Ultra-low loss optical fiber and method of making the same

Abstract

The application discloses an ultra-low-loss optical fiber, comprising the following steps: S1, depositing a core rod loose body on a target rod; the target rod comprises a hollow glass tube and a plug assembly; the lower end of the hollow glass tube is provided with a tapered portion; the inner side wall of the lower end of the tapered portion is provided with a hollow annular portion; the plug assembly comprises a plug and a plug-in column; the plug is provided with an embedded portion embedded in the middle region of the annular portion and an anti-disengagement portion abutting against the upper end surface of the annular portion; the plug is provided with a plurality of through holes penetrating the plug from top to bottom; the plug-in column is provided with a through hole penetrating the plug-in column from top to bottom; the through hole is filled with particulate matter; the particulate matter is provided with gaps; the plug-in column is inserted into the corresponding through hole to block the through hole; S2, performing a dehydration operation on the core rod loose body; S3, processing a core rod; S4, depositing an outer cladding loose body on the outer surface of the core rod; S5, processing an optical fiber preform; and S6, obtaining the optical fiber through drawing, cooling, coating, solidification and winding. The application is beneficial to the later dehydration operation and improves the passing efficiency of the dehydration atmosphere.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical fiber technology, in particular to an ultra-low-loss optical fiber and a preparation method thereof. BACKGROUND

[0002] The VAD method for preparing the optical fiber core rod loose body adopts two lamps to deposit the loose body, one lamp is connected with the raw material gas and the doping gas to deposit the core loose body, and the other lamp is connected with only the raw material gas to deposit the cladding loose body. The two lamps are arranged longitudinally, and the core loose body and the cladding loose body grow at the same time. The GeO2 doped in the core has good stability and will not diffuse to the cladding. However, the ultra-low-loss optical fiber requires less or no GeO2 in the core and F elements in the cladding to reduce the refractive index.

[0003] At present, when the VAD method is used to prepare the core rod loose body, the generated silicon oxyfluoride has poor stability, and the F elements in the cladding may diffuse into the core loose body. After sintering, the refractive index of the core is also reduced, and the refractive index difference between the core and the cladding cannot meet the requirements, thereby increasing the attenuation of the obtained optical fiber.

[0004] Therefore, in order to prevent the diffusion of the F elements in the cladding to the core during deposition, at present, a dense silica barrier layer is artificially added at the core-cladding interface by the OVD method to prevent the diffusion of the F elements into the core. Through dehydration sintering, a qualified ultra-low-attenuation optical fiber core rod is obtained. However, when the loose body enters the dehydration sintering link, the dehydration atmosphere cannot pass through the silica barrier layer because the density of the silica barrier layer is too large, resulting in insufficient dehydration atmosphere in the core loose body, and the -OH in the core loose body cannot be completely removed.

[0005] In view of the above problems, the patent document with the publication number CN107522396A discloses a preparation method of an optical fiber. A hollow glass tube is used as a target rod (a hole with a diameter of 6 mm is formed at the lower end of the target rod), and when the core loose body and the cladding loose body are deposited, the temperature at the core-cladding interface is increased by using a hydrogen-oxygen flame to make the silica at the interface shrink appropriately, so as to form a dense silica barrier layer, which can effectively prevent the diffusion of the F elements in the cladding into the core loose body, so that the refractive index difference between the core and the cladding of the optical fiber meets the requirements, thereby realizing the preparation of the ultra-low-attenuation optical fiber. The hollow glass tube is used as the target rod, and the hollow glass tube target rod is directly connected with the core loose body. When dehydration is performed subsequently, the dehydration atmosphere can not only penetrate from the outside of the cladding loose body to the inside, but also can be directly introduced into the core through the hollow glass tube. In this way, even if the dehydration atmosphere outside cannot penetrate into the core, the -OH in the core can also be completely removed, thereby achieving the reduction of the water peak.

[0006] The patent document has the following problems: because of the design of the target rod opening, more time is needed for the particles to reliably adhere to the target rod at the beginning of deposition; because of the design of the lower end of the target rod opening, more particles enter the inside of the target rod during deposition, which easily blocks the thinner part of the lower end of the target rod, and during dehydration at a lower pressure, it is difficult for the dehydration atmosphere to enter the core loose body through the lower end of the target rod.

