A method of optical fiber production

Abstract

The application discloses a kind of optical fiber preparation methods, including selecting size matching core layer glass rod and cladding glass tube;Assembling combination optical fiber drawing clamp, realize the relative fixation between core layer glass rod and cladding glass tube by optical fiber drawing clamp, form optical fiber preform;The upper end of optical fiber preform is connected with rod feeding device, and the lower end of optical fiber preform is fed into heating device;Form embryo stick after the lower end of optical fiber preform is heated, embryo stick is fed into traction device, and negative pressure device is opened to form negative pressure;Optical fiber preform is stretched under high-temperature negative pressure condition, and the preparation of optical fiber product is completed.The relative fixation of core layer glass rod and cladding glass tube is realized by optical fiber drawing clamp, the step of high-temperature melting shrinkage forming is eliminated, the preparation difficulty and production cost are reduced, and it is suitable for different specifications of optical fiber preform.Simultaneously, the gap between core layer glass rod and cladding glass tube is vacuumized to strengthen the adhesion between the two, and the strength of optical fiber is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical fiber manufacturing, and in particular to an optical fiber preparation method. BACKGROUND

[0002] An optical fiber is composed of a high-refractive-index core glass rod and a low-refractive-index cladding glass tube. In the current optical fiber product manufacturing process, the core glass rod and the cladding glass tube are generally fused together at high temperature to form an optical fiber preform, and then the optical fiber preform is heated and softened for stretching to form an optical fiber product. A Chinese patent application for invention with the publication number CN115650576A discloses a preform preparation method and an optical fiber preparation method. The method melts and shrinks a preform precursor to obtain a preform, and then draws the obtained preform to form an optical fiber. However, in the process of melting and shaping the optical fiber preform, the optical fiber product is prone to produce bubbles or air lines. The process of melting and shaping the optical fiber preform also has the problems of high cost and high scrap rate.

[0003] In addition, with the fierce competition in the industry, more and more manufacturers tend to increase the size of the optical fiber preform to reduce the manufacturing cost of the optical fiber. Due to the low thermal conductivity of glass, the large-size optical fiber preform has the problem of difficulty in forming due to the large difference between the center viscosity and the edge viscosity in the melting process. SUMMARY

[0004] To solve at least one of the above technical problems, the present application provides an optical fiber preparation method, which adopts the following technical solutions:

[0005] The optical fiber preparation method provided by the present application comprises:

[0006] selecting a core glass rod and a cladding glass tube with matching sizes;

[0007] assembling an optical fiber drawing clamp, and realizing the relative fixation between the core glass rod and the cladding glass tube through the optical fiber drawing clamp to form an optical fiber preform;

[0008] connecting the upper end of the optical fiber preform with a rod feeding device, and feeding the lower end of the optical fiber preform into a heating device;

[0009] heating the lower end of the optical fiber preform to form a blank rod, feeding the blank rod into a pulling device, and starting a negative pressure device to form a negative pressure;

[0010] stretching the optical fiber preform under high-temperature and negative pressure conditions to complete the preparation of the optical fiber product.

[0011] In some embodiments of the present application, the stretching of the optical fiber preform under high-temperature and negative pressure conditions comprises:

[0012] determining the pulling speed of the pulling device according to the rod feeding speed of the rod feeding device and the diameter of the prepared optical fiber product.

[0013] or,

[0014] The rod feeding speed of the rod feeding device is determined according to the pulling speed of the pulling device and the diameter of the optical fiber product.

[0015] In some embodiments of the present application, the pulling speed, the rod feeding speed, the diameter of the optical fiber product and the diameter of the optical fiber preform satisfy the following relationship:

[0016] V1 = V2 * D 2 / d 2

[0017] Wherein, V1 is the pulling speed, V2 is the rod feeding speed, D is the diameter of the optical fiber preform and d is the diameter of the optical fiber product.

[0018] In some embodiments of the present application, the step of selecting the core glass rod and the cladding glass tube with matched sizes specifically comprises that the outer diameter of the core glass rod is 0.5-1.5 mm smaller than the inner diameter of the cladding glass tube.

[0019] In some embodiments of the present application, the step of selecting the core glass rod and the cladding glass tube with matched sizes specifically comprises that the length of the cladding glass tube is 50-100 mm longer than the length of the core glass rod.

[0020] In some embodiments of the present application, the step of assembling the optical fiber drawing clamp to fix the core glass rod and the cladding glass tube relative to each other to form the optical fiber preform, wherein the length of the cladding glass tube is longer than the length of the core glass rod.

[0021] In some embodiments of the present application, the step of connecting the upper end of the optical fiber preform with the rod feeding device and feeding the lower end of the optical fiber preform into the heating device further comprises determining the processing temperature of the heating device according to the softening temperature of the cladding glass tube.

[0022] In some embodiments of the present application, the step of heating the lower end of the optical fiber preform to form a preform and feeding the preform into the pulling device and opening the negative pressure device to form a negative pressure further comprises:

[0023] The cladding glass tube at the lower end of the optical fiber preform is in the high-temperature zone of the heating device and softens and shrinks to fall to form a preform;

[0024] The falling cladding glass tube is fed into the pulling device to seal the lower end of the preform;

[0025] The negative pressure device is opened to extract the air between the core glass rod and the cladding glass tube to form a negative pressure, and the negative pressure value is at least -0.08 MPa.

[0026] In some embodiments of the present invention, the optical fiber drawing fixture includes:

[0027] A connector is connected to a bar feeding device, and a fastener is detachably installed at the bottom end of the connector.

[0028] Positioning component, which is detachably connected to the fastener, and is connected to the core glass rod;

[0029] The clamping assembly includes two semi-ring structures that are connected relative to each other to form a ring.

[0030] The cladding glass tube is installed between the fastener and the clamping assembly, and the core glass rod is fixed inside the cladding glass tube by a positioning component.

[0031] In some embodiments of the present invention, the step of assembling and combining optical fiber drawing fixtures to fix the core glass rod and cladding glass tube to form an optical fiber preform specifically includes:

[0032] A positioning groove is machined on the cylindrical surface at the end where the core glass rod connects to the rod feeding device;

[0033] The connectors, fasteners and positioning components are assembled from top to bottom, and the core glass rod is connected to the positioning component by a steel rope.

[0034] The cladding glass tube is fitted over the core glass rod from bottom to top, so that the inner wall of the cladding glass tube abuts against the outer wall of the fastener.

[0035] Two semi-ring structures are fitted onto the joint between the fastener and the cladding glass tube, so that the inner wall of the semi-ring structure abuts against the outer wall of the cladding glass tube, thus fixing the two semi-ring structures and forming an optical fiber preform.

[0036] The embodiments of the present invention have at least the following beneficial effects: The present invention achieves relative fixation between the core glass rod and the cladding glass tube through an optical fiber drawing clamp, eliminating the need for the high-temperature melting and shrinking molding of the preform, thus reducing the manufacturing difficulty; simultaneously, vacuuming the gap between the core glass rod and the cladding glass tube strengthens their adhesion and improves the strength of the optical fiber. The method provided by the present invention is applicable to optical fiber preforms of different specifications, reducing the cost of optical fiber production. Attached Figure Description

[0037] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0038] Fig. 1 This is a schematic diagram illustrating the steps of an optical fiber fabrication method.

[0039] Fig. 2 This is a schematic diagram of the optical fiber drawing fixture.

[0040] Fig. 3 This is a schematic diagram of the structure of an optical fiber preform;

[0041] Fig. 4 A schematic diagram of optical fiber fabrication.

[0042] Reference numerals: 100, fiber optic drawing clamp; 110, connector; 120, clamping assembly; 121, semi-ring structure; 1211, stepped portion; 122, threaded fastener; 130, positioning component; 140, fastener; 200, core glass rod; 201, positioning groove; 300, cladding glass tube. Detailed Implementation

[0043] The following is combined Figs. 1 to 4 Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0044] In the description of this invention, it should be understood that the terms "center," "middle," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Features defined with "first" and "second" are used to distinguish feature names and do not have special meanings. Furthermore, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0045] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0046] Optical fibers consist of a high-refractive-index core glass rod and a low-refractive-index cladding glass tube. In current optical fiber manufacturing processes, the core glass rod and cladding glass tube are typically fused together at high temperatures to form an optical fiber preform. This preform is then heated and softened before being stretched to form the final optical fiber. However, during the molten preform preparation and subsequent heating and stretching operations, air bubbles or air lines are prone to form in the optical fiber. Furthermore, the process of forming optical fiber preforms also suffers from high costs and a high scrap rate.

[0047] Furthermore, with intensifying industry competition, more and more manufacturers are inclined to increase the size of optical fiber preforms to reduce the manufacturing cost of optical fibers. Due to the low thermal conductivity of glass, large-size optical fiber preforms face the problem of excessive viscosity difference between the center and the edge during the melting and fabrication process, making them difficult to form.

[0048] The optical fiber fabrication method provided by this invention relates to an optical fiber drawing fixture 100. Specifically, the optical fiber drawing fixture 100 includes a connector 110, a clamping assembly 120, and a positioning member 130. The connector 110 is connected to a rod feeding device. The clamping assembly 120 is fixed relative to the connector 110 and includes two semi-ring structures 121, which are detachably connected relative to each other to form a ring. The positioning member 130 is fixedly connected to the connector 110 and is used to position the core glass rod 200. The cladding glass tube 300 is installed between the connector 110 and the clamping assembly 120, and the core glass rod 200 is fixed inside the cladding glass tube 300 by the positioning member 130. The fiber drawing fixture 100 uses a clamping assembly 120 to fix the cladding glass tube 300 and a positioning element 130 to fix the core glass rod 200. A mechanical structure achieves the connection and fixation between the core glass rod 200 and the cladding glass tube 300, enabling subsequent fiber drawing steps. By adjusting the dimensions of the clamping assembly 120, the fiber drawing fixture 100 can produce preforms of various specifications, reducing the difficulty and cost of fiber preform forming.

[0049] Specifically, the fiber drawing fixture 100 also includes a fastener 140, which is fixedly connected to the connector 110. The cladding glass tube 300 is installed between the fastener 140 and the clamping assembly 120. Referring to the accompanying drawings, in this embodiment, the fastener 140 is detachably installed at the bottom of the connector 110. Specifically, the fastener 140 extends into the cladding glass tube 300, so that the outer wall of the fastener 140 abuts against the outer wall of the cladding glass tube 300 to achieve a seal at the upper end of the cladding glass tube 300, while providing sufficient clamping force for subsequent drawing operations. Specifically, the fastener 140 is provided with an externally threaded rod, and the connector 110 is provided with a corresponding internally threaded hole to achieve a detachable connection between the fastener 140 and the connector 110.

[0050] Specifically, the fastener 140 has a circumferentially arranged first sealing surface, and the clamping assembly 120 has a second mounting surface corresponding to the first sealing surface. The first sealing surface and the second mounting surface form an annular mounting cavity. It is understood that the cladding glass tube 300 is installed within the annular mounting cavity to achieve relative fixation between the cladding glass tube 300 and the fiber drawing fixture 100. Specifically, the inner wall of the cladding glass tube 300 mates with the first sealing surface to ensure a sealing effect at the upper end of the cladding glass tube 300, preventing defects such as bubbles or air lines from appearing in the subsequent fiber drawing process. The outer wall of the cladding glass tube 300 mates with the second mounting surface to tighten the cladding glass tube 300, ensuring a tight contact with the fastener 140.

[0051] Furthermore, referring to the accompanying drawings, the first sealing surface is a conical structure with a larger upper surface and a smaller lower surface, while the second mounting surface is a cylindrical structure. It can be understood that the width of the annular mounting cavity varies at different heights, accommodating the fixing of clad glass tubes 300 of different diameters. Specifically, the width of the annular mounting cavity gradually decreases towards the connector 110. Cladding glass tubes 300 of different specifications are fixed at different heights within the annular mounting cavity. By adjusting the taper of the first sealing surface, the processing range of the clad glass tubes 300 applicable to the fiber optic drawing fixture 100 can be adjusted. In some embodiments, to ensure a tight connection between the fastener 140 and the clad glass tube 300, PTFE tape is wrapped around the joint for further sealing.

[0052] It is understandable that, in order to fix the cladding glass tube 300, in other embodiments, the first sealing surface is a cylindrical structure and the second mounting surface is a conical structure with a smaller top and a larger bottom, achieving the same effect. In other embodiments, both the first sealing surface and the second mounting surface are set as cylindrical structures to fix cladding glass tubes 300 of specific specifications.

[0053] Specifically, the positioning element 130 is fixedly connected to the connecting element 110 via a fastener 140, and the positioning element 130 and the fastener 140 are detachably connected. In this embodiment, the fastener 140 has an internal threaded hole for connecting the positioning element 130, and the positioning element 130 is provided with a corresponding external threaded rod. The positioning element 130 achieves relative fixation between itself and the connecting element 110 through the threaded connection with the fastener 140. Referring to the accompanying drawings, the positioning element 130 is configured as a hook, and the hook is used to hook the core glass rod 200 via a steel rope to achieve relative fixation between the connecting element 110 and the core glass rod 200.

[0054] Specifically, the connector 110 has a first vent hole, and the fastener 140 has a second vent hole, with the first and second vent holes communicating with each other. It can be understood that the cladding glass tube 300 can be connected to the negative pressure system through the first and second vent holes, maintaining a negative pressure state between the cladding glass tube 300 and the core glass rod 200 during the fiber drawing process, further securing the relative fixation between the core glass rod 200 and the cladding glass tube 300, and improving the product quality of subsequent optical fiber drawing. Referring to the accompanying drawings, in this embodiment, the connector 110 is a rod-shaped structure, and the first and second vent holes are coaxially arranged with the rod-shaped structure to facilitate the negative pressure system extracting air from the cladding glass tube 300.

[0055] Specifically, a sealing structure is provided at one end of the semi-ring structure 121 near the connector 110. This sealing structure abuts against the fastener 140 to further enhance the sealing effect at the upper end of the cladding glass tube 300, preventing air from entering during fiber drawing and causing defects such as air bubbles or air lines in the product. Referring to the attached drawings, the sealing structure is configured as an inwardly extending stepped portion 1211 protruding from the second mounting surface. Both stepped portions 1211 abut against each other and also against the upper end of the fastener 140 to prevent air from entering the cladding glass tube 300 and ensure a negative pressure effect. It can be understood that during fiber drawing, the sealing structure can also prevent relative sliding between the fastener 140 and the clamping assembly 120 by abutting against the fastener 140, ensuring the relative fixation between the core glass rod 200 and the cladding glass tube 300.

[0056] Furthermore, the clamping assembly 120 also includes a threaded fastener 122. It can be understood that the two semi-ring structures 121 are connected by the threaded fastener 122 to facilitate the assembly and disassembly of the clamping assembly 120 while ensuring a secure connection. In other embodiments, the two semi-ring structures 121 can also be connected by snap-fit ​​or plug-in connections to form a ring.

[0057] In some embodiments, to flexibly adjust the clamping effect of the clamping assembly 120 on the cladding glass tube 300, an adjustment gap is provided between the two semi-ring structures 121. The size of the adjustment gap is changed by rotating the threaded fastener 122 to adjust the clamping effect of the clamping assembly 120 on the cladding glass tube 300. Specifically, to allow for the adjustment gap, in some embodiments, the diameter of the second mounting surface is smaller than the outer diameter of the cladding glass tube 300; in other embodiments, the angle corresponding to the semi-ring structure 121 is set to be less than 180°.

[0058] This invention also relates to an optical fiber preform, which includes the aforementioned optical fiber drawing clamp 100, cladding glass tube 300, and core glass rod 200. A clamping assembly 120 clamps the cladding glass tube 300. The core glass rod 200 is provided with a positioning structure corresponding to the positioning element 130, and the core glass rod 200 is connected to the positioning element 130 through the positioning structure. It can be understood that in the optical fiber preform, the core glass rod 200 and the cladding glass tube 300 are relatively fixed by being connected through the optical fiber drawing clamp 100, without the need for bonding by melting or other methods. This is suitable for the fabrication of optical fiber preforms of various diameters, improving the yield rate of optical fiber manufacturing and reducing manufacturing costs.

[0059] Specifically, the positioning structure is configured as a positioning groove 201, which, referring to the accompanying drawings, is formed around the peripheral wall of the core glass rod 200. Specifically, a steel rope is wound around the positioning groove 201, and the steel rope is installed on the positioning member 130 to achieve relative fixation between the core glass rod 200 and the optical fiber drawing clamp 100. It is understood that in some embodiments, an outlet groove is also formed between the positioning groove 201 and the upper end face of the core glass rod 200 to accommodate the steel rope.

[0060] This invention relates to a method for fabricating optical fibers, specifically including:

[0061] S1. Select a core glass rod and cladding glass tube of matching size;

[0062] S2. Assemble the fiber drawing fixture. The fiber drawing fixture is used to fix the core glass rod and the cladding glass tube to form the fiber preform.

