Layered co-extrusion die and production equipment for making polymer optical fiber

Abstract

The embodiment of the present application relates to the technical field of plastic optical fiber, and particularly relates to a layered co-extrusion die for manufacturing polymer optical fiber and a production device. In the embodiment of the present application, the die body comprises a plurality of annular components arranged in sequence and spaced apart from each other from inside to outside, and a flow channel of polymer melt is arranged between two adjacent annular components. In the plurality of annular components, a plurality of hollow columns extending along the axial direction of the annular component are further arranged between at least two adjacent annular components, and the hollow columns are distributed at intervals. In the process of preparing an optical fiber preform by using the die, the side wall of the hollow column is used to prevent the polymer melt from flowing into the inner cavity of the hollow column, so as to form the preform cavity. The die provided in the embodiment of the present application can be used to realize the industrial production of the optical fiber preform of the annular cavity polymer optical fiber by using the layered co-extrusion process, and the optical fiber preform is drawn in the subsequent process, so as to realize the industrial production of the annular cavity polymer optical fiber.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the technical field of plastic optical fiber, in particular to a layered co-extrusion die and production equipment for manufacturing polymer optical fiber. BACKGROUND

[0002] Polymer optical fiber (POF) is a new type of optical fiber using high-transmittance polymer as light guide medium, and the core diameter is generally less than one millimeter. The plastic optical fiber has excellent flexibility, anti-vibration and anti-electromagnetic interference characteristics.

[0003] Traditional optical fiber plays an important role in optical communication, but it has problems such as light loss and dispersion. In order to overcome the problems of traditional optical fiber, ring cavity optical fiber gradually develops. The ring cavity optical fiber includes photonic bandgap photonic crystal fiber (PBG-PCF) and Bragg fiber, and the cross section is composed of very small air hole array. These air holes are some capillaries with a diameter of the order of the wavelength of light, which extend in the optical fiber.

[0004] At present, the production method of ring cavity optical fiber is mainly preform drawing process, that is, drilling holes in the quartz optical fiber preform to make microstructure, and then further stretching into a wire to make the optical fiber structure size meet the requirements. But the preform drawing process is currently only suitable for the industrial production of ring cavity quartz optical fiber, and is not suitable for the industrial production of ring cavity polymer optical fiber. SUMMARY

[0005] The embodiment of the present application provides a layered co-extrusion die and production equipment for manufacturing polymer optical fiber, which can realize the industrial production of ring cavity polymer optical fiber.

[0006] In order to solve the above technical problems, the embodiment of the present application provides the following technical solutions:

[0007] In a first aspect of the present application, a layered co-extrusion die for manufacturing a polymer optical fiber is provided, the polymer optical fiber comprising a core layer and a cladding layer, the cladding layer comprising a plurality of annular stacked structures arranged in a radial direction of the polymer optical fiber, and at least two adjacent stacked structures of the plurality of stacked structures are stacked to form a plurality of spaced cavities, the die is used for manufacturing a fiber preform of the polymer optical fiber, the fiber preform comprising a preformed hollow core layer and a preformed cavity; the die comprises a die body comprising a plurality of annular components arranged in a radial direction of the die body, and a flow channel of polymer melt is arranged between two adjacent annular components; in the plurality of annular components, a plurality of hollow core columns extending in an axial direction of the annular components are arranged between at least two adjacent annular components, and each hollow core column is spaced apart; in a process of manufacturing the fiber preform by using the die, a side wall of the hollow core column is used to prevent the polymer melt from flowing into an inner cavity of the hollow core column to form the preformed cavity.