[0007] Especially for large-size special glass rods, because of the large diameter, the above problems will cause the preparation time to be greatly prolonged. SUMMARY

[0008] The present application is directed to the above problems, overcomes at least one deficiency, and provides an ultra-low loss optical fiber and a preparation method thereof.

[0009] The technical scheme adopted by the present application is as follows:

[0010] An ultra-low loss optical fiber, comprising the following steps:

[0011] S1, depositing a core rod loose body on a target rod, the core rod loose body comprising, from inside to outside, a core layer loose body, a silica barrier layer, and an inner cladding layer loose body; the target rod comprising a hollow glass tube and a plug assembly, the lower end of the hollow glass tube having a tapered portion, the inner side wall of the tapered portion having a hollow annular portion at the lower end, the plug assembly comprising a plug and a plug column, the plug having an embedded portion embedded in the middle region of the annular portion and a anti-disengagement portion abutting against the upper end surface of the annular portion, the plug having a plurality of through holes penetrating up and down, the plug column having a through hole penetrating up and down, the through hole being filled with particles, the particles having gaps between them, the plug column being inserted into the corresponding through hole to block the through hole;

[0012] S2, after deposition, performing dehydration operation on the core rod loose body, the dehydration atmosphere entering the core layer loose body through the hollow glass tube and penetrating from the outside to the inside of the cladding layer loose body, to obtain the dehydrated core rod loose body;

[0013] S3, sequentially sintering, extending, and etching the dehydrated core rod loose body to obtain a core rod;

[0014] S4, depositing an outer cladding layer loose body on the outer surface of the core rod;

[0015] S5, performing dehydration and sintering operation on the outer cladding layer loose body to obtain an optical fiber preform;

[0016] S6, heating the optical fiber preform through a drawing furnace, the lower end of the optical fiber preform being melted to form a wire;

[0017] S7, the wire first cools and sets through a setting tube, and then further cools through a cooling tube;

[0018] S8, coating and curing the cooled optical fiber, and then winding the optical fiber.

[0019] The plug assembly is arranged in the hollow glass tube, so that the lower end of the target rod is blocked when the core rod loose body is deposited, the particles can be quickly attached, the deposition efficiency can be effectively improved, and the waste of raw materials is reduced. In addition, due to the design of the plug assembly, the lower end opening of the hollow glass tube can be arranged to be larger, thereby forming a plurality of through holes, which is beneficial to the subsequent dehydration operation and improves the passing efficiency of the dehydration atmosphere. The blocking through hole is realized by the plug column with the particulate matter, so that the deposition particles can be prevented from entering the hollow glass tube through the through hole during deposition, and the dehydration atmosphere can enter the core loose body through the particulate matter with gaps during dehydration.

[0020] In actual application, the plug column can be removed from the through hole to achieve.

[0021] In actual application, the material of the plug is glass, and the main body of the plug column can also be glass.

[0022] In one embodiment of the present application, before the dehydration operation of the core rod loose body in step S2, the step of removing the plug column from the plug is further included.

[0023] In one embodiment of the present application, the plug assembly further includes a separation plate, the separation plate has a plurality of through holes corresponding to the through holes, and the middle part of the separation plate further has a convex column;

[0024] The plug column includes a small-diameter part and a large-diameter part located at the upper end of the small-diameter part, the diameter of the large-diameter part is greater than the diameter of the through hole and the diameter of the through hole;

[0025] The separation plate is located between the large-diameter part and the upper end of the plug, and the small-diameter part of the plug column enters the through hole after passing through the through hole;

[0026] The separation plate is lifted by driving the convex column to lift, and each plug column is lifted to separate from the plug.

[0027] The design of the separation plate enables each plug column to be separated from the plug simultaneously when the separation plate is removed, so that the through hole is opened, and the dehydration atmosphere can pass through more efficiently during dehydration, thereby reducing the dehydration time.

[0028] In one embodiment of the present application, the side wall of the through hole has a positioning convex strip, the lower end of the small-diameter part of the plug column is in contact with the positioning convex strip, and when the lower end of the small-diameter part of the plug column is in contact with the positioning convex strip, the lower end of the large-diameter part of the plug column has a set distance from the separation plate;

[0029] The upper end of the convex column has a conical table structure, and the conical table structure is smaller at the top and larger at the bottom; the plug column is removed from the plug by a removal mechanism, and the removal mechanism comprises:

[0030] A pressing plate, a middle part of the pressing plate having a mounting groove, the pressing plate being used for cooperating with each large-diameter part;

[0031] An elastic assembly arranged on a side wall of the mounting groove, the elastic assembly being used for cooperating with the conical table structure;

[0032] A driving rod fixed with the pressing plate;

[0033] A driving assembly used for driving the driving rod to move along the axis direction of the hollow glass tube.

[0034] When the removal mechanism works, the pressing plate is controlled to move downward, the pressing plate is in contact with each large-diameter part, each plug column is moved downward and the convex point is pressed to break, so that the connection layer between the small-diameter part and the core loose body can be conveniently destroyed, the plug column is conveniently separated, the subsequent dehydrated atmosphere can better enter the core loose body, meanwhile, the elastic assembly is in contact with the conical table structure and is compressed to be restored, when the elastic assembly is no longer in contact with the conical table structure, the elastic assembly is restored and is located at the lower part of the conical table structure, at this time, the pressing plate is controlled to move upward, the elastic assembly drives the convex column to move upward, that is, the separation plate is driven to move upward, and finally each loose plug column is driven to move upward and separate from the plug.

[0035] In one embodiment of the present application, a side wall of the mounting groove has a mounting cavity, and the elastic assembly comprises:

[0036] A pin slidably arranged in the mounting cavity, a movement direction of the pin being perpendicular to the axis of the mounting groove;

[0037] An elastic member arranged in the mounting cavity and cooperating with the pin, used for making the pin have a tendency to move away from the mounting cavity.

[0038] In one embodiment of the present application, the elastic assembly has multiple groups and is uniformly distributed around the axis of the mounting groove, the pin has an initial working position and a compressed working position, and the elastic member is used for keeping the pin in the initial working position.

[0039] In one embodiment of the present application, the particulate matter is silicon dioxide.

[0040] In one embodiment of the present application, the density of the particulate matter in the through hole is 0.3-0.7 times the density of the core loose body.

[0041] The particulate matter in the through hole is more sparse, and the dehydrated atmosphere is conveniently passed through.

[0042] In one of the embodiments of the present application, in step S1, the deposition operation is performed by the first torch, the second torch and the third torch which are sequentially and spaced apart from bottom to top, wherein the first torch is used to form the core loose body, the second torch is used to form the silica barrier layer, and the third torch is used to form the inner cladding loose body.

[0043] The second torch is used to heat the outer side of the core loose body, so that the silica at the interface of the core loose body is appropriately shrunk to form a silica barrier layer with a larger density, which can effectively prevent the F element in the inner cladding loose body from diffusing into the core loose body, so that the refractive index difference between the core layer and the cladding layer of the optical fiber meets the requirements, thereby realizing the preparation of the ultra-low-loss optical fiber.

[0044] The present application also discloses an ultra-low-loss optical fiber prepared by the preparation method of the ultra-low-loss optical fiber.

[0045] The present application has the following beneficial effects: the plug assembly is arranged in the hollow glass tube, so that the lower end of the target rod is blocked when the core rod loose body is deposited, the particles can be quickly attached, the deposition efficiency can be effectively improved, and the waste of raw materials can be reduced; in addition, due to the design of the plug assembly, the lower end opening of the hollow glass tube can be arranged to be larger, so as to form a plurality of through holes, which is beneficial to the subsequent dehydration operation and improves the passing efficiency of the dehydration atmosphere. The blocking through hole is realized by the plug column with particles, so that the deposition particles can be prevented from entering the hollow glass tube through the through hole during deposition, and the dehydration atmosphere can enter the core loose body through the particles with gaps during dehydration. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is a sectional view of the target rod;

[0047] Figure 2 is an enlarged view of A of Figure 1

[0048] Figure 3 is a schematic view of the target rod on which the core rod loose body is deposited;

[0049] Figure 4 is a sectional view of the plug column;

[0050] Figure 5 is a schematic view of the removal mechanism moving down to approach the plug assembly;

[0051] Figure 6 is an enlarged view of B of Figure 5

[0052] Figure 7 is a schematic view of the removal mechanism moving down to approach the plug assembly;

[0053] Figure 8 is​​Figure 7 is an enlarged view of C in

[0054] Figure 9 is an enlarged view of C in Figure 8

[0055] Figure 10 is a schematic view of three torches working;

[0056] Figure 11 is a schematic view of the dehydration of the loose core;

[0057] The reference signs in the drawings refer to:

[0058] 1, loose core; 2, loose core layer; 3, silica barrier layer; 4, loose inner cladding layer; 5, hollow glass tube; 6, plug assembly; 7, plug; 8, tapered portion; 9, annular portion; 10, plug post; 11, embedded portion; 12, anti-disengagement portion; 13, through hole; 14, through hole; 15, particulate matter; 16, disengagement plate; 17, through hole; 18, protruding post; 19, large diameter portion; 20, small diameter portion; 21, positioning ridge; 22, tapered platform structure; 23, pressing plate; 24, mounting groove; 25, elastic assembly; 26, drive rod; 27, mounting cavity; 28, pin; 29, elastic member; 30, first torch; 31, second torch; 32, third torch. DETAILED DESCRIPTION

[0059] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0060] In the description of the present application, it should be noted that the positions or location relationships indicated by the terms “inner”, “outer” and the like are based on the positions or location relationships shown in the drawings, or the positions or location relationships in which the products of the present application are usually placed, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular position, be constructed and operated in a particular position, and therefore cannot be understood as a limitation on the present application. In addition, the terms “first”, “second” and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0061] ​In the description of the present application, it is also necessary to explain that, unless otherwise explicitly specified and limited, the terms "arrangement", "connection" should be understood broadly, for example, it can be fixedly connected, or detachably connected, or integrally connected, it can be directly connected, or indirectly connected through an intermediate medium, it can be the communication inside 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.

[0062] The present application will be described in detail below in combination with the accompanying drawings.

[0063] As shown in Figure 1 , 2 , 3, 4 and 11, an ultra-low-loss optical fiber comprises the following steps:

[0064] S1, a core rod loose body 1 is deposited on a target rod, the core rod loose body 1 comprises, from inside to outside, a core layer loose body 2, a silica barrier layer 3 and an inner cladding loose body 4; the target rod comprises a hollow glass tube 5 and a plug assembly 6, the lower end of the hollow glass tube 5 has a tapered portion 8, the inner side wall of the lower end of the tapered portion 8 has a hollow annular portion 9, the plug assembly 6 comprises a plug 7 and a plug column 10, the plug 7 has an embedded portion 11 embedded in the middle region of the annular portion 9 and a anti-disengagement portion 12 abutting against the upper end surface of the annular portion 9, the plug 7 has a plurality of through holes 13 penetrating up and down, the plug column 10 has a through hole 14 penetrating up and down, the through hole 14 is filled with particulate matter 15, the particulate matter 15 has a gap therebetween, and the plug column 10 is inserted into the corresponding through hole 13 to block the through hole 13;

[0065] S2, after the deposition is completed, the core rod loose body 1 is subjected to a dehydration operation, the dehydration atmosphere enters the core layer loose body 2 through the hollow glass tube 5 and penetrates from the outside to the inside of the cladding loose body, and a dehydrated core rod loose body 1 is obtained;

[0066] S3, the dehydrated core rod loose body 1 is sequentially subjected to sintering, elongation and etching to obtain a core rod;

[0067] S4, an outer cladding loose body is deposited on the outer surface of the core rod;

[0068] S5, the outer cladding loose body is subjected to a dehydration and sintering operation to obtain an optical fiber preform;

[0069] S6, the optical fiber preform is heated by a drawing furnace, and the lower end of the optical fiber preform is melted to form a wire;

[0070] S7, the wire that is hanging down is first cooled and shaped by a shaping tube, and then further cooled by a cooling tube;

[0071] S8, the cooled optical fiber is subjected to a coating and curing process operation, and then wound to obtain an optical fiber.

[0072] The plug assembly 6 is arranged in the hollow glass tube 5, so that when the core rod loose body 1 is deposited, the lower end of the target rod is blocked, which can make the particles adhere quickly and effectively improve the deposition efficiency and reduce the waste of raw materials. In addition, because of the design of the plug assembly 6, the lower end opening of the hollow glass tube 5 can be arranged larger, thereby forming a plurality of through holes 13, which is beneficial to the later dehydration operation and improves the through efficiency of the dehydration atmosphere. The blocking of the through hole 13 is realized by the plug column 10 with the particulate matter 15, so that the deposition particles can be prevented from entering the hollow glass tube 5 through the through hole 13 during deposition, and the dehydration atmosphere can enter the core loose body 2 through the particulate matter 15 with gaps during dehydration.

[0073] In actual use, in order to further increase the dehydration efficiency, the plug column 10 can be removed from the through hole 13.

[0074] In actual use, the material of the plug 7 is glass, and the main body of the plug column 10 can also be glass.

[0075] In the embodiment, before the dehydration operation of the core rod loose body 1 in step S2, the step of removing the plug column 10 from the plug 7 is further included.

[0076] As shown in Figure 2 , 5 , 6, 7, 8 and 9, in the embodiment, the plug assembly 6 further includes a separation plate 16, the separation plate 16 has a plurality of through holes 17 corresponding to the through holes 13, and the middle part of the separation plate 16 further has a protruding column 18;

[0077] The plug column 10 includes a small-diameter part 20 and a large-diameter part 19 located at the upper end of the small-diameter part 20, and the diameter of the large-diameter part 19 is greater than the diameter of the through hole 13 and the diameter of the through hole 17;

[0078] The separation plate 16 is located between the large-diameter part 19 and the upper end of the plug 7, and the small-diameter part 20 of the plug column 10 passes through the through hole 17 and enters the through hole 13;

[0079] The separation plate 16 is lifted by driving the protruding column 18 to lift, and each plug column 10 is lifted to separate from the plug 7.

[0080] The design of the separation plate 16 can simultaneously drive each plug column 10 to separate from the plug 7 when the separation plate 16 is removed, so that the through hole 13 is opened, and the dehydration atmosphere can pass through more efficiently during dehydration, thereby reducing the dehydration time.

[0081] As shown in Figure 2 , 6As shown in Figs. 7 and 8, in the present embodiment, the side wall of the through hole 13 has a positioning protrusion 21, the lower end of the small-diameter portion 20 of the plug post 10 is in contact with the positioning protrusion 21, and when the lower end of the small-diameter portion 20 of the plug post 10 is in contact with the positioning protrusion 21, the lower end face of the large-diameter portion 19 of the plug post 10 has a set distance from the disengagement plate 16;

[0082] The upper end of the protrusion 18 has a tapered platform structure 22, and the tapered platform structure 22 is smaller at the top and larger at the bottom; the plug post 10 is removed from the plug 7 by a removal mechanism, and the removal mechanism includes:

[0083] A pressing plate 23, the middle part of the pressing plate 23 has a mounting groove 24, and the pressing plate 23 is used to cooperate with each large-diameter portion 19;

[0084] An elastic assembly 25 is arranged on the side wall of the mounting groove 24, and the elastic assembly 25 is used to cooperate with the tapered platform structure 22;

[0085] A driving rod 26 is fixed with the pressing plate 23;

[0086] A driving assembly is used to drive the driving rod 26 to move along the axis direction of the hollow glass tube 5.

[0087] When the removal mechanism works, the pressing plate 23 is controlled to move downward, the pressing plate 23 is in contact with each large-diameter portion 19 to make each plug post 10 move downward and break the protrusions, so that the connection layer between the small-diameter portion 20 and the core loose body 2 can be easily damaged, which facilitates the disengagement of the plug post 10 and the better entry of the subsequent dehydration atmosphere into the core loose body 2, at the same time, the elastic assembly 25 is in contact with the tapered platform structure 22 and is compressed, and when the elastic assembly 25 is no longer in contact with the tapered platform structure 22 during the downward movement, the elastic assembly 25 is reset, and after the elastic assembly 25 is reset, it is located at the lower part of the tapered platform structure 22, at this time, the pressing plate 23 is controlled to move upward, the elastic assembly 25 drives the protrusion 18 to move upward, that is, it can drive the disengagement plate 16 to move upward, and finally drive each loosened plug post 10 to move upward and disengage from the plug 7.

[0088] In actual application, the driving assembly can be various forms of existing driving structures, including but not limited to straight push rods, rodless cylinders, conveyor belt assemblies, gear and rack assemblies, etc.

[0089] As shown in Figs. 7 and 8, in the present embodiment, the side wall of the through hole 13 has a positioning protrusion 21, the lower end of the small-diameter portion 20 of the plug post 10 is in contact with the positioning protrusion 21, and when the lower end of the small-diameter portion 20 of the plug post 10 is in contact with the positioning protrusion 21, the lower end face of the large-diameter portion 19 of the plug post 10 has a set distance from the disengagement plate 16; Figure 9

[0090] A pin 28 is slidingly arranged in the mounting cavity 27, and the movement direction of the pin 28 is perpendicular to the axis of the mounting groove 24;

[0091] An elastic element 29 is arranged in the mounting cavity 27 and cooperates with the pin 28, and is used to make the pin 28 have a tendency to move away from the side of the mounting cavity 27. ​

[0092] In this embodiment, there are multiple groups of elastic components 25, which are evenly distributed around the axis of the installation slot 24. The pin 28 has an initial working position and a compressed working position. The elastic member 29 is used to keep the pin 28 in the initial working position.

[0093] like Figure 4 As shown, in this embodiment, the particles 15 are silicon dioxide. In this embodiment, the density of the particles 15 in the through-holes 14 is 0.3 to 0.7 times the density of the core loose body 2. The particles 15 in the through-holes 14 are more sparse, which facilitates the passage of the dehydrating atmosphere.

[0094] like Figure 10 As shown, in this embodiment, in step S1, the deposition operation is performed by a first burner 30, a second burner 31 and a third burner 32 which are sequentially arranged from bottom to top, wherein the first burner 30 is used to form a core layer loose body 2, the second burner 31 is used to form a silica barrier layer 3, and the third burner 32 is used to form an inner cladding loose body 4.

[0095] The second blowtorch 31 is used to heat the outside of the core loose body 2, so that the silica at the interface of the core loose body 2 shrinks appropriately, forming a silica barrier layer 3 with a higher density, which can effectively prevent the F element in the inner cladding loose body 4 from diffusing into the core loose body, so that the refractive index difference between the core layer and the cladding of the optical fiber meets the requirements, thereby realizing the preparation of ultra-low attenuation optical fiber.

[0096] In this embodiment, the dehydration atmosphere is composed of helium and chlorine. The content of chlorine in the dehydration atmosphere is 4% to 8%, preferably 5% to 7%.

[0097] This embodiment also discloses an ultra-low loss optical fiber, which is prepared by the ultra-low loss optical fiber preparation method of this embodiment.

[0098] The above description is only a preferred embodiment of the present invention and does not limit the scope of patent protection of the present invention. Any equivalent structural transformation made by using the contents of the description and drawings of the present invention, directly or indirectly applied to other related technical fields, is also included in the scope of protection of the present invention.

Claims

1. A method of making an ultra-low-loss optical fiber, characterized in that, The method comprises the following steps: S1, depositing a core rod loose body on a target rod, the core rod loose body comprising, from inside to outside, a core layer loose body, a silica barrier layer, and an inner cladding layer loose body; the target rod comprising a hollow glass tube and a plug assembly, the lower end of the hollow glass tube having a tapered portion, the inner side wall of the lower end of the tapered portion having a hollow annular portion, the plug assembly comprising a plug and a plug-in column, the plug having an embedded portion embedded in the middle region of the annular portion and a anti-disengagement portion abutting against the upper end surface of the annular portion, the plug having a plurality of through holes penetrating up and down, the plug-in column having a through hole penetrating up and down, the through hole being filled with particulate matter, the particulate matter having gaps between them, the plug-in column being inserted into the corresponding through hole to block the through hole; S2, after the deposition is completed, performing a dehydration operation on the core rod loose body, the dehydration atmosphere entering the core layer loose body through the hollow glass tube and penetrating from the outside to the inside of the cladding layer loose body, to obtain a dehydrated core rod loose body; S3, sequentially performing sintering, elongation, and etching on the dehydrated core rod loose body to obtain a core rod; S4, depositing an outer cladding layer loose body on the outer surface of the core rod; S5, performing dehydration and sintering operations on the outer cladding layer loose body to obtain an optical fiber preform; S6, heating the optical fiber preform through a drawing furnace, the lower end of the optical fiber preform being melted to form a wire; S7, the wire first cools and shapes through a shaping tube, and then further cools through a cooling tube; S8, performing coating and curing process operations on the cooled optical fiber, and then winding to obtain an optical fiber.

