CN113716862B - Method and apparatus for manufacturing optical fiber - Google Patents

Abstract

The invention provides a method for preparing an optical fiber and a device thereof, and relates to the technical field of optical fibers. Wherein, the preparation method of the optical fiber comprises the following steps: providing an optical fiber preform; melting and drawing the preform to form an optical fiber main body; annealing the optical fiber main body; coating the annealed optical fiber main body to form an inner coating layer and The outer coating layer; curing the coated optical fiber body to form an optical fiber; collecting the optical fiber on a fiber collection tray, and placing the fiber collection tray filled with optical fibers in a nitrogen atmosphere for heat treatment. The optical fiber preparation device includes a rod feeding mechanism, a wire drawing furnace, an annealing device, a coating device, a curing device, a pulling mechanism and a processing cabinet. Place the reel full of optical fibers in a nitrogen atmosphere for heat treatment before screening for optical fiber strength, thereby reducing the number of fiber breaks per 1000km of optical fiber.

Description

Optical fiber preparation method and device thereof

technical field

The invention relates to the field of optical fiber technology, in particular to a method for preparing an optical fiber and a device thereof.

Background technique

With the continuous growth of high bandwidth and high speed requirements of the network, optical fiber is widely used in network wiring as a network transmission medium. The common types of optical fiber are single-mode optical fiber and multi-mode optical fiber. Single-mode fiber refers to a fiber that can only transmit one propagation mode at an operating wavelength. Multimode optical fiber refers to the optical fiber whose working wavelength is multi-mode with its possible propagation modes. Since the transmission mode of multimode optical fiber can reach hundreds, the core diameter of multimode optical fiber is thicker than that of single-mode optical fiber, and the numerical aperture is larger. The light source couples more optical power.

In the related art, during the optical fiber preparation process, the optical fiber is directly sent to the optical fiber screening machine for intensity detection after the optical fiber is filled on the fiber receiving tray.

However, there is a problem that the number of fiber breaks per 1000km is high when the optical fiber is directly sent to the optical fiber screening machine for strength testing after it is filled on the fiber collection tray.

Contents of the invention

The invention provides a method for preparing an optical fiber and a device thereof to solve the problem that the number of fiber breaks per 1000 km of the optical fiber prepared by the existing preparation method is relatively high.

In one aspect, the present invention provides a method for preparing an optical fiber, comprising the following steps:

Provide optical fiber preform;

forming an optical fiber body by melting and drawing the optical fiber preform;

annealing the fiber body;

Coating the annealed optical fiber body to form an inner coating layer and an outer coating layer;

curing the coated optical fiber body to form an optical fiber;

The optical fiber is collected on a fiber collection tray, and the fiber collection tray filled with optical fibers is placed in a nitrogen atmosphere for heat treatment.

Optionally, the purity of nitrogen in the nitrogen atmosphere is greater than or equal to 99.999%, and the heat treatment temperature in the nitrogen atmosphere is 45°C-60°C.

Optionally, the time for heat treatment of the optical fiber on the take-up reel in the nitrogen atmosphere is 4 hours to 24 hours.

Optionally, the material of the inner coating layer and the outer coating layer is acrylic resin; the elastic modulus of the acrylic resin used in the inner coating layer after curing is less than or equal to 1.5Mpa, and the viscosity during coating is 1500mPa·s～3000mPa·s and the elongation at break is greater than or equal to 120%, the coating temperature range is 28℃～60℃, and the coating pressure is 0.1MPa～2MPa;

The elastic modulus of the acrylic resin used in the outer coating layer after curing is greater than or equal to 550Mpa, the viscosity during coating is 1500mPa·s～3500mPa·s and the elongation at break is greater than or equal to 5%, and the coating temperature range is 28℃～60℃, coating pressure is 0.1MPa～2MPa.

Optionally, the maximum radius of the inner coating layer is 72.5 μm to 77.5 μm, the maximum radius of the outer coating layer is 87.5 μm to 92.5 μm, and the thickness value of the inner coating layer is the same as that of the outer coating layer. The ratio of thickness value is 1:0.67～1:1.15.

Optionally, the providing an optical fiber preform specifically includes:

Prepare germanium-doped silicon dioxide powder body by axial vapor deposition method;

Dehydroxylation and sintering the germanium-doped silicon dioxide powder body to make a core rod;

preparing an inner cladding on the outside of the mandrel by an axial vapor deposition method;

preparing a middle cladding outside the inner cladding of the optical fiber preform by chemical vapor deposition;

preparing an outer cladding on the outside of the middle cladding of the optical fiber preform by chemical vapor deposition;

Wherein, the relative refractive index of the core rod relative to the outer cladding is 0.35% to 0.45%; the relative refractive index of the inner cladding relative to the outer cladding is 0; the relative refractive index of the middle cladding relative to the outer cladding The relative refractive index of the layer is -0.1%~0.