[0008] In an embodiment of the present application, the die body comprises a plurality of annular components arranged in a radial direction of the die body, and a flow channel of polymer melt is arranged between two adjacent annular components; in the plurality of annular components, a plurality of hollow core columns extending in an axial direction of the annular components are arranged between at least two adjacent annular components, and each hollow core column is spaced apart; in a process of manufacturing the fiber preform by using the die, a side wall of the hollow core column is used to prevent the polymer melt from flowing into an inner cavity of the hollow core column to form the preformed cavity. By using the die provided in the embodiment of the present application, the industrial production of the fiber preform of the annular cavity polymer optical fiber can be realized by using the layered co-extrusion process, and the subsequent drawing of the fiber preform can realize the industrial production of the annular cavity polymer optical fiber.

[0009] In some embodiments, the core layer is a hollow core layer, and the hollow core layer is empty; a side wall of an innermost annular component of the plurality of annular components is used to prevent the polymer melt from flowing into an inner cavity of the innermost annular component to form the preformed hollow core layer.

[0010] In some embodiments, the die body is provided with a fiber outlet for outputting the fiber preform, and the die further comprises a gas chamber arranged at an end of the die body away from the fiber outlet; the gas chamber is used to introduce a gas into the preformed cavity through the inner cavity of the hollow core column during a drawing process of the fiber preform; and / or the gas chamber is used to introduce a gas into the preformed hollow core layer through the inner cavity of the innermost annular component during the drawing process of the fiber preform.

[0011] In some embodiments, the mold further comprises a gas pressure adjusting device arranged in the mold body; the gas pressure adjusting device is configured to control the pressure of the first gas in the preform cavity within a preset first pressure range during the drawing process of the optical fiber preform; and / or, the gas pressure adjusting device is configured to control the pressure of the second gas in the preform hollow core layer within a preset second pressure range during the drawing process of the optical fiber preform.

[0012] In some embodiments, the gas pressure adjusting device comprises a temperature control device; the temperature control device is configured to adjust the pressure of the first gas and / or the second gas by controlling the temperature of the mold body during the drawing process of the optical fiber preform.

[0013] In some embodiments, the mold further comprises a gas pressure sensor arranged in the mold body; the gas pressure sensor is configured to monitor the pressure of the first gas in the preform cavity during the drawing process of the optical fiber preform; and / or, the gas pressure sensor is configured to monitor the pressure of the second gas in the preform hollow core layer during the drawing process of the optical fiber preform.

[0014] In some embodiments, the multi-layer stack structure comprises an Nth layer stack structure and an (N+1)th layer stack structure, where N≥1 and N is a positive integer, the (N+1)th layer stack structure comprises a ring-shaped polymer layer and a plurality of support strips, the plurality of support strips are distributed on one side of the ring-shaped polymer layer close to the Nth layer stack structure, the cavity is arranged between two adjacent support strips, and the flow channel comprises an Nth layer flow channel and an (N+1)th layer flow channel; the Nth layer flow channel is configured to form the Nth layer preform stack structure by using the Nth layer polymer melt entering the Nth layer flow channel; and the (N+1)th layer flow channel is configured to form a plurality of support strips by allowing part of the (N+1)th layer polymer melt to cover the Nth layer stack structure when the Nth layer preform stack structure moves to the feeding area of the (N+1)th layer polymer melt in the fiber drawing direction, and form an (N+1)th layer ring-shaped polymer on the side of the support strips away from the Nth layer preform stack structure by using part of the (N+1)th layer polymer melt.

[0015] In some embodiments, the optical fiber preform further comprises a preform coating layer; and the flow channel of the polymer melt further comprises a coating layer flow channel arranged outside the cladding layer flow channel, wherein the coating layer flow channel is configured to form the polymer melt of the coating layer; and when the preform cladding of the optical fiber preform moves to the feeding area of the coating layer melt, the polymer melt in the coating layer flow channel forms the preform coating layer on the outer surface of the preform cladding.

[0016] In some embodiments, the mold further comprises a plurality of metering pumps arranged on the main body, each of the metering pumps being connected to the inlet of each layer flow channel, the metering pumps being configured to control the flow rate of each layer of polymer melt into the corresponding layer flow channel; wherein the flow rate of each layer of the polymer melt is positively correlated with the cross-sectional area of the corresponding layer of the preform annular stack structure.

