A compressively stressed optical fiber and a manufacturing process thereof

Abstract

The application discloses a compressive stress optical fiber and a manufacturing process thereof. The compressive stress optical fiber comprises a core layer made of silica containing 200-400 ppm alkali ions, an inner cladding layer made of silica containing 5000-10000 ppm fluorine ions, an auxiliary layer made of silica containing 13000-20000 ppm halogen ions, and a pre-stress layer made of silica containing 5-20 ppm aluminum ions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical fiber manufacturing, for example to a compressive stress optical fiber and a manufacturing process thereof. BACKGROUND

[0002] The currently widely used communication optical fiber is to increase the refractive index of the core by doping germanium element (GeO2) in the core, so as to form a refractive index difference with the cladding material of pure silica, so as to ensure the propagation of incident light in the optical fiber. However, due to the doping of oxides in the core layer, the stability of the optical fiber in the hydrogen element and gamma ray radiation environment is destroyed, so the attenuation value of the germanium-doped optical fiber is high.

[0003] Therefore, there is an urgent need for a compressive stress optical fiber and a manufacturing process thereof to solve the above problems. SUMMARY

[0004] The present application aims to provide a compressive stress optical fiber and a manufacturing process thereof, which realizes the attenuation value of the optical fiber at 1550nm wavelength ≤0.160db / km, reduces the transmission attenuation value of the optical fiber. Moreover, no germanium element is used, which avoids the increase of optical fiber loss caused by the material of the optical fiber itself, and further reduces the optical fiber loss.

[0005] To achieve the above purpose, the present application adopts the following technical scheme:

[0006] On the one hand, a compressive stress optical fiber is provided, comprising:

[0007] A core layer, the material of which is silica containing alkali ions, wherein the weight content of the alkali ions is 200ppm-400ppm based on the total weight of the core layer;

[0008] An inner cladding layer, which is coated on the core layer, the material of which is silica containing fluorine ions, wherein the weight content of the fluorine ions is 5000ppm-10000ppm based on the total weight of the inner cladding layer;

[0009] An auxiliary layer, which is coated on the inner cladding layer, the material of which is silica containing halogen ions, wherein the weight content of the halogen ions is 13000ppm-20000ppm based on the total weight of the auxiliary layer;

[0010] A pre-stress layer, which is coated on the auxiliary layer, the material of which is silica containing aluminum ions, wherein the weight content of the aluminum ions is 5ppm-20ppm based on the total weight of the pre-stress layer.

[0011] As an optional technical scheme of a compressive stress optical fiber, it further comprises a coating layer, which is coated on the pre-stress layer, the material of which is acrylic resin.

[0012] As an alternative technical solution of the compressive stress fiber, the outer diameter of the core layer is 9-13 μm;

[0013] The outer diameter of the inner cladding layer is 20-40 μm;

[0014] The outer diameter of the auxiliary layer is 70-90 μm;

[0015] The outer diameter of the pre-stress layer is 125-126 μm;

[0016] The outer diameter of the coating layer is 235-255 μm.

[0017] As an alternative technical solution of the compressive stress fiber, the refractive index difference Δ1 between the inner cladding layer and the core layer is about -0.25% to -0.45%;

[0018] The refractive index difference Δ2 between the auxiliary layer and the core layer is about -0.5% to -1.2%.

[0019] As an alternative technical solution of the compressive stress fiber, the oxide of alkali ion doped in the core layer includes K2O or Li2O;

[0020] The oxide of aluminum ion doped in the pre-stress layer includes Al2O3.

[0021] As an alternative technical solution of the compressive stress fiber, the coating layer is a double coating layer including an inner coating layer and an outer coating layer; or the coating layer is a single coating layer.

[0022] In another aspect, a manufacturing process of a compressive stress fiber is provided for manufacturing the compressive stress fiber according to any one of the above solutions, including the following steps:

[0023] S1, preparing the core layer in a loose body;

[0024] S2, taking out the loose body to glassify the loose body through dehydration and sintering process to form a core rod combined by the core layer and the inner cladding layer;

[0025] S3, preparing the auxiliary layer outside the core rod;

[0026] S4, preparing the pre-stress layer outside the auxiliary layer;

[0027] S5, performing a drawing process on the combination of the core layer, the inner cladding layer, the auxiliary layer and the pre-stress layer.

[0028] As an alternative technical solution of the manufacturing process of the compressive stress fiber, after step S5, a step S6 is further included to prepare a coating layer outside the pre-stress layer.

[0029] As an optional technical solution of the manufacturing process of the compressive stress optical fiber, in the S1 step, the core layer containing the alkali ions in a loose body is prepared by a vapor deposition process;

[0030] In the S2 step, the fluorine ions are incorporated in the sintering process, the alkali ions are diffused in the core layer, and the inner cladding layer containing the fluorine ions is formed outside the core layer;

[0031] In the S3 step, the sleeve of the auxiliary layer containing the halogen element is prepared, and the sleeve method process is used to sleeve the auxiliary layer outside the inner cladding layer;

[0032] In the S4 step, the sleeve of the pre-stress layer containing the aluminum ions is prepared, and the sleeve method process is used to sleeve the pre-stress layer outside the auxiliary layer;

[0033] In the S6 step, the coating layer is prepared outside the pre-stress layer by using a coating mold.

[0034] As an optional technical solution of the manufacturing process of the compressive stress optical fiber, in the S4 step, the pre-stress layer containing the aluminum ions is prepared outside the auxiliary layer by using a plasma spraying method.

[0035] The beneficial effects of the present application are:

[0036] The core layer is silica containing alkali ions, the inner cladding layer incorporates fluorine ions, and the auxiliary layer incorporates halogen ions, so that the refractive index difference between the core layer, the inner cladding layer and the auxiliary layer in the compressive stress optical fiber is realized, so that the incident light realizes total reflection transmission in the optical fiber.

[0037] The core layer material is silica with alkali ion content of 200-400 ppm, the inner cladding layer material is silica with fluorine ion content of 5000-10000 ppm, the auxiliary layer material is silica with halogen ion content of 13000-20000 ppm, and the pre-stress layer material is silica with halogen ion content of 5-20 ppm. Due to the different elements and contents in the core layer, the inner cladding layer, the auxiliary layer and the pre-stress layer, mutual stress is generated between the layers, and the stress distribution is formed by the mutual action. In the stress distribution, the compressive stress of the core layer and the inner cladding layer is -40 MPa to -20 MPa, the compressive stress of the auxiliary layer is -35 MPa to -15 MPa, and the compressive stress of the pre-stress layer is 20 MPa to 20 MPa. The optical fiber is considered from the stress to reduce the fiber loss. In the stress distribution, the attenuation value of the optical fiber at 1550 nm wavelength is ≤0.160 db / km, and the fiber transmission attenuation value is reduced. Moreover, germanium element is not used, and the increase of fiber loss caused by the material of the optical fiber itself is avoided, and the further reduction of the fiber loss is realized. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the description of the embodiments of the present application will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor based on the contents of the embodiments of the present application and the drawings.

[0039] Figure 1 is a cross-sectional view of the compressive stress optical fiber provided by the specific embodiment of the present application;

[0040] Figure 2 is a structural schematic diagram of the vapor deposition device provided by the specific embodiment of the present application.

[0041] The marks in the figure are as follows:

[0042] 1, core layer; 2, inner cladding layer; 3, auxiliary layer; 4, pre-stress layer; 5, coating layer;

[0043] 10, vapor deposition device; 101, quartz tube; 102, heating element; 103, three-way pipe; 104, alkali ion heating box. DETAILED DESCRIPTION

[0044] The present application will be further described in detail below in combination with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, it should be noted that, in order to facilitate the description, only the parts related to the present application are shown in the drawings, but not all the structures.

[0045] In the description of the present application, unless specifically defined and limited otherwise, the terms "connected", "connected", "fixed" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0046] In the present application, unless specifically defined and limited otherwise, the first feature "on" or "under" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "above" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "under", "below" and "below" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0047] In the description of the present embodiment, the terms "up", "down", "left", "right" and other orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only used to distinguish in description, and have no special meaning.

[0048] The currently widely used communication optical fiber is to increase the refractive index of the core by doping germanium element GeO2 in the core, so as to form a refractive index difference with the cladding material of pure silica, so as to ensure the propagation of incident light in the optical fiber. However, due to the doping of oxides in the core layer, the stability of the optical fiber in the hydrogen element and gamma ray radiation environment is destroyed, so the attenuation value of the germanium-doped optical fiber loss is high.

[0049] To solve the above problems, as shown in Figure 1 The present application provides a compressive stress optical fiber, which comprises a core layer 1, an inner cladding layer 2, an auxiliary layer 3, a pre-stress layer 4 and a coating layer 5.

[0050] Specifically, the material of the core layer 1 is silica containing alkali ions, the content of alkali ions in the core layer 1 is 200 ppm-400 ppm, and the specific content can be about 200 ppm, about 250 ppm, about 300 ppm, about 350 ppm or about 400 ppm. The outer diameter of the core layer 1 is 9 μm-13 μm, and the specific outer diameter can be 9 μm, 10 μm, 11 μm, 12 μm or 13 μm. Among them, the oxide of the doped alkali ion element is K2O or Li2O. Since no or almost no germanium element is doped in the core layer 1, the optical fiber attenuation caused by Rayleigh scattering is reduced, and further reduction of the optical fiber loss is achieved.

[0051] However, in order to maintain the refractive index difference between the core layer 1 and the cladding, the inner cladding layer 2 is coated outside the core layer 1, the outer diameter of the inner cladding layer 2 is 20 μm-40 μm, and the specific outer diameter value can be 20 μm, 25 μm, 30 μm or 40 μm. The material of the inner cladding layer 2 is silica containing fluorine elements, and the content of fluorine ions in the inner cladding layer 2 is 5000 ppm-10000 ppm, and the specific content can be about 5000 ppm, about 6000 ppm, about 7000 ppm, about 8000 ppm, about 9000 ppm or about 10000 ppm. The incorporation of fluorine elements, on the one hand, forms a refractive index difference Δ1 between the inner cladding layer 2 and the core layer 1, and the refractive index difference Δ1 ≈-0.25%-0.45%. Moreover, the viscosity of quartz glass is high, and the viscosity decreases after the incorporation of fluorine elements. The core layer 1 and the inner cladding layer 2 of the optical fiber are adapted in viscosity in the high-temperature molten state, the inner cladding layer 2 obtains a viscosity value close to that of the core layer 1, and at the same time, the internal stress of the core layer 1 and the inner cladding layer 2 changes.

[0052] Further, in order to form a total reflection condition inside the optical fiber, the auxiliary layer 3 is coated outside the inner cladding 2, the outer diameter of the auxiliary layer 3 is 70 μm-90 μm, and the specific outer diameter can be 70 μm, 75 μm, 80 μm, 85 μm or 90 μm. The auxiliary layer 3 is made of silicon dioxide containing halogen elements such as fluorine and chlorine, and the halogen ion content in the auxiliary layer 3 is 13000 ppm-20000 ppm, and the specific content can be about 13000 ppm, about 15000 ppm, about 17000 ppm, about 18000 ppm, about 19000 ppm or about 20000 ppm. The incorporation of halogen elements, on the one hand, reduces the refractive index of the auxiliary layer 3, and adopts a comprehensive waveguide design to form a refractive index difference Δ2 between the auxiliary layer 3 and the inner cladding 2, and the refractive index difference Δ2≈-0.5%-1.2%. When the incident light is transmitted in the compression stress optical fiber, the total reflection condition is formed under the conditions of the refractive index difference Δ1 and the refractive index difference Δ2, and the transmission loss of the incident light in the compression stress optical fiber is reduced. On the other hand, the incorporation of halogen elements further improves the bending resistance of the optical fiber, and the macro-bending level of the optical fiber is obviously improved. Furthermore, the addition of halogen elements forms a larger relative stress at the interface between the inner cladding 2 and the auxiliary layer 3.

[0053] Further, the pre-stress layer 4 is further coated outside the auxiliary layer 3, the outer diameter of the pre-stress layer 4 is 125 μm-126 μm, the pre-stress layer 4 is made of silicon dioxide containing aluminum elements, and the aluminum ion content in the pre-stress layer 4 is 5 ppm-20 ppm, and the specific content can be about 5 ppm, about 10 ppm, about 15 ppm or about 20 ppm. Among them, the oxide of the incorporated aluminum ion element is Al2O3. The pre-stress layer 4 provides compression stress for the auxiliary layer 3.

[0054] Due to the different element ions and contents in the core layer 1, the inner cladding 2, the auxiliary layer 3 and the pre-stress layer 4, mutual stress is generated between the layers, and the stress distribution map is formed by the mutual stress, and the compression stress distribution which can reduce the transmission loss of the optical fiber is formed inside the optical fiber. Specifically, the compression stress of the core layer 1 is-40 MPa--20 MPa, the compression stress of the inner cladding 2 is-40 MPa--20 MPa, the compression stress of the auxiliary layer 3 is-35 MPa--15 MPa, and the compression stress of the pre-stress layer 4 is 20 MPa-20 MPa. The optical fiber reduces the fiber loss from the stress, and under this stress distribution, the attenuation value of the optical fiber at 1550 nm wavelength is ≤0.160 db / km, and the single-mode optical fiber of the series such as G.652, G.654.E and the like is produced, and the transmission attenuation value of the optical signal in the optical fiber is reduced. Moreover, germanium element is not used, and the increase of the fiber loss caused by the material of the optical fiber itself is avoided, and the further reduction of the fiber loss is realized.

[0055] Optionally, a coating layer 5 is applied to the outside of the prestressed stress layer 4. The outer diameter of the coating layer 5 is 235μm-255μm, and the material of the coating layer 5 is acrylic resin. The coating layer 5 is used to prevent the optical fiber from being worn by external factors, thus ensuring the operability of the optical fiber. Moreover, in this embodiment, under the combined action of this coating layer 5 and the auxiliary layer 3, the compressive stress optical fiber can produce G.657.B3 series bend-insensitive single-mode optical fibers, with a bending loss of less than 0.15dB for 5mm*10 turns, which greatly improves the bending resistance of the optical fiber and extends its service life. Optionally, the coating layer 5 is a double coating, including an inner coating and an outer coating; or the coating layer 5 is a single coating; or for color-locked optical fibers, the coating layer 5 includes a color-locking layer.

[0056] It should be noted that this embodiment also provides a manufacturing process for compressive stress optical fiber, used to manufacture the compressive stress optical fiber. In addition, this manufacturing process can also produce various types of communication optical fibers, such as single-mode optical fibers, multimode optical fibers, and special optical fibers. The specific steps are as follows:

[0057] S1. Prepare a loose core layer 1;

[0058] In this embodiment, as Figure 2 As shown, a loosely structured core layer 1 containing alkali ions is fabricated using a vapor deposition (VCD) process. The VCD apparatus 10 includes a quartz tube 101, a heating element 102, a three-way valve 103, a gas generating device, and an alkali ion heating chamber 104. The gas generating device and the alkali ion heating chamber 104 are connected to the two inlets of the three-way valve 103, and the quartz tube 101 is connected to the outlet of the three-way valve 103. The gas generating device provides the quartz tube 101 with raw material gases such as silicon tetrachloride, oxygen, and hydrogen. The alkali ion heating chamber 104 contains alkali ion salts and provides alkali ion vapors to the quartz tube 101. The alkali ion salts form alkali ion vapors under process conditions of 1250°C-1400°C. The heating element 102 is located below the quartz tube 101 and provides the necessary heat for the reaction. The raw material gas and alkali ion vapor inside the quartz tube 101 undergo a chemical reaction and deposit to form a loose core layer 1. When the process is nearing completion, the channel of the alkali ion heating box 104 is closed.

[0059] S2. The loose body is removed and vitrified through dehydration and sintering processes. Fluorine ions are incorporated during the sintering process to form an inner cladding layer 2 containing fluorine ions outside the core layer 1. At the same time, alkali ions diffuse within the core layer 1 to form a core rod that combines the core layer 1 and the inner cladding layer 2.

[0060] The incorporation of fluorine element forms a refractive index difference Δ1 between the inner cladding layer 2 and the core layer 1, and Δ1 ≈-0.25% to-0.45%. In addition, the viscosity of quartz glass is high, and the viscosity is reduced after the incorporation of fluorine element. The core layer 1 and the inner cladding layer 2 of the optical fiber are in a high-temperature molten state, and the viscosity is adapted. The inner cladding layer 2 obtains a viscosity value close to that of the core layer 1, and the internal stress of the core layer 1 and the inner cladding layer 2 is changed.

[0061] S3, an auxiliary layer 3 is made outside the core rod.

[0062] In this embodiment, a sleeve containing the auxiliary layer 3 containing halogen element is made, and the auxiliary layer 3 is sleeved outside the inner cladding layer 2 by using the sleeve method.

[0063] The incorporation of halogen element reduces the refractive index of the auxiliary layer 3. By using a comprehensive waveguide design, a refractive index difference Δ2 between the auxiliary layer 3 and the inner cladding layer 2 is formed, and Δ2 ≈-0.5% to-1.2%. When the incident light is transmitted in the compression stress optical fiber, the total reflection condition is formed under the conditions of the refractive index difference Δ1 and the refractive index difference Δ2, and the transmission loss of the incident light in the compression stress optical fiber is reduced. On the other hand, the incorporation of halogen element further improves the bending resistance of the optical fiber, and the macro-bending level of the optical fiber is obviously improved. In addition, the addition of halogen element forms a large relative stress at the interface between the inner cladding layer 2 and the auxiliary layer 3.

[0064] S4, a pre-stress layer 4 is made outside the auxiliary layer 3.

[0065] In this embodiment, a sleeve containing the pre-stress layer 4 containing aluminum ions is made, and the pre-stress layer 4 is sleeved outside the auxiliary layer 3 by using the sleeve method.

[0066] In other embodiments, a plasma spraying method can also be used to prepare the pre-stress layer 4 containing aluminum ions outside the auxiliary layer 3.

[0067] S5, the combination of the core layer 1, the inner cladding layer 2, the auxiliary layer 3 and the pre-stress layer 4 is subjected to a drawing process.

[0068] S6, a coating layer 5 is made outside the pre-stress layer 4.

[0069] In this embodiment, a coating mold is used to make the coating layer 5 outside the pre-stress layer 4 to enhance the structural strength of the optical fiber and make the optical fiber operable.

[0070] Note that the above merely describes preferred embodiments of the application and the principles of the application. It will be understood by those skilled in the art that the application is not limited to the specific embodiments described herein, and that changes, modifications and substitutions can be made by those skilled in the art without departing from the scope of the application. Therefore, although the application has been described in detail by the above embodiments, the application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the application, and the scope of the application is determined by the appended claims.

Claims

1. A compressive stress optical fiber, comprising: The core layer (1) is made of silicon dioxide containing alkali ions, wherein the weight content of the alkali ions is 200ppm to 400ppm based on the total weight of the core layer (1). The inner cladding layer (2) covers the core layer (1), and the material of the inner cladding layer (2) is silicon dioxide containing fluoride ions, wherein the weight content of the fluoride ions is 5000ppm-10000ppm based on the total weight of the inner cladding layer (2). An auxiliary layer (3) is wrapped around the inner cladding layer (2). The auxiliary layer (3) is made of silicon dioxide containing halide ions, wherein the weight content of the halide ions is 13,000 ppm to 20,000 ppm based on the total weight of the auxiliary layer (3). A prestress layer (4) is wrapped around the auxiliary layer (3). The material of the prestress layer (4) is silicon dioxide containing aluminum ions, wherein the weight content of the aluminum ions is 5ppm to 20ppm based on the total weight of the prestress layer (4). The optical fiber has an attenuation of ≤0.160 dB / km at a wavelength of 1550 nm; The compressive stress of the core layer and the inner cladding layer is -40MPa to -20MPa, the compressive stress of the auxiliary layer is -35MPa to -15MPa, and the tensile stress of the prestressed layer is 20MPa.

2. The compressive stress optical fiber according to claim 1, wherein, The outer diameter of the core layer (1) is 9μm~13μm; The outer diameter of the inner cladding (2) is 20 μm to 40 μm; The outer diameter of the auxiliary layer (3) is 70μm~90μm; The outer diameter of the prestressed layer (4) is 125μm-126μm.

3. The compressive stress optical fiber according to claim 1, wherein, The refractive index difference between the inner cladding (2) and the core layer (1) is approximately -0.25% to -0.45%. The refractive index difference between the auxiliary layer (3) and the core layer (1) is Δ2≈-0.5%~-1.2%.

4. The compressive stress optical fiber according to claim 1 further includes a coating layer (5), the coating layer (5) covering the prestress layer (4), and the material of the coating layer (5) is an acrylic resin.

5. The compressive stress optical fiber according to claim 4, wherein the outer diameter of the coating layer (5) is 235μm-255μm.

6. The compressive stress optical fiber according to claim 1, wherein, The alkali ions in the core layer (1) are in the form of oxides of doped alkali ions, including K2O or Li2O. The aluminum ions in the prestressed stress layer (4) are in the form of oxides of aluminum ions, including Al2O3.

7. The compressive stress optical fiber according to claim 4, wherein, The coating layer (5) is a double coating layer, including an inner coating layer and an outer coating layer; or the coating layer (5) is a single coating layer.

8. A manufacturing process for a compressive stress optical fiber, used to manufacture the compressive stress optical fiber as described in any one of claims 1-7, comprising the following steps: S1. Prepare the core layer (1) in the form of a loose body; S2. Take out the loose body and vitrify it through dehydration and sintering processes to form a core rod that combines the core layer (1) and the inner cladding layer (2); S3. The auxiliary layer (3) is fabricated on the outside of the mandrel. S4. The prestressed layer (4) is made outside the auxiliary layer (3); S5. The assembly of the core layer (1), the inner cladding layer (2), the auxiliary layer (3) and the prestressed layer (4) is subjected to wire drawing.

9. The manufacturing process of the compressive stress optical fiber according to claim 8, wherein, After step S5, step S6 is also included, in which a coating layer (5) is formed on the outside of the prestressed stress layer (4).

10. The manufacturing process of the compressive stress optical fiber according to claim 9, wherein, In step S1, the core layer (1) containing the alkali ions and in a loose state is fabricated by a vapor deposition process. In step S2, fluoride ions are incorporated during the sintering process, and the alkali ions diffuse within the core layer (1) to form an inner cladding (2) containing the fluoride ions outside the core layer (1). In step S3, a sleeve containing the auxiliary layer (3) containing the halide ions is made by using a sleeve method to fit the auxiliary layer (3) onto the outside of the inner cladding (2). In step S4, a sleeve containing the prestressed stress layer (4) is made by using a sleeve method to fit the prestressed stress layer (4) onto the outside of the auxiliary layer (3). In step S6, a coating layer (5) is made on the outside of the prestressed stress layer (4) using a coating mold.

11. The manufacturing process of the compressive stress optical fiber according to claim 8, wherein, In step S4, the prestress layer (4) containing the aluminum ions is prepared on the outside of the auxiliary layer (3) by plasma spraying.

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