On the other hand, the present invention also provides an optical fiber preparation device, including a rod feeding mechanism, a drawing furnace, an annealing device, a coating device, a curing device, a pulling mechanism and a processing cabinet;

The rod feeding mechanism is used to send the optical fiber preform to the drawing furnace;

The drawing furnace is located downstream of the rod feeding mechanism, and is used to heat and melt the preform into a glass state and draw it into a filamentous optical fiber body;

The annealing device is located downstream of the drawing furnace and is used to anneal the optical fiber body;

The coating device is located downstream of the annealing device, and is used for coating the annealed optical fiber body;

The curing device is located downstream of the coating device, and is used to cure the coated optical fiber body to form an optical fiber;

The pulling mechanism is located downstream of the curing device, and is used to collect the optical fiber onto the fiber take-up tray;

The processing cabinet is used for heat-treating the fiber reel filled with optical fibers in a nitrogen atmosphere.

Optionally, a control device for optical fiber drawing tension is also included;

The device for controlling the drawing tension of the optical fiber includes: a drawing tension acquisition module, configured to acquire the current drawing tension of the annealed optical fiber body;

The control module is used for adjusting the drawing speed of the pulling mechanism in a manner of reducing the difference between the current drawing tension and the target drawing tension according to the comparison between the current drawing tension and the target drawing tension.

Optionally, the control module is configured to adjust the wire-drawing speed of the traction mechanism in a manner of reducing the difference between the current wire-drawing tension and the target wire-drawing tension according to the comparison between the current wire-drawing tension and the target wire-drawing tension, specifically including:

If the current drawing tension is greater than the first target drawing tension, then reduce the drawing speed of the traction mechanism;

If the current drawing tension is less than the second target drawing tension, then increase the drawing speed of the pulling mechanism.

Optionally, the first target wire drawing tension is the target wire drawing tension plus 1, and the second target wire drawing tension is the target wire drawing tension minus 1;

Wherein, the target drawing tension is measured by a tensiometer when the optical fiber drawing speed is greater than 1800m/min, the cut-off wavelength of the optical fiber is between 1200nm and 1320nm, and the bending loss standard of the optical fiber meets the G.657A1 standard during the optical fiber preparation process Tension in the fiber body.

The invention provides an optical fiber preparation method and a device thereof. A fiber collection tray filled with optical fibers is placed in a nitrogen atmosphere for heat treatment and then the optical fiber strength is screened, thereby reducing the number of fiber breaks per 1000km of optical fibers.

In addition to the technical problems solved by the embodiments of the present invention described above, the technical features constituting the technical solutions, and the beneficial effects brought by the technical features of these technical solutions, the optical fiber preparation methods and devices provided by the embodiments of the present invention provide Other technical problems that can be solved, other technical features contained in the technical solution, and the beneficial effects brought by these technical features will be further described in detail in the specific implementation manner.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to these drawings without any creative effort.

FIG. 1 is a schematic diagram of a radial cross-sectional structure of an optical fiber preform provided by an embodiment of the present invention;

FIG. 2 is a schematic diagram of a cross-sectional refractive index distribution of an optical fiber preform provided by an embodiment of the present invention;

FIG. 3 is a schematic flowchart of a method for preparing an optical fiber preform provided by an embodiment of the present invention;

4 is a schematic diagram of a radial cross-sectional structure of an optical fiber provided by an embodiment of the present invention;

FIG. 5 is a schematic flow diagram of a method for preparing an optical fiber provided by an embodiment of the present invention;

6 is a schematic structural diagram of an optical fiber preparation device provided by an embodiment of the present invention;

Fig. 7 is a block diagram of a control device for optical fiber drawing tension provided by an embodiment of the present invention.

Reference signs:

1-optical fiber preform; 10-core rod; 20-inner cladding; 30-middle cladding;

40-outer cladding; 50-inner coating; 60-outer coating; 2-optical fiber;

200-rod feeding mechanism; 201-drawing furnace; 202-annealing device; 203-coating device;

204-curing device; 205-traction mechanism; 206-processing cabinet; 207-control device;

2071-drawing tension acquisition module; 2072-control module; 208-tension meter; 209-host computer.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

It should be noted that the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

In the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", "fixation" and other terms should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integrated ; can be mechanically connected, can also be electrically connected or can communicate with each other; can be directly connected, can also be indirectly connected through an intermediary, can be the internal communication of two components or the interaction relationship between two components, unless otherwise specified limit. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

In the present invention, unless otherwise clearly specified and limited, the first feature may be in direct contact with the first feature or the first and second feature may be in direct contact with the second feature through an intermediary. touch. Moreover, "above", "above" and "above" the first feature on the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "beneath" and "beneath" the first feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is less horizontally than the second feature.

In the related art, during the optical fiber preparation process, the optical fiber is directly sent to the optical fiber screening machine for intensity detection after the optical fiber is filled on the fiber receiving tray.

However, there is a problem that the number of fiber breaks per 1000km is high when the optical fiber is directly sent to the optical fiber screening machine for strength testing after it is filled on the fiber collection tray.

In order to solve the above problems, an embodiment of the present invention provides a method for preparing an optical fiber and its device. The reel filled with optical fibers is placed in a nitrogen atmosphere for heat treatment and then the fiber intensity is screened, thereby reducing the number of broken optical fibers per 1000 km. fiber count.

The preparation method and device of the optical fiber provided by the present invention will be described in detail below in conjunction with specific embodiments.

FIG. 1 is a schematic diagram of a radial cross-sectional structure of an optical fiber preform provided by an embodiment of the present invention; FIG. 2 is a schematic diagram of a cross-sectional refractive index distribution of an optical fiber preform provided by an embodiment of the present invention.

As shown in Figures 1 and 2, an embodiment of the present invention provides an optical fiber preform 1, which includes a core rod 10, an inner cladding 20, a middle cladding 30, and an outer cladding 40 from the inside to the outside; the core rod 10 is mainly made of germanium-doped oxide Made of silicon, its relative refractive index relative to the outer cladding 40 of the optical fiber preform 1 is 0.35% to 0.45%; the inner cladding 20 of the optical fiber preform 1 is made of silica, and its relative refractive index is The refractive index of the layer 40 is 0; the middle cladding 30 of the optical fiber preform 1 is mainly made of germanium-doped silica, and its relative refractive index relative to the outer cladding 40 of the optical fiber preform 1 is -0.1% to 0; The outer cladding 40 of the preform 1 is made of silicon dioxide.

Among them, in order to make the relative refractive index of the core rod 10, the inner cladding layer 20, and the outer cladding layer 30 of the optical fiber preform 1 have a step-type distribution, the core rod 10 improves the relative refractive index of the core rod 10 by using germanium-doped silicon dioxide. Refractive index, the middle cladding 30 of the optical fiber preform 1 reduces the refractive index by using fluorine-doped silica.

In an optional embodiment, the optical fiber preform 1 includes a core rod 10, an inner cladding 20, a middle cladding 30, and an outer cladding 40 from the inside to the outside; the core rod 10 is mainly made of germanium-doped silica, which is relatively The relative refractive index of the outer cladding 40 of the optical fiber preform 1 is 0.35%; the inner cladding 20 of the optical fiber preform 1 is made of silica, and its relative refractive index relative to the outer cladding 40 of the optical fiber preform 1 is 0; The middle cladding 30 of the optical fiber preform 1 is mainly made of germanium-doped silica, and its relative refractive index relative to the outer cladding 40 of the optical fiber preform 1 is -0.1%; the outer cladding 40 of the optical fiber preform 1 is made of silica Made of silicon.

It should be noted that, as shown in FIG. 2, the radius of the core rod 10 is r1, the radius of the inner cladding 20 of the optical fiber preform 1 is r2, the radius of the middle cladding 30 of the optical fiber preform 1 is r3, and the radius of the optical fiber preform 1 The radius of the outer cladding 40 is r4.

Fig. 3 is a schematic flowchart of a method for preparing an optical fiber preform provided by an embodiment of the present invention.

As shown in FIG. 3, an embodiment of the present invention provides a method for preparing an optical fiber preform 1, including the following steps:

Step S10: Prepare germanium-doped silicon dioxide powder body by axial vapor deposition method.

Step S20: Dehydroxylation and sintering the germanium-doped silicon dioxide powder body to make the core rod 10 .

Specifically, the germanium-doped silica powder is placed in a dehydroxylation atmosphere to remove moisture and hydroxyl groups. The dehydroxylation atmosphere includes carrier gas and fluorine-containing gas. The carrier gas is chlorine gas, and the volume ratio of fluorine-containing gas to chlorine gas is 1:9. ~1:35, the temperature range of the dehydroxylation atmosphere is 800°C to 1100°C, and the germanium-doped silica powder is placed in the dehydroxylation atmosphere for 1 hour to 40 hours.

The relative refractive index of the core rod 10 relative to the outer cladding 40 of the optical fiber preform 1 is 0.35%-0.45% by adding germanium to the silicon dioxide. For example, the core rod 10 is germanium-doped silica with a relative refractive index of 0.35% relative to the outer cladding 40 of the optical fiber preform 1 .

Step S30: Prepare the inner cladding 20 of the optical fiber preform 1 on the outer side of the core rod by the axial vapor deposition method.

Wherein, the inner cladding 20 of the optical fiber preform 1 is made of silicon dioxide.

Step S40: Prepare the middle cladding 30 of the optical fiber preform 1 outside the inner cladding 20 of the optical fiber preform 1 by chemical vapor deposition.

The adjustment of the refractive index of the middle cladding 30 relative to the outer cladding 40 of the optical fiber preform 1 is realized by adding fluorine to the silica. Wherein, the middle cladding 30 of the optical fiber preform 1 is mainly made of germanium-doped silica, and its relative refractive index relative to the outer cladding 40 of the optical fiber preform 1 is -0.1%~0. Preferably, the middle cladding 30 of the optical fiber preform 1 is mainly made of germanium-doped silica, and its relative refractive index relative to the outer cladding 40 of the optical fiber preform 1 is -0.1%.

Step S50: Prepare the outer cladding 40 of the optical fiber preform 1 outside the middle cladding 30 by external chemical vapor deposition.

Wherein, the outer cladding 40 of the optical fiber preform 1 is mainly made of silica.

Fig. 4 is a schematic diagram of a radial cross-sectional structure of an optical fiber provided by an embodiment of the present invention.

As shown in FIG. 4 , the embodiment of the present invention also provides an optical fiber 2 , which includes a core 101 , an inner cladding 20 , a middle cladding 30 , an outer cladding 40 , an inner coating 50 and an outer coating 60 from inside to outside. The core 101 is mainly made of germanium-doped silica, and its relative refractive index relative to the outer cladding 40 of the optical fiber 2 is 0.35% to 0.45%; the inner cladding 20 of the optical fiber 2 is made of silica, and its relative refractive index relative to the optical fiber 2 is The relative refractive index of the outer cladding 40 of the optical fiber 2 is 0; the middle cladding 30 of the optical fiber 2 is mainly made of germanium-doped silica, and its relative refractive index relative to the outer cladding 40 of the optical fiber 2 is -0.1% to 0; The outer cladding 40 of 2 is made of silicon dioxide.

Wherein, the optical fiber 2 is formed by drawing and coating the optical fiber preform 1 by using a drawing furnace.

The relative refractive index distribution of the core 101 , the inner cladding 20 , and the middle cladding 30 of the optical fiber 2 and the outer cladding 40 is stepped, so as to prevent light from overflowing from the core 101 and improve the bending resistance of the optical fiber 2 .

Optionally, the maximum radius of the core 101 is 4 μm to 5 μm, the maximum radius of the inner cladding 20 of the optical fiber 2 is 7.5 μm to 12 μm, the maximum radius of the inner cladding 20 of the optical fiber 2 is 7.5 μm to 12 μm, and the middle cladding of the optical fiber 2 The maximum radius of the layer 30 is 8 μm to 13.5 μm, the maximum radius of the outer cladding layer 40 of the optical fiber 2 is 62 μm to 63 μm, the maximum radius of the inner coating layer 50 is 72.5 μm to 77.5 μm, and the maximum radius of the outer coating layer 60 is 87.5 μm to 87.5 μm. 92.5 μm.

Most of the outer coating layers 60 of existing optical fibers have a radius of 125 μm. The radius of the outer coating layer 60 of the optical fiber 2 of the present application is reduced to 87.5 μm to 92.5 μm, and the relative refractive index of the outer cladding 40 through the core 101, inner cladding 20, and middle cladding 30 of the optical fiber 2 is distributed in a step type to ensure that The bending resistance of the optical fiber 2 makes the optical fiber 2 thinner, thereby increasing the fiber capacity of the pipeline.

It should be noted that the transmission loss per kilometer at a wavelength of 1550 nm is less than or equal to 0.45 dB under the condition of a single turn of the optical fiber 2 with a smaller size and better bending resistance provided by the present application with a radius of 10 mm.

Optionally, the thickness ratio of the inner coating layer 50 to the outer coating layer 60 ranges from 1:0.67 to 1:1.15.

Wherein, the materials of the inner coating layer 50 and the outer coating layer 60 are acrylic resins; the elastic modulus of the acrylic resin used in the inner coating layer 50 is less than or equal to 1.5Mpa after curing, and the acrylic resin used in the inner coating layer 50 The viscosity during coating is 1500mPa·s～3000mPa·s, the elongation at break of the acrylic resin used in the inner coating layer 50 is greater than or equal to 120%, the coating temperature range is 28°C-60°C, and the coating pressure is 0.1MPa～2MPa; the cured elastic modulus of the acrylic resin used in the outer coating layer 60 is greater than or equal to 550Mpa, and the viscosity of the acrylic resin used in the outer coating layer 60 is 1500mPa·s～3500mPa·s during coating. The elongation at break of the acrylic resin used in the coating layer 60 is greater than or equal to 5%, the coating temperature ranges from 28° C. to 60° C., and the coating pressure ranges from 0.1 MPa to 2 MPa.

Through the thickness ratio of the inner coating layer 50 to the outer coating layer 60 ranging from 1:0.67 to 1:1.15, when the radius of the outer coating layer 60 of the optical fiber 2 drops below 92.5 μm, the resistance of the optical fiber 2 can be improved. bending properties.

Fig. 5 is a schematic flowchart of a method for preparing an optical fiber provided by an embodiment of the present invention.

As shown in Figure 5, an embodiment of the present invention provides a method for preparing an optical fiber, including the following steps:

Step S100: providing an optical fiber preform 1.

Wherein, the structure of the optical fiber preform 1 may be the same as that of the above-mentioned optical fiber preform. In other embodiments, the structure of the optical fiber preform can also be selected to be different from the above-mentioned optical fiber preform, and no specific setting is made here.

Step S110: melting and drawing the optical fiber preform 1 to form an optical fiber body.

Specifically, the optical fiber preform 1 is melted in a drawing furnace and drawn into an optical fiber body. The temperature in the drawing furnace is 1800° C. to 2200° C., and the drawing furnace is filled with protective gas.

In order to ensure the stability of heat transfer from the drawing furnace to the optical fiber preform 1 , the gap between the optical fiber preform 1 and the inner wall of the drawing furnace is 5 mm to 15 mm.

It should be noted that the optical fiber body includes the core 101 of the optical fiber 2 , the inner cladding 20 , the middle cladding 30 and the outer cladding 40 .

It should also be pointed out that the protective gas in the drawing furnace is one or more of helium and argon.

Step S120: annealing the fiber body.

Specifically, the fiber body is cooled in the annealing device, the residence time of the fiber body in the annealing device is 0.067s-0.3s, and the temperature in the annealing device is 1400°C-1700°C.

It should be pointed out that the annealing device includes multiple holding furnaces, the multiple holding furnaces are arranged sequentially from top to bottom, and the temperature gradients of the multiple holding furnaces are sequentially arranged from top to bottom.

Step S130: Coating the annealed optical fiber body to form an inner coating layer 50 and an outer coating layer 60 .

Wherein, the inner coating layer 50 and the outer coating layer 60 are made of acrylic resin, the elastic modulus of the acrylic resin used in the inner coating layer 50 is less than or equal to 1.5Mpa after curing, and the acrylic resin used in the inner coating layer 50 The viscosity at the time of coating is 1500mPa·s～3000mPa·s, the elongation at break of the acrylic resin used in the inner coating layer 50 is greater than or equal to 120%; the elastic modulus of the acrylic resin used in the outer coating layer 60 after curing greater than or equal to 550Mpa, the viscosity of the acrylic resin used in the outer coating layer 60 during coating is 1500mPa·s-3500mPa·s, and the elongation at break of the acrylic resin used in the outer coating layer 60 is greater than or equal to 5%.

It should be noted that the inner coating layer 50 uses acrylic resin with a viscosity of 3500mPa·s-7500mPa·s at 25°C, a coating temperature range of 28°C-60°C, and a coating pressure of 0.1MPa-2MPa; The coating layer 60 is made of acrylic resin with a viscosity of 3500mPa·s-7500mPa·s at 25°C, a coating temperature range of 28°C-60°C, and a coating pressure of 0.1MPa-2MPa.

It should also be pointed out that the maximum radius of the inner coating layer 50 is 72.5 μm to 77.5 μm, the maximum radius of the outer coating layer 60 is 87.5 μm to 92.5 μm, and the thickness ratio of the inner coating layer 50 to the outer coating layer 60 ranges from 1: between 0.67 and 1: 1.15.

Step S140: curing the coated optical fiber body to form an optical fiber 2.

Specifically, the coated optical fiber body is formed into an optical fiber 2 in a curing furnace, and one or more of nitrogen, helium, and argon are used for insulation in the curing furnace, and the oxygen concentration in the curing furnace is less than 50 ppm.

Among them, the curing furnaces are arranged sequentially from top to bottom, and the gas volume of each curing furnace is 10L-15L.

Step S150: Collect the optical fiber 2 on the fiber collection tray, and place the fiber collection tray filled with the optical fiber 2 in a nitrogen atmosphere for heat treatment.

Wherein, the optical fiber 2 collects the cured optical fiber 2 onto the fiber collection tray through the pulling mechanism.

The fiber collection tray full of optical fibers 2 is placed in the processing cabinet 206 for heat treatment, and the storage time of the fiber collection tray full of optical fibers 2 in the processing cabinet ranges from 4 hours to 24 hours.

It should be pointed out that when the treatment cabinet 206 is used, it is first vacuumized, and the treatment cabinet 206 is evacuated to 0.015Mpa, and then filled with nitrogen in the treatment cabinet 206. The purity of nitrogen is greater than or equal to 99.999%. The concentration of oxygen in the treatment cabinet 206 Not more than 100ppm, the temperature range in the processing cabinet 206 is 45°C to 60°C.

The optical fiber 2 was prepared by the optical fiber preparation method of the present application, and the fiber drawing speed was equal to 1800m/min, and three types of optical fibers 2 with different maximum diameters of the outer coating layer 60 were obtained. The technical parameters are shown in Table 1.

Table 1 Technical parameters of different fiber implementation cases

The maximum diameter of the outer coating layer is reduced to 175 μm to 185 μm, and the bending resistance of the optical fiber 2 prepared under the optical fiber preparation method of the present application at an optical fiber drawing speed of 1800 m/min can still meet ITU-TG.657A1 Fiber Standard.

Fig. 6 is a schematic structural diagram of an optical fiber preparation device provided by an embodiment of the present invention.

As shown in FIG. 6 , the embodiment of the present invention also provides an optical fiber preparation device, including a rod feeding mechanism 200 , a drawing furnace 201 , an annealing device 202 , a coating device 203 , a curing device 204 , a pulling mechanism 205 and a processing cabinet 206 .

Wherein, the rod feeding mechanism 200 is used to send the optical fiber preform to the drawing furnace 201 . The rod feeding mechanism 200 includes a rod feeding motor, a driving wheel, a driven wheel, a crawler belt, a rod feeding platform that can move up and down, and a clamping piece, and the clamping piece is used to clamp the optical fiber preform; the crawler belt is installed on the driving wheel and the driven wheel, The rod feeding motor is connected with the driving wheel, the rod feeding platform is installed on the crawler, the clamping part is installed on the rod feeding platform, the rod feeding mechanism, the crawler is installed on the driving wheel and the driven wheel, the rod feeding motor is connected with the driving wheel, and the rod feeding The platform is installed on the crawler belt, the moving part can be moved left and right and installed on the rod feeding platform, and the clamping part can be moved forward and backward and installed on the moving part.

The drawing furnace 201 is located downstream of the rod feeding mechanism 200, and is used to heat and melt the optical fiber preform into a glass state and draw it into a filamentous optical fiber body.

The temperature in the wire drawing furnace 201 is 1800°C-2200°C, and the wire drawing furnace 201 is filled with protective gas. The protective gas in the drawing furnace is one or more of helium and argon.

In order to ensure the stability of heat transfer from the drawing furnace 201 to the optical fiber preform, the gap between the optical fiber preform and the inner wall of the drawing furnace 201 is 5 mm to 15 mm.

It should be noted that the optical fiber body includes the core 101 of the optical fiber 2 , the inner cladding 20 , the middle cladding 30 and the outer cladding 40 .

The annealing device 202 is located downstream of the drawing furnace 201 and is used for annealing the main body of the optical fiber.

The residence time of the optical fiber body in the annealing device 202 is 0.067s-0.3s, and the temperature in the annealing device 202 is 1400°C-1700°C.

It should be pointed out that the annealing device 202 includes a plurality of holding furnaces, and the holding furnaces are arranged sequentially from top to bottom, and the temperatures of the holding furnaces are arranged in descending order from top to bottom.

The coating device 203 is located downstream of the annealing device 202 and is used for coating the annealed optical fiber main body.

The curing device 204 is located downstream of the coating device 203 and is used for curing the coated optical fiber body to form an optical fiber 2 .

The pulling mechanism 205 is located downstream of the curing device 204, and is used to increase the drawing speed and collect the optical fiber 2 onto the take-up tray.

The processing cabinet 206 is used for heat-treating the fiber collection tray filled with optical fibers.

When the treatment cabinet 206 is in use, first carry out vacuum treatment. The treatment cabinet 206 is evacuated to 0.015Mpa, and then filled with nitrogen in the treatment cabinet. The nitrogen purity is greater than or equal to 99.999%. The concentration of oxygen in the treatment cabinet is not more than 100ppm. The temperature range is 45℃～60℃.

Fig. 7 is a block diagram of a control device for optical fiber drawing tension provided by an embodiment of the present invention.

Optionally, as shown in FIG. 7 , the optical fiber preparation device provided by the embodiment of the present invention further includes an optical fiber drawing tension control device 207 and a tension meter 208 .

The optical fiber drawing tension control device 207 includes: a drawing tension acquiring module 2071, configured to acquire the current drawing tension of the annealed optical fiber body. The control module 2072 is configured to adjust the wire drawing speed of the traction mechanism 205 in a manner to reduce the difference between the current wire drawing tension and the target wire drawing tension according to the comparison between the current wire drawing tension and the target wire drawing tension.

The tensiometer 208 is provided between the annealing device 202 and the coating device 203 . The tensiometer 208 is connected to the control device 207 through a signal line. The tension meter 208 is used to detect the current drawing tension of the annealed optical fiber body, and transmit the detected current drawing tension signal of the optical fiber body to the control device 207 .

The upper computer 209 is connected with the control device 207 through a control line.

The current drawing tension of the fiber body can be calculated by the following formula:

In the formula, F is the current drawing tension of the fiber body; η _T is the viscosity, which is a function of temperature; S is the cross-sectional area of the fiber body; G _Z is the axial velocity gradient.

It can be seen that the current drawing tension of the optical fiber body is mainly related to the viscosity and axial velocity gradient, which are controlled by the furnace temperature and drawing speed. The uniformity of the cross-section of the optical fiber body will also have a certain impact on the current drawing tension of the optical fiber body. The influence of the drawing speed of the traction mechanism 205 on the current drawing tension is specifically manifested as: the drawing speed of the traction mechanism 205 increases, the viscosity increases, and the current drawing tension increases; the drawing speed of the traction mechanism 205 decreases, the viscosity decreases, and the current drawing tension increases. decrease.

The current drawing tension of the annealed optical fiber body is obtained by the tensiometer 208; the control device 207 compares and analyzes the obtained current drawing tension with the target drawing tension set by the host computer 209, and then adjusts the drawing speed of the traction mechanism 205 to reduce the current drawing tension. The difference between the drawing tension and the target drawing tension.

It should be noted that the target drawing tension set by the host computer 209 is when the drawing speed of the optical fiber is greater than 1800m/min during the optical fiber preparation process, and the cut-off wavelength of the optical fiber is between 1200nm and 1320nm, and the bending loss standard of the optical fiber meets the G.657A1 standard. The tension of the fiber body measured by the tensiometer.

Optionally, if the current drawing tension is greater than the first target drawing tension, then reduce the drawing speed of the pulling mechanism.

Specifically, firstly, the drawing speed of the drawing mechanism 205 is lowered by the control device 207 according to a change of not less than 1 m/min per second, and then the current drawing tension of the optical fiber main body is detected by the tension meter 208, and the detected current drawing tension of the optical fiber main body The drawing tension signal is transmitted to the control device 207, and finally the control device 207 compares and analyzes the obtained current drawing tension with the first target drawing tension set by the host computer, if the current drawing tension of the optical fiber body is less than or equal to the first target drawing tension, then Stop adjusting the drawing speed of the pulling mechanism 205, if the current drawing tension of the optical fiber body is still greater than the first target drawing tension, continue to adjust the drawing speed of the pulling mechanism 205 in the above manner.

If the current wire drawing tension is less than the second target wire drawing tension, then increase the wire drawing speed of the traction mechanism.

Specifically, firstly, the drawing speed of the drawing mechanism 205 is increased by the control device 207 according to a change of not less than 1 m/min per second, and then the current drawing tension of the optical fiber main body is detected by the tension meter 208, and the detected current drawing tension of the optical fiber main body The drawing tension signal is transmitted to the control device 207, and finally the control device 207 compares and analyzes the obtained current drawing tension with the second target drawing tension set by the host computer, if the current drawing tension of the optical fiber body is greater than or equal to the second target drawing tension, then Stop adjusting the drawing speed of the pulling mechanism 205, if the current drawing tension of the optical fiber body is still lower than the second target drawing tension, continue to adjust the drawing speed of the pulling mechanism 205 in the above manner.

It should be noted that when the optical fiber drawing speed is greater than 1800m/min, the cut-off wavelength of the optical fiber is between 1200nm and 1320nm, and the bending loss standard of the optical fiber meets the G.657A1 standard, the main body of the optical fiber measured by the tensiometer 208 Tension, the tension is the target drawing tension. The first target wire drawing tension is the upper limit value of the allowable fluctuation of the target wire drawing tension; the second target wire drawing tension is the lower limit value of the allowable fluctuation of the target wire drawing tension.

In an optional implementation manner, the first target wire drawing tension is the target wire drawing tension plus 1, and the second target wire drawing tension is the target wire drawing tension minus 1.

The control device 207 provided in the embodiment of the present application adjusts the drawing speed of the tractor 70 according to the comparison result between the current drawing tension and the target drawing tension, so as to reduce the difference between the current drawing tension and the target drawing tension, thereby effectively improving the optical fiber main body. The stability in the annealing device 202 avoids the distortion of the refractive index profile of the optical fiber, and then the bending resistance of the optical fiber 2 can still meet the ITU-TG.657A1 optical fiber standard when the maximum diameter of the outer coating layer is reduced to 175 μm-185 μm.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. scope.

Claims (10)

1. A method for preparing an optical fiber, comprising the steps of: Provide optical fiber preform; forming an optical fiber body by melting and drawing the optical fiber preform; annealing the fiber body; Coating the annealed optical fiber body to form an inner coating layer and an outer coating layer; curing the coated optical fiber body to form an optical fiber; Collecting the optical fiber on a fiber collection tray, and placing the fiber collection tray filled with optical fibers in a nitrogen atmosphere for heat treatment; Wherein, the optical fiber preform provided specifically includes: Prepare germanium-doped silicon dioxide powder body by axial vapor deposition method; Dehydroxylation and sintering the germanium-doped silicon dioxide powder body to make a core rod; preparing an inner cladding on the outside of the mandrel by an axial vapor deposition method; preparing a middle cladding outside the inner cladding of the optical fiber preform by chemical vapor deposition; preparing an outer cladding on the outside of the middle cladding of the optical fiber preform by chemical vapor deposition; Wherein, the relative refractive index of the core rod relative to the outer cladding is 0.35% to 0.45%; the relative refractive index of the inner cladding relative to the outer cladding is 0; the relative refractive index of the middle cladding relative to the outer cladding The relative refractive index of the layer is -0.1%~0. 2 . The method for preparing an optical fiber according to claim 1 , wherein the nitrogen purity in the nitrogen atmosphere is greater than or equal to 99.999%, and the heat treatment temperature in the nitrogen atmosphere is 45° C. to 60° C. 3 . 3 . The method for preparing an optical fiber according to claim 2 , wherein the time for heat treatment of the optical fiber on the take-up reel in the nitrogen atmosphere is 4 hours to 24 hours. 4 . 4. The preparation method of optical fiber according to claim 1, characterized in that, the material of the inner coating layer and the outer coating layer is acrylic resin; the elasticity of the cured acrylic resin used in the inner coating layer The modulus is less than or equal to 1.5Mpa, the viscosity during coating is 1500mPa·s～3000mPa·s and the elongation at break is greater than or equal to 120%, the coating temperature range is 28℃～60℃, and the coating pressure is 0.1MPa～ 2 MPa; The elastic modulus of the acrylic resin used in the outer coating layer after curing is greater than or equal to 550Mpa, the viscosity during coating is 1500mPa·s～3500mPa·s and the elongation at break is greater than or equal to 5%, and the coating temperature range is 28℃～60℃, coating pressure is 0.1MPa～2MPa. 5. The method for preparing an optical fiber according to claim 4, wherein the maximum radius of the inner coating layer is 72.5 μm to 77.5 μm, the maximum radius of the outer coating layer is 87.5 μm to 92.5 μm, and the inner coating layer The ratio of the thickness value of the coating layer to the thickness value of the outer coating layer is 1:0.67˜1:1.15. 6. A preparation device for an optical fiber, characterized in that it is used to prepare the optical fiber according to any one of claims 1-5, comprising a rod feeding mechanism, a wire drawing furnace, an annealing device, a coating device, a curing device, a pulling mechanism and processing cabinet; The rod feeding mechanism is used to send the optical fiber preform to the drawing furnace; The drawing furnace is located downstream of the rod feeding mechanism, and is used to heat and melt the preform into a glass state and draw it into a filamentous optical fiber body; The annealing device is located downstream of the drawing furnace and is used to anneal the optical fiber body; The coating device is located downstream of the annealing device, and is used for coating the annealed optical fiber body; The curing device is located downstream of the coating device, and is used to cure the coated optical fiber body to form an optical fiber; The pulling mechanism is located downstream of the curing device, and is used to collect the optical fiber onto the fiber take-up tray; The processing cabinet is used for heat-treating the fiber reel filled with optical fibers in a nitrogen atmosphere. 7. The optical fiber preparation device according to claim 6, further comprising a control device for optical fiber drawing tension; The device for controlling the drawing tension of the optical fiber includes: a drawing tension acquisition module, configured to acquire the current drawing tension of the annealed optical fiber body; The control module is used for adjusting the drawing speed of the pulling mechanism in a manner of reducing the difference between the current drawing tension and the target drawing tension according to the comparison between the current drawing tension and the target drawing tension. 8. The optical fiber preparation device according to claim 7, wherein the control module is configured to reduce the difference between the current drawing tension and the target drawing tension according to the comparison between the current drawing tension and the target drawing tension Regulate the drawing speed of described traction mechanism, specifically include: If the current drawing tension is greater than the first target drawing tension, then reduce the drawing speed of the traction mechanism; If the current drawing tension is less than the second target drawing tension, then increase the drawing speed of the pulling mechanism. 9. The optical fiber preparation device according to claim 8, wherein the first target drawing tension is the target drawing tension plus 1, and the second target drawing tension is the target drawing tension minus 1; Wherein, the target drawing tension is measured by a tensiometer when the optical fiber drawing speed is greater than 1800m/min, the cut-off wavelength of the optical fiber is between 1200nm and 1320nm, and the bending loss standard of the optical fiber meets the G.657A1 standard during the optical fiber preparation process Tension in the fiber body. 10. The optical fiber preparation device according to any one of claims 6-9, characterized in that the nitrogen purity in the nitrogen atmosphere is greater than or equal to 99.999%, and the temperature for heat treatment in the nitrogen atmosphere is 45°C ~60°C; The time for heat treatment of the optical fiber on the take-up reel in the nitrogen atmosphere is 4 hours to 24 hours.

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