[0063] S3. Connect the upper end of the optical fiber preform to the feeding device and feed the lower end of the optical fiber preform into the heating device.

[0064] S4. After the lower end of the optical fiber preform is heated to form a blank rod, the blank rod is sent into the traction device and the negative pressure device is turned on to form negative pressure.

[0065] S5. The optical fiber preform is stretched under high temperature and negative pressure conditions to complete the preparation of the optical fiber product.

[0066] This invention achieves relative fixation between the core glass rod and the cladding glass tube using an optical fiber drawing clamp, eliminating the need for high-temperature melting and shrinking to form the preform, thus reducing manufacturing difficulty. Simultaneously, a vacuum is applied to the gap between the core glass rod and the cladding glass tube to strengthen their adhesion and improve optical fiber strength. The method provided by this invention is applicable to optical fiber preforms of different specifications, reducing optical fiber production costs.

[0067] Optionally, step S1 specifically includes the following steps:

[0068] S11. Determine the diameter and length of the cladding glass tube based on the dimensions of the optical fiber preform;

[0069] S12. Select the core glass rod according to the diameter of the cladding glass tube. The outer diameter of the core glass rod is smaller than the inner diameter of the cladding glass tube, and the difference is limited to the first value range.

[0070] S13. Cut the core glass rod according to the length of the cladding glass tube. The length of the cladding glass tube is longer than the length of the core glass rod, and the difference is limited to the second numerical range.

[0071] It is understood that controlling the relative size between the cladding glass tube and the core glass rod ensures a tight fit, and controlling the relative length between them reduces material waste. In this embodiment, the first numerical range is 0.5–1.5 mm, and the second numerical range is 50–100 mm.

[0072] Optionally, step S2 specifically includes the following steps:

[0073] S21. A positioning groove is machined on the cylindrical surface at the end where the core glass rod connects to the rod feeding device.

[0074] S22. Assemble the connectors, fasteners and positioning components from top to bottom, and connect the core glass rod to the positioning components via steel rope;

[0075] S23. The cladding glass tube is fitted over the core glass rod from bottom to top, so that the inner wall of the cladding glass tube abuts against the outer wall of the fastener.

[0076] S24. Place the two semi-ring structures onto the joint between the fastener and the cladding glass tube, so that the inner wall of the semi-ring structure abuts against the outer wall of the cladding glass tube, and fix the two semi-ring structures to form an optical fiber preform.

[0077] Optionally, when the cladding glass tube is fitted over the core glass rod, both ends of the cladding glass tube are longer than the core glass rod.

[0078] Optionally, step S3 specifically includes the following steps:

[0079] S31. Connect the connector to the rod feeding device, and connect the cladding glass tube to the negative pressure device through the first vent and the second vent.

[0080] S32. Determine the processing temperature of the heating device based on the softening temperature of the cladding glass tube, and send the cladding glass tube at the lower end of the optical fiber preform into the heating device.

[0081] Specifically, in this embodiment, the processing temperature of the heating device is 50-80°C higher than the softening temperature of the cladding glass tube.

[0082] Optionally, step S4 specifically includes the following steps:

[0083] S41. The cladding glass tube at the lower end of the optical fiber preform is in the high-temperature zone of the heating device, softens, shrinks and falls to form a preform.

[0084] S42. Send the falling cladding glass tube into the traction device to seal the lower end of the billet.

[0085] S43. Turn on the negative pressure device to extract the air between the core glass rod and the cladding glass tube to form a negative pressure, so that the negative pressure between the cladding glass tube and the core glass rod is stabilized at the first pressure value.

[0086] In this embodiment, the first pressure value is at least -0.08 MPa.

[0087] Optionally, step S5 specifically includes step S51 or step S52:

[0088] S51. Determine the traction speed of the traction device based on the feeding speed of the feeding device and the diameter of the optical fiber product being prepared.

[0089] S52. Determine the rod feeding speed of the rod feeding device based on the traction speed of the traction device and the diameter of the optical fiber product to be prepared.

[0090] The following relationships exist between the traction speed, the fiber feed speed, the diameter of the optical fiber product, and the diameter of the optical fiber preform:

[0091] V1 = V2 * D 2 / d 2

[0092] Where V1 is the traction speed, V2 is the rod feeding speed, D is the diameter of the optical fiber preform, and d is the diameter of the optical fiber product.

