.

2. The high bandwidth radiation-resistant multimode optical fiber according to claim 1, wherein the core layer has a maximum relative refractive index difference 1% max in a range from 0.01% to 0%.

3. The high bandwidth radiation-resistant multimode optical fiber according to claim 1, wherein a numerical aperture NA of the optical fiber is in a range from 0.17 to 0.24.

4. The high bandwidth radiation-resistant multimode optical fiber according to claim 1, wherein the inner cladding layer, the depressed inner cladding layer, the intermediate cladding layer, and the depressed cladding layer are all fluorine-doped quartz glass layers made of SiO.sub.2-F.

5. The high bandwidth radiation-resistant multimode optical fiber according to claim 1, wherein the optical fiber has a bandwidth in a range from 920 MHz-km to 4650 MHz-km at an 850 nm wavelength window.

6. The high bandwidth radiation-resistant multimode optical fiber according to claim 1, wherein the optical fiber has a bandwidth in a range from 860 MHz-km to 2650 MHz-km at a 1300 nm wavelength window.

7. The high bandwidth radiation-resistant multimode optical fiber according to claim 1, wherein a coating layer of the optical fiber is one or two of an acrylic resin coating, a polyimide coating, and a silicone rubber coating.

8. The high bandwidth radiation-resistant multimode optical fiber according to claim 7, wherein the coating layer of the optical fiber is an ultraviolet curing silicone rubber coating and a high temperature resistant acrylic resin coating and has a single layer thickness of 605 m, and a working temperature of the optical fiber is in a range from 40 C. to +150 C.

9. The high bandwidth radiation-resistant multimode optical fiber according to claim 7, wherein, the coating layer of the optical fiber is a thermosetting polyimide coating and has a single layer thickness of 153 m, and a working temperature of the optical fiber is in a range from 50 C. to +400 C.

10. The high bandwidth radiation-resistant multimode optical fiber according to claim 7, wherein, the coating layer of the optical fiber is a thermosetting silicone rubber coating and has a single layer thickness of 603 m, and a working temperature of the optical fiber is in a range from 50 C. to +150 C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a diagram showing a structure of an optical fiber refractive index profile of an embodiment of the present disclosure, and

(2) FIG. 2 is a diagram showing a structure of an optical fiber refractive index profile of another embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(3) Specific embodiments are provided below to further explain the present disclosure. In the following tables, R1 is a radius of a core layer; R2 is a radius of an inner cladding layer; R3 is a radius of a depressed inner cladding layer; R4 is a radius of an intermediate cladding layer; and R5 is a radius of a depressed cladding layer. An outer cladding layer is a pure silica glass layer and has a radius in a range from 50 m to 62.5 m.

Embodiment 1

(4) According to design of the technical solution (as shown in FIG. 1), a cladding layer comprises an inner cladding layer and a depressed inner cladding layer. A group of preforms are manufactured according to the manufacturing method. A drawing process is performed with a drawing speed of 200 m/min and a bare optical fiber tension of 20 g. Main performance parameters are shown in a table as follows.

(5) TABLE-US-00001 Embodiment 1 1 2 3 4 5 R1 (m) 16 18 20 25 31.25 R2 (m) 18 22 24 30 35 R3 (m) 25 28 32 38 45 R4 (m) 27 31 36 45 50 R5 (m) 30 35 42 48 55 Core Layer Distribution 1.8 1.85 2.03 1.98 2.1 Power Exponent 1% min 0.85 0.9 1.1 1.0 1.2 2% 0.85 0.9 1.1 1.0 1.2 3% 1.0 1.1 1.3 1.4 1.35 4% 0.3 0.6 0.55 0.7 0.66 5% 0.84 0.9 1.08 1.09 1.15 Numerical Aperture 0.184 0.19 0.205 0.2 0.22 850 nm Bandwidth 920 1100 3520 4630 2200 (MHz-km) 1300 nm Bandwidth 2610 1720 960 1160 867 (MHz-km) Material of Coating Layer Acrylic Acrylic Polyimide Silicone Acrylic Resin Resin Rubber Resin/Silicone Rubber Single Layer Thickness 70 62 15 60 60 of Coating Layer 850 nm Attenuation 1.82 1.75 1.7 1.7 1.65 Coefficient (dB/km) 1300 nm Attenuation 0.42 0.4 0.32 0.35 0.3 Coefficient (dB/km) 1300 nm Attenuation 51 43 42 42 50 Increasing Amount After Irradiation (dB/km) Before 2 Ring 7.5 mm 0.2 0.13 0.2 0.11 0.08 Irradiation Bending Radius Additional Macrobending Attenuation @1300 nm (dB) 2 Ring 15 mm 0.09 0.1 0.11 0.06 0.05 Bending Radius Additional Macrobending Attenuation @1300 nm (dB) After 2 Ring 7.5 mm 0.2 0.14 0.3 0.12 0.08 Irradiation Bending Radius Additional Macrobending Attenuation @1300 nm (dB) 2 Ring 15 mm 0.1 0.1 0.12 0.06 0.06 Bending Radius Additional Macrobending Attenuation @1300 nm (dB)

Embodiment 2

(6) According to design of the technical solution (as shown in FIG. 2), a depressed inner cladding layer is not included in a cladding layer. A group of preforms are manufactured according to the manufacturing method. A drawing process is performed with a drawing speed of 200 m/min and a bare optical fiber tension of 20 g. Main performance parameters are shown in a table as follows.

(7) TABLE-US-00002 Embodiment 2 1 2 3 4 5 R1 (m) 18 20 22 25 31.25 R2 (m) 21 22 25 28.5 35 R4 (m) 25 26 31 36 40 R5 (m) 50 45 45 48 55 Core Layer Distribution 1.9 1.85 2.1 2.01 1.98 Power Exponent 1% min 0.9 0.9 1.1 1.0 1.2 2% 0.9 0.91 1.1 1.0 1.2 4% 0.4 0.5 0.6 0.7 0.8 5% 0.9 0.9 1.08 1.09 1.15 Numerical Aperture 0.19 0.19 0.205 0.2 0.22 850 nm Bandwidth 1200 900 1800 3860 3300 (MHz-km) 1300 nm Bandwidth 1630 1510 600 990 867 (MHz-km) Material of Coating Layer Acrylic Acrylic Polyimide Silicone Acrylic Resin Resin Rubber Resin/Silicone Rubber Single Layer Thickness 70 62 15 62 60 of Coating Layer 850 nm Attenuation 1.9 1.82 1.78 1.72 1.93 Coefficient (dB/km) 1300 nm Attenuation 0.44 0.27 0.34 0.21 0.4 Coefficient (dB/km) 1300 nm Attenuation 47 44 46 41 43 Increasing Amount After Irradiation (dB/km) Before 2 Ring 7.5 mm 0.13 0.15 0.13 0.3 0.23 Irradiation Bending Radius Additional Macrobending Attenuation @1300 nm (dB) 2 Ring 15 mm 0.1 0.07 0.1 0.06 0.11 Bending Radius Additional Macrobending Attenuation @1300 nm (dB) After 2 Ring 7.5 mm 0.12 0.16 0.2 0.27 0.2 Irradiation Bending Radius Additional Macrobending Attenuation @1300 nm (dB) 2 Ring 15 mm 0.12 0.1 0.11 0.07 0.2 Bending Radius Additional Macrobending Attenuation @1300 nm (dB)

(8) An irradiation detection method is based on the TIA/EIA455-64 standard. The optical fiber is continuously irradiated using a cobalt-60 source (Co60 source) -ray source with continuous pulses having an average energy of 1.25 MeV at a dose rate of 20 rad/s for 21 hours. A total radiation dose is 1500 Krad. During irradiation, an attenuation of the optical fiber under radiation conditions is measured using a light source having a wavelength of 1300 nm.

(9) A macrobending detection method is to test according to the IEC-60793-1-47 method. The optical fiber to be tested is wound by certain turns according to a certain diameter (15 mm, 20 mm, 60 mm, etc.), and then the wound optical fiber is released to test change in luminous power before and after wounding. Through the above two tests, compared with conventional multimode fibers of the same type and common bending-resistant optical fibers, the radiation-resistant multimode optical fiber provided by the present disclosure has a significantly lower attenuation coefficient and obviously less variation in attenuation coefficient under irradiation conditions. The macrobending test result shows that the optical fiber of the present disclosure has good performance.