2. The method of making an ultra-low loss optical fiber of claim 1, wherein, Before the dehydration operation on the core rod loose body in step S2, the method further comprises a step of removing the plug-in column from the plug.

3. The method of making an ultra-low loss optical fiber of claim 2, wherein, The plug assembly further comprises a disengagement plate having a plurality of through holes corresponding to the through holes, and the middle portion of the disengagement plate further has a protruding column; The plug-in column comprises a small-diameter portion and a large-diameter portion located at the upper end of the small-diameter portion, the diameter of the large-diameter portion being greater than the diameter of the through hole and the diameter of the through hole; The disengagement plate is located between the large-diameter portion and the upper end of the plug, and the small-diameter portion of the plug-in column enters the through hole after passing through the through hole; The disengagement plate is lifted by lifting the protruding column, and each plug-in column is lifted to disengage from the plug.

4. The method of claim 3, wherein the step of heating is performed at a temperature of 1,000°C to 1,500°C. The side wall of the through hole has a positioning protruding strip, the lower end of the small-diameter portion of the plug-in column is in contact with the positioning protruding strip, and when the lower end of the small-diameter portion of the plug-in column is in contact with the positioning protruding strip, the lower end surface of the large-diameter portion of the plug-in column has a set distance from the disengagement plate; The upper end of the protruding column has a tapered table structure, and the tapered table structure is smaller at the top and larger at the bottom; the plug-in column is removed from the plug by a removal mechanism, and the removal mechanism comprises: a pressing plate, the middle portion of the pressing plate having a mounting groove, the pressing plate being used for cooperating with each large-diameter portion; a elastic assembly arranged on the side wall of the mounting groove, the elastic assembly being used for cooperating with the tapered table structure; a driving rod fixed with the pressing plate; a driving assembly for moving the driving rod along the axis direction of the hollow glass tube; When the moving-out mechanism works, the control pressure plate moves downward, the pressure plate contacts with each large diameter part, each plug post moves downward and the convex point is pressed to break, the elastic component is compressed first, then resets and is located at the lower part of the conical table structure; the control pressure plate moves upward, the elastic component drives the convex post to move upward, the disengagement plate moves upward and each plug post moves upward to disengage the plug.

5. The method of claim 4, wherein the step of heating is performed at a temperature of 1,000°C to 1,500°C. The side wall of the mounting slot has a mounting cavity, and the elastic component comprises: a pin which is slidingly mounted in the mounting cavity and whose movement direction is perpendicular to the axis of the mounting slot; an elastic member which is located in the mounting cavity and cooperates with the pin to make the pin have a tendency to move away from the mounting cavity.

6. The method of making an ultra-low loss optical fiber of claim 5, wherein, The elastic component has multiple groups which are uniformly distributed around the axis of the mounting slot, and the pin has an initial working position and a compressed working position, and the elastic member is used to keep the pin in the initial working position.

7. The method of making an ultra-low loss optical fiber of claim 1, wherein, The particulate matter is silicon dioxide.

8. The method of making an ultra-low loss optical fiber of claim 7, wherein, The density of the particulate matter in the through hole is 0.3-0.7 times the bulk density of the core layer.

9. The method of making an ultra-low-loss optical fiber of claim 1, wherein, In step S1, a deposition operation is performed by sequentially and intervally arranging a first torch, a second torch and a third torch from bottom to top, wherein the first torch is used to form a core layer bulk, the second torch is used to form a silicon dioxide barrier layer, and the third torch is used to form an inner cladding layer bulk.

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