[0017] In a second aspect of the present application, a production device of a polymer optical fiber is provided, the production device comprising an extruder, an optical fiber drawing machine and the mold of the first aspect, the extruder, the mold and the optical fiber drawing machine being arranged in sequence; wherein the extruder is configured to melt polymer particles to form a polymer melt; the mold is configured to form an optical fiber preform using the polymer melt; and the optical fiber drawing machine is configured to perform a drawing process on the optical fiber preform, thereby obtaining the polymer optical fiber.

[0018] It should be understood that the content described in the summary section is not intended to limit the key or important features of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained according to these drawings without creative labor for those skilled in the art.

[0020] Figure 1 is a structural schematic diagram of a polymer optical fiber provided by some embodiments of the present application;

[0021] Figure 2 is a structural schematic diagram of a polymer optical fiber provided by some embodiments of the present application;

[0022] Figure 3 is a structural schematic diagram of a polymer optical fiber provided by some embodiments of the present application;

[0023] Figure 4 is a distribution schematic diagram of a layer stack structure of a polymer optical fiber provided by some embodiments of the present application;

[0024] Figure 5 is a refractive index distribution of a polymer optical fiber provided by some embodiments of the present application;

[0025] Figure 6 is a structural schematic diagram of a layered co-extrusion mold from one perspective provided by some embodiments of the present application;

[0026] Figure 7is a structure and layered co-extrusion principle schematic diagram of a layered co-extrusion die provided by some embodiments of the present application;

[0027] Figure 8 is a structure schematic diagram of a layered co-extrusion die provided by some embodiments of the present application;

[0028] Figure 9 is a structure schematic diagram of a polymer optical fiber production device provided by some embodiments of the present application;

[0029] Figure 10 is a flowchart of a polymer optical fiber preparation method provided by some embodiments of the present application;

[0030] Figure 11 is a structure and layered co-extrusion principle schematic diagram of a layered co-extrusion die provided by some embodiments of the present application;

[0031] Figure 12 is an in-feed sequence diagram of each layer of polymer melt provided by some embodiments of the present application. DETAILED DESCRIPTION

[0032] In order to make the objects, technical solutions and advantages of the present application clearer, the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0033] It should be noted that each feature of the embodiments of the present application can be combined with each other without conflict, and all within the protection scope of the present application. In addition, although the functional modules are divided in the device schematic diagram, and the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than the module division in the device schematic diagram or the order in the flowchart.

[0034] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application. The term "and / or" used in the present application includes any and all combinations of one or more related listed items.

[0035] A polymer optical fiber (POF), also known as a plastic optical fiber or a high polymer optical fiber, is made of a high molecular polymer material (such as polymethyl methacrylate), and the core diameter is generally less than one millimeter. The plastic optical fiber uses a high-transmittance polymer as a light guide medium, and has excellent flexibility, anti-vibration and anti-electromagnetic interference characteristics.

[0036] At present, the widely used plastic optical fiber on the market is step refractive index plastic optical fiber (SI-POF), and its low-loss working wavelength window is 520 nm and 650 nm. At 650 nm working wavelength, the theoretical loss limit of SI-POF is about 100 dB / km. But in actual production, the loss of plastic optical fiber products used for communication is as high as 140 dB / km-200 dB / km, and the loss in the near-infrared region is even larger. Therefore, the plastic optical fiber with polymethyl methacrylate (PMMA) as the core layer material is mainly used in short-distance communication scenarios. In addition, SI-POF is a multimode optical fiber, and its nonlinear effect will affect the transmission bandwidth. Subsequently, Japanese enterprises launched deuterated plastic optical fiber, which greatly reduced the attenuation of SI-POF, but the spectral width of deuterated plastic optical fiber is relatively narrow, the application is limited, and the cost of raw materials is too high, which is not conducive to the market promotion of products.

[0037] In order to reduce the optical loss of plastic optical fiber and improve the communication bandwidth, Japanese university research institