Optical fiber and method of making an optical fiber

Abstract

The application provides an optical fiber and a preparation method thereof, and relates to the field of optical fibers.The optical fiber provided by the application comprises a fiber core, a cladding, a stress layer and a coating layer, the cladding is coated outside the fiber core, the stress layer is embedded in the cladding, the stress layer has two, the two stress layers are uniformly arranged around the periphery of the fiber core, and the coating layer is coated outside the cladding;the radius a of the fiber core is 2.75-3.25 mu m, the relative refractive index difference Delta n1 of the fiber core is 0.5-1%;the radius b of the cladding is 39-41 mu m, the cladding comprises a plurality of annular doped regions in a concentric circle structure in the radial direction of the cladding, the annular doped regions comprise a first annular region, the first annular region surrounds the fiber core outside, the relative refractive index difference Delta n2 of the first annular region is-0.1-0.3%, and the outer radius r2 of the first annular region and the outer diameter r1 of the inner circle of the first annular region satisfy the following relationship: (r2-r1) <= 3 mu m.The application provides an optical fiber and a preparation method thereof, and the coating layer of the optical fiber is not easy to fall off.

Description

Technical Field

[0001] This invention relates to the field of optical fibers, and in particular to an optical fiber and a method for preparing the optical fiber. Background Technology

[0002] Polarization-maintaining fiber, also known as polarization-preserving fiber, works by artificially increasing birefringence through stress to maintain the polarization state of transmitted light. The main method involves creating stress regions within the fiber to increase its birefringence coefficient, thus preserving the polarization state of light during propagation. Polarization-maintaining fibers can be categorized by structure, including panda-shaped, butterfly-shaped, bowtie-shaped, and elliptical-core types, among others.

[0003] In the prior art, polarization-maintaining optical fibers are usually used as fiber optic gyroscopes. The optical fibers need to be wound before use. However, when existing polarization-maintaining optical fibers are wound and used, the outer coating is prone to peeling off. Summary of the Invention

[0004] To address at least one of the problems mentioned in the background art, the present invention provides an optical fiber and a method for preparing the optical fiber, wherein the coating on the optical fiber is not easily peeled off.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] In a first aspect, the present invention provides an optical fiber, comprising a core, a cladding, a stress layer, and a coating, wherein the cladding covers the outside of the core, the stress layer is embedded in the cladding, there are two stress layers, the two stress layers are uniformly arranged around the periphery of the core, and the coating is applied to the outside of the cladding.

[0007] The core radius a is 2.75μm to 3.25μm, and the relative refractive index difference Δn1 of the core is 0.5% to 1%.

[0008] The cladding radius b is 39 μm to 41 μm. Along the radial direction of the cladding, it includes multiple concentric annular doped regions. Each annular doped region includes a first annular region surrounding the fiber core. The relative refractive index difference Δn2 of the first annular region is -0.1% to 0.3%. The outer radius r2 of the first annular region and the inner outer diameter r1 of the first annular region satisfy the following relationship:

[0009] (r2-r1)≤3μm

[0010] The relative refractive index difference is the difference between the refractive index of the target region on the optical fiber and the refractive index of silicon dioxide.

[0011] As an optional implementation, the ratio of the distance r between the two stress layers to the core radius a is between 3 and 4, the stress layers are doped with B2O3 at a concentration of 17 mol% to 26 mol%, and the value of (r+t) / b ranges from 0.7 to 0.85, where t is the diameter of the stress layer.

[0012] As an optional implementation, the annular doped region further includes a second annular region and a third annular region, the second annular region surrounding the first annular region and the third annular region surrounding the second annular region, the relative refractive index difference Δn of the second annular region being... a Calculated using the following formula:

[0013]

[0014] Wherein, Δn3 is the relative refractive index difference of the third annular region, Δn3 is between -0.1% and -0.5%, r3 is the outer radius of the second annular region, (r3-r2)≤2.5μm, and r4 is the outer radius of the third annular region, 2μm≤(r4-r3)≤6μm.

[0015] As an optional implementation, the annular doped region further includes a fourth annular region and a fifth annular region, the fourth annular region surrounding the third annular region and the fifth annular region surrounding the fourth annular region, the relative refractive index difference Δn of the fourth annular region being... b Calculated using the following formula:

[0016]

[0017] Wherein, Δn4 is the relative refractive index difference of the fifth annular region, Δn4 is between 0 and -0.25%, r5 is the outer radius of the fourth annular region, (r5-r4)≤2.5μm, 1μm≤(r6-r5)≤2.5μm, and r6 is the outer radius of the fifth annular region.

[0018] As an optional implementation, the annular doped region further includes a sixth annular region, a seventh annular region, and an eighth annular region. The sixth annular region surrounds the fifth annular region, the seventh annular region surrounds the sixth annular region, and the eighth annular region surrounds the seventh annular region. The relative refractive index difference Δn of the sixth annular region... c Calculated using the following formula:

[0019]

[0020] Wherein, Δn5 is -0.5% to -1.2%, r7 is the outer radius of the sixth annular region, and 6μm≤(r7-r6)≤12μm;

[0021] The relative refractive index difference Δn in the seventh annular region d Calculated using the following formula:

[0022]

[0023] Wherein, Δn6 is the relative refractive index difference of the eighth annular region, and the value of Δn6 is 0; r8 is the outer radius of the seventh annular region, 7μm≤(r8-r7)≤13μm, 39μm≤(r9-r8)≤41μm; and r9 is the radius of the cladding.

[0024] As an optional implementation, the coating material is acrylic resin.

[0025] As an optional implementation, the coating includes a first coating and a second coating, wherein the first coating is applied to the outside of the cladding and the second coating is applied to the outside of the first coating, and the first coating uses an acrylic resin with a Young's modulus of less than 1.5 MPa and an elongation at break of greater than or equal to 130%.

[0026] As an optional implementation, the second coating uses an acrylic resin with a Young's modulus of 900 MPa to 1500 MPa, an elongation at break of ≥10%, and a glass transition temperature of 70°C to 150°C.

[0027] In a second aspect, the present invention also provides a method for preparing an optical fiber, applicable to the optical fiber of the first aspect, comprising the following steps:

[0028] The optical fiber preform is melted at a temperature of 800℃~2000℃;

[0029] The molten optical fiber preform is drawn into an optical fiber body at a speed of 300 m / min to 500 m / min;

[0030] The first coating is applied to the surface of the optical fiber body at a temperature of 36℃ to 44℃;

[0031] The second coating is applied to the surface of the first coating at a temperature of 25–33°C;

[0032] The first and second coatings are cured to form an optical fiber;

[0033] Take the optical fiber onto the fiber take-up reel;

[0034] The curing degree of the first coating is 82% to 86%, and the curing degree of the second coating is 88% to 92%.

[0035] As an optional implementation, before curing the first coating and the second coating to form an optical fiber, the method further includes: performing surface inspection on the cured optical fiber, and applying the first coating to the surface of the optical fiber if the inspection fails.

[0036] The optical fiber provided by this invention includes a core, a cladding, a stress layer, and a coating. The cladding covers the outside of the core, and the stress layers are embedded in the cladding. There are two stress layers, which are uniformly arranged around the periphery of the core. The coating is applied to the outside of the cladding. The radius a of the core is 2.75 μm to 3.25 μm, and the relative refractive index difference Δn1 of the core is 0.5% to 1%. The radius b of the cladding is 39 μm to 41 μm. Along the radial direction of the cladding, the cladding includes multiple annular doped regions with a concentric circular structure. The annular doped region includes a first annular region, which surrounds the outside of the core. The relative refractive index difference Δn2 of the first annular region is -0.1% to 0.3%. The outer radius r2 of the first annular region and the inner outer diameter r1 of the first annular region satisfy the following relationship: (r2-r1)≤3μm. The optical fiber provided by this invention divides the cladding into multiple annular doped regions and rationally designs the refractive indices of the fiber core and the doped regions, so that the relative refractive index difference Δn1 between the fiber core and silicon dioxide is 0.5% to 1%, and the relative refractive index difference Δn2 between the first annular region and silicon dioxide is -0.1% to 0.3%. This makes the stress inside the optical fiber more uniform, reduces local stress, and avoids the outer coating of the optical fiber from peeling off due to excessive local stress and uneven stress distribution when the optical fiber is bent, thereby improving the reliability of the optical fiber. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the structure of an optical fiber provided in an embodiment of the present invention;

[0039] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0040] Figure 3 This is a flowchart of an optical fiber fabrication method provided in an embodiment of the present invention.

[0041] Figure label:

[0042] 100-fiber optic cable;

[0043] 110-core fiber;

[0044] 120-cladding;

[0045] 121 - First Ring Region;

[0046] 122 - Second Ring Region;

[0047] 123 - Third Ring Area;

[0048] 124 - Fourth Ring Area;

[0049] 125 - Fifth Ring Area;

[0050] 126 - Sixth Ring Area;

[0051] 127 - Seventh Ring Area;

[0052] 128 - Eighth Ring Area;

[0053] 130 - Stress layer;

[0054] 140 - First coating;

[0055] 150 - Second coating. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] Polarization-maintaining fiber is commonly used in fiber optic gyroscopes and requires winding. Typically, hundreds of meters of fiber are wound into a gyroscope. If the coating peels off, the exposed fiber portion will be directly damaged without protection, affecting the fiber's performance. In current traditional technologies, the fiber coating is easily affected by stress after curing, leading to peeling.

[0058] In view of this, the present invention provides an optical fiber 100, which divides the cladding 120 into multiple annular doped regions and rationally designs the refractive index of the fiber core 110 and the doped regions, so that the relative refractive index difference Δn1 between the fiber core 110 and silicon dioxide is 0.5% to 1%, and the relative refractive index difference Δn2 between the first annular region 121 and silicon dioxide is -0.1% to 0.3%, thereby making the stress inside the optical fiber 100 more uniform, reducing local stress, and preventing the outer coating of the optical fiber 100 from peeling off due to excessive local stress and uneven stress distribution when the optical fiber 100 is bent, thus improving the reliability of the optical fiber 100.

[0059] Figure 1 This is a schematic diagram of the structure of an optical fiber provided in an embodiment of the present invention; Figure 2 for Figure 1 Enlarged view of point A in the middle; Figure 3 This is a flowchart illustrating an optical fiber fabrication method provided in an embodiment of the present invention. Figure 1 and Figure 2 As shown, the present invention provides an optical fiber 100, including a fiber core 110, a cladding 120, a stress layer 130 and a coating. The cladding 120 covers the outside of the fiber core 110, the stress layer 130 is embedded in the cladding 120, there are two stress layers 130, the two stress layers 130 are evenly arranged around the periphery of the fiber core 110, and the coating is applied to the outside of the cladding 120.

[0060] The radius a of the core 110 is 2.75μm to 3.25μm, and the relative refractive index difference Δn1 of the core 110 is 0.5% to 1%.

[0061] The radius b of the cladding 120 is 39 μm to 41 μm. Along the radial direction of the cladding 120, the cladding 120 includes multiple concentric annular doped regions. Each annular doped region includes a first annular region 121, which surrounds the core 110. The relative refractive index difference Δn2 of the first annular region 121 is -0.1% to 0.3%. The outer radius r2 of the first annular region 121 and the inner outer diameter r1 of the first annular region 121 satisfy the following relationship:

[0062] (r2-r1)≤3μm

[0063] The relative refractive index difference is the difference between the refractive index of the target region on the optical fiber 100 and the refractive index of silicon dioxide.

[0064] The target area refers to the current area, which can represent the fiber core 110, the first annular region 121, etc.

[0065] It is understood that the refractive index of different positions of optical fiber 100 can be changed by doping it with elements such as germanium, phosphorus, boron, and fluorine. Among them, doping with germanium and phosphorus can increase the refractive index, while doping with boron and fluorine can decrease the refractive index. In this embodiment of the invention, the type of doping element is not limited, as long as it meets the refractive index requirements.

[0066] The optical fiber 100 provided in this embodiment of the invention divides the cladding 120 into multiple annular doped regions and rationally designs the refractive index of the fiber core 110 and the doped regions. This results in a relative refractive index difference Δn1 between the fiber core 110 and silicon dioxide of 0.5% to 1%, and a relative refractive index difference Δn2 between the first annular region 121 and silicon dioxide of -0.1% to 0.3%. This makes the stress inside the optical fiber 100 more uniform, reduces local stress, and prevents the outer coating of the optical fiber 100 from peeling off due to excessive local stress and uneven stress distribution when the optical fiber 100 is bent, thus improving the reliability of the optical fiber 100. However, excessively large or small Δn1 and Δn2 will cause excessive stress concentration in the optical fiber 100 when bent, thereby increasing the risk of the outer coating peeling off.

[0067] In the above embodiments, the ratio of the distance r between the two stress layers 130 to the radius a of the fiber core 110 can be between 3 and 4. The stress layer 130 is doped with B2O3 at a concentration of 17 mol% to 26 mol%, and the value of (r+t) / b ranges from 0.7 to 0.85, where t is the diameter of the stress layer 130. By doping the stress layer 130 with an appropriate amount of B2O3, the shrinkage coefficient of the stress layer 130 after heating can be higher than that of the cladding 120, thereby improving the adhesion between the stress layer 130 and the cladding 120, making the internal structure of the optical fiber 100 more compact and robust.

[0068] In the above embodiments, the annular doped region may further include a second annular region 122 and a third annular region 123. The second annular region 122 surrounds the first annular region 121, and the third annular region 123 surrounds the second annular region 122. The relative refractive index difference Δn of the second annular region 122 is... a Calculated using the following formula:

[0069]

[0070] Wherein, Δn3 is the relative refractive index difference of the third annular region 123, and Δn3 is between -0.1% and -0.5%. r3 is the outer radius of the second annular region 122, (r3-r2)≤2.5μm. r4 is the outer radius of the third annular region 123, and 2μm≤(r4-r3)≤6μm.

[0071] In the above embodiments, the annular doped region may further include a fourth annular region 124 and a fifth annular region 125. The fourth annular region 124 surrounds the third annular region 123, and the fifth annular region 125 surrounds the fourth annular region 124. The relative refractive index difference Δn of the fourth annular region 124 is... b Calculated using the following formula:

[0072]

[0073] Wherein, Δn4 is the relative refractive index difference of the fifth annular region 125, and Δn4 is between 0 and -0.25%. r5 is the outer radius of the fourth annular region 124, (r5-r4)≤2.5μm, 1μm≤(r6-r5)≤2.5μm, and r6 is the outer radius of the fifth annular region 125.

[0074] In the above embodiments, the annular doped region may further include a sixth annular region 126, a seventh annular region 127, and an eighth annular region 128. The sixth annular region 126 surrounds the fifth annular region 125, the seventh annular region 127 surrounds the sixth annular region 126, and the eighth annular region 128 surrounds the seventh annular region 127. The relative refractive index difference Δn of the sixth annular region 126 is...c Calculated using the following formula:

[0075]

[0076] Wherein, Δn5 is -0.5% to -1.2%, r7 is the outer radius of the sixth annular region 126, and 6μm≤(r7-r6)≤12μm;

[0077] The relative refractive index difference Δn in the seventh annular region 127 d Calculated using the following formula:

[0078]

[0079] Wherein, Δn6 is the relative refractive index difference of the eighth annular region 128, and the value of Δn6 is 0; r8 is the outer radius of the seventh annular region 127, 7μm≤(r8-r7)≤13μm, 39μm≤(r9-r8).

[0080] ≤41μm, r9 is the radius of cladding 120. By dividing cladding 120 into multiple doped regions with different refractive indices, the internal structure of optical fiber 100 can be made more stable, further preventing coating peeling and improving the service life of optical fiber 100.

[0081] In the above embodiments, the coating material can be acrylic resin. Acrylic resin has advantages such as high transparency, good weather resistance, high hardness, and good wear resistance. These advantages make the optical fiber 100 more stable during use and improve the quality of transmitted signals. Furthermore, acrylic resin also has good flexibility and impact resistance, making the optical fiber 100 less susceptible to damage when subjected to external forces. In addition, acrylic resin has good chemical corrosion resistance, allowing it to be used in harsh environments.

[0082] In the above embodiments, the coating may include a first coating 140 and a second coating 150. The first coating 140 is applied to the outside of the cladding 120, and the second coating 150 is applied to the outside of the first coating 140. The first coating 140 uses an acrylic resin with a Young's modulus of less than 1.5 MPa and an elongation at break of greater than or equal to 130%. Using the acrylic resin of the specifications in this embodiment as the first coating 140 can improve the flexibility of the coating, make the first coating 140 bond more firmly to the cladding 120, and withstand greater bending stress without falling off.

[0083] In the above embodiments, the second coating 150 uses an acrylic resin with a Young's modulus of 900 MPa to 1500 MPa, an elongation at break of ≥10%, and a glass transition temperature of 70°C to 150°C. Using the acrylic resin of the specifications in this embodiment as the second coating 150 can improve the hardness of the coating and enhance the wear resistance of the outer coating. This double-layer coating structure, which is softer inside and harder outside, can improve the adhesion between the fiber optic 100 coating and the cladding 120, reducing the risk of detachment, and also improve the wear resistance of the coating, thus extending its service life.

[0084] The optical fiber 100 provided in this embodiment of the invention includes a core 110, a cladding 120, a stress layer 130, and a coating. The cladding 120 covers the core 110, and the stress layer 130 is embedded in the cladding 120. There are two stress layers 130, which are uniformly arranged around the periphery of the core 110. The coating is applied to the outside of the cladding 120. The radius α of the core 110 is 2.75 μm to 3.25 μm, and the relative refractive index difference Δn1 of the core 110 is 0.5% to 1%. The radius b of 0 is 39μm to 41μm. Along the radial direction of the cladding 120, the cladding 120 includes a plurality of annular doped regions in a concentric circle structure. The annular doped region includes a first annular region 121. The first annular region 121 surrounds the core 110. The relative refractive index difference Δn2 of the first annular region 121 is -0.1% to 0.3%. The outer radius r2 of the first annular region 121 and the inner outer diameter r1 of the first annular region 121 satisfy the following relationship: (r2-r1)≤3μm. The optical fiber 100 provided in this embodiment of the invention divides the cladding 120 into multiple annular doped regions and rationally designs the refractive index of the fiber core 110 and the doped regions, so that the relative refractive index difference Δn1 between the fiber core 110 and silicon dioxide is 0.5% to 1%, and the relative refractive index difference Δn2 between the first annular region 121 and silicon dioxide is -0.1% to 0.3%. This makes the stress inside the optical fiber 100 more uniform, reduces local stress, and avoids the outer coating of the optical fiber 100 from peeling off due to excessive local stress and uneven stress distribution when the optical fiber 100 is bent, thereby improving the reliability of the optical fiber 100.

[0085] Furthermore, this embodiment of the invention also provides a method for fabricating an optical fiber 100, applied to the optical fiber 100 in the above embodiments, comprising the following steps:

[0086] S100. Melt the optical fiber preform at a temperature of 800℃~2000℃.

[0087] The optical fiber preform is melted at high temperature, which transforms it from a solid state to an intermediate state between solid and liquid, facilitating subsequent thermal processing. The preform can be heated using graphite heating or induction coil heating. The environment surrounding the preform is filled with a protective gas, which can be helium, argon, or a mixture thereof. Helium accounts for less than 20% of the total gas content, the total gas flow rate is (10L~30L) / min, and the oxygen concentration is less than 50ppm.

[0088] S200: The molten optical fiber preform is drawn into an optical fiber body at a speed of 300m / min to 500m / min.

[0089] It is understandable that the preform is heated and melted in the drawing furnace. The heating temperature is related to the non-contact tension reading. At a certain speed, the higher the heating temperature, the lower the non-contact tension. Using non-contact tension as the control standard, the heating temperature (or power) can meet the requirement that the non-contact tension reading is between 30g and 85g.

[0090] S300. The first coating 140 is applied to the surface of the optical fiber body at a temperature of 36℃ to 44℃.

[0091] S400, the second coating 150 is applied to the surface of the first coating 140 at a temperature of 25-33°C.

[0092] In particular, if the coating temperature of the first coating 140 and the second coating 150 is too high or too low, the coating quality will be affected.

[0093] S500, the first coating 140 and the second coating 150 are cured to form optical fiber 100, wherein the curing degree of the first coating 140 is 82% to 86% and the curing degree of the second coating 150 is 88% to 92%.

[0094] After curing, the size of optical fiber 100 can be reduced to approximately 5 μm smaller than the target size (e.g., if the target size of optical fiber 100 is 135 μm, then the size of optical fiber 100 after curing will be approximately 130 μm). The coating curing can be performed using either ultraviolet curing or LED curing. The curing environment is isolated using one or a mixture of nitrogen, helium, and argon gases. The gas flow rate of a single curing oven is controlled between 5 L and 20 L. The oxygen content in the curing environment is less than 100 ppm. During the curing process, the optical fiber 100 can be exposed to the air environment for no more than 0.02 seconds when passing through different curing ovens. After curing in the curing oven, the curing degree of the inner coating (first coating 140) of optical fiber 100 is 88%–94%, and the curing degree of the outer coating (second coating 150) is 92%–98%.

[0095] S600, take fiber optic cable 100 onto the fiber take-up reel.

[0096] Before winding the fiber 100 onto the fiber take-up reel, the strength of the fiber 100 can be tested. Fiber 100 with a strength greater than or equal to 100 kpsi can be wound onto the fiber 100 reel.

[0097] In the above embodiments, before curing the first coating 140 and the second coating 150 to form the optical fiber 100, the method further includes: performing surface inspection on the cured optical fiber 100, and coating the surface of the optical fiber 100 with the first coating 140 if the inspection fails. This step is similar to coloring, and the selected coating material is the same as that of the first coating 140. After this step, damage to the coating of the optical fiber 100 caused by various reasons during the preparation process can be repaired, thereby improving the quality of the optical fiber 100.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optical fiber, characterized in that, The fiber includes a core, a cladding, a stress layer, and a coating. The cladding covers the outside of the core, the stress layer is embedded in the cladding, and there are two stress layers. The two stress layers are evenly arranged around the periphery of the core, and the coating is applied to the outside of the cladding. The radius a of the fiber core is 2.75 μm to 3.25 μm, and the relative refractive index difference Δn1 of the fiber core is 0.5% to 1%. The radius b of the cladding is 39 μm to 41 μm. Along the radial direction of the cladding, the cladding includes multiple concentric annular doped regions. Each annular doped region includes a first annular region surrounding the fiber core. The relative refractive index difference Δn2 of the first annular region is -0.1% to 0.3%. The outer radius r2 of the first annular region and the inner outer diameter r1 of the first annular region satisfy the following relationship: (r2 - r1) ≤ 3μm Wherein, the relative refractive index difference is the difference between the refractive index of the target region on the optical fiber and the refractive index of silicon dioxide; The ratio of the distance r between the two stress layers to the core radius a is between 3 and 4. The stress layers are doped with B2O3 at a concentration of 17 mol% to 26 mol%, and the value of (r+t) / b ranges from 0.7 to 0.85, where t is the diameter of the stress layer.

2. The optical fiber according to claim 1, characterized in that, The annular doped region further includes a second annular region and a third annular region, the second annular region surrounding the first annular region, and the third annular region surrounding the second annular region. The relative refractive index difference Δn between the second annular regions is... a Calculated using the following formula: Wherein, Δn3 is the relative refractive index difference of the third annular region, Δn3 is between -0.1% and -0.5%, r3 is the outer radius of the second annular region, (r3- r2)≤2.5μm, and r4 is the outer radius of the third annular region, 2μm≤(r4-r3)≤6μm.

3. The optical fiber according to claim 2, characterized in that, The annular doped region further includes a sixth annular region, a seventh annular region, and an eighth annular region. The sixth annular region surrounds the fifth annular region, the seventh annular region surrounds the sixth annular region, and the eighth annular region surrounds the seventh annular region. The relative refractive index difference Δn of the sixth annular region... c Calculated using the following formula: Wherein, Δn5 is -0.5% to -1.2%, r7 is the outer radius of the sixth annular region, and 6μm≤(r7-r6)≤12μm; The relative refractive index difference Δn in the seventh annular region d Calculated using the following formula: Wherein, Δn6 is the relative refractive index difference of the eighth annular region, and the value of Δn6 is 0; r8 is the outer radius of the seventh annular region, and 7μm≤(r8-r7)≤13μm.

4. The optical fiber according to any one of claims 1-3, characterized in that, The coating material is acrylic resin.

5. The optical fiber according to claim 4, characterized in that, The coating comprises a first coating and a second coating. The first coating is applied to the outside of the cladding, and the second coating is applied to the outside of the first coating. The first coating uses an acrylic resin with a Young's modulus of less than 1.5 MPa and an elongation at break of greater than or equal to 130%.

6. The optical fiber according to claim 5, characterized in that, The second coating uses an acrylic resin with a Young's modulus of 900 MPa to 1500 MPa, an elongation at break of ≥10%, and a glass transition temperature of 70°C to 150°C.

7. A method for fabricating optical fibers, characterized in that, Applied to the optical fiber of claim 5 or 6, the method includes the following steps: The optical fiber preform is melted at a temperature of 800°C to 2000°C; The molten optical fiber preform is drawn into an optical fiber body at a speed of 300 m / min to 500 m / min; The first coating is applied to the surface of the optical fiber body at a temperature of 36°C to 44°C; The second coating is applied to the surface of the first coating at a temperature of 25–33°C; The first coating and the second coating are cured to form an optical fiber; The optical fiber is retrieved onto the fiber take-up reel; The curing degree of the first coating is 82% to 86%, and the curing degree of the second coating is 88% to 92%.

8. The optical fiber fabrication method according to claim 7, characterized in that, Before curing the first coating and the second coating to form an optical fiber, the method further includes: performing surface inspection on the cured optical fiber, and coating the surface of the optical fiber with the first coating if the inspection fails.

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