[0093] In the description of this specification, the use of terms such as "an embodiment," "some examples," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples" indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0094] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for fabricating optical fibers, characterized in that, include: Select core glass rods and cladding glass tubes of matching sizes; The fiber drawing fixture is assembled and combined to achieve relative fixation between the core glass rod and the cladding glass tube, forming a fiber preform. Connect the upper end of the optical fiber preform to the feeding device, and feed the lower end of the optical fiber preform into the heating device. The lower end of the optical fiber preform is heated to form a blank rod. The blank rod is then fed into the traction device, and the negative pressure device is activated to create negative pressure. The optical fiber preform is stretched under high temperature and negative pressure conditions to complete the fabrication of optical fiber products; The fiber drawing fixture includes: A connector is connected to a bar feeding device, and a fastener is detachably installed at the bottom end of the connector. Positioning component, which is detachably connected to the fastener, and is connected to the core glass rod; The clamping assembly includes two semi-ring structures that are connected relative to each other to form a ring. The cladding glass tube is installed between the fastener and the clamping assembly, and the core glass rod is fixed inside the cladding glass tube by a positioning component.

2. The optical fiber fabrication method according to claim 1, characterized in that: The stretching of the optical fiber preform under high temperature and negative pressure conditions includes: The traction speed of the traction device is determined based on the feeding speed of the feeding device and the diameter of the optical fiber product being prepared. or, The feeding speed of the rod feeding device is determined based on the traction speed of the traction device and the diameter of the optical fiber product to be prepared.

3. The optical fiber fabrication method according to claim 2, characterized in that: The following relationship exists between traction speed, fiber feed speed, fiber product diameter, and fiber preform diameter: in, For traction speed, For the speed of rod delivery, D The diameter of the optical fiber preform. d The diameter of the optical fiber product.

4. The optical fiber fabrication method according to claim 1, characterized in that: The step of selecting a core glass rod and a cladding glass tube with matching dimensions specifically includes: the outer diameter of the core glass rod is 0.5 to 1.5 mm smaller than the inner diameter of the cladding glass tube.

5. The optical fiber fabrication method according to claim 4, characterized in that: The step of selecting a core glass rod and a cladding glass tube with matching dimensions specifically includes: the length of the cladding glass tube being 50 to 100 millimeters longer than the length of the core glass rod.

6. The optical fiber fabrication method according to claim 5, characterized in that: The assembled fiber drawing fixture is used to fix the core glass rod and the cladding glass tube to form the fiber preform. In this step, both ends of the cladding glass tube are longer than the core glass rod.

7. The optical fiber fabrication method according to claim 1, characterized in that: The step of connecting the upper end of the optical fiber preform to the feeding device and feeding the lower end of the optical fiber preform into the heating device further includes: determining the processing temperature of the heating device based on the softening temperature of the cladding glass tube.

8. The optical fiber fabrication method according to claim 1, characterized in that: The step of heating the lower end of the optical fiber preform to form a blank, feeding the blank into the traction device, and activating the negative pressure device to create negative pressure specifically includes: The cladding glass tube at the lower end of the optical fiber preform is in the high-temperature zone of the heating device, softens, shrinks, and falls to form a preform. The falling cladding glass tube is fed into the traction device to seal the lower end of the billet. Turn on the negative pressure device to extract the air between the core glass rod and the cladding glass tube to create a negative pressure, with a negative pressure value of at least -0.08 MPa.

9. The optical fiber fabrication method according to claim 1, characterized in that: The assembled fiber drawing fixture, which fixes the core glass rod and cladding glass tube to form the fiber preform, specifically includes the following steps: A positioning groove is machined on the cylindrical surface at the end where the core glass rod connects to the rod feeding device; The connectors, fasteners and positioning components are assembled from top to bottom, and the core glass rod is connected to the positioning component by a steel rope. The cladding glass tube is fitted over the core glass rod from bottom to top, so that the inner wall of the cladding glass tube abuts against the outer wall of the fastener. Two semi-ring structures are fitted onto the joint between the fastener and the cladding glass tube, so that the inner wall of the semi-ring structure abuts against the outer wall of the cladding glass tube, thus fixing the two semi-ring structures and forming an optical fiber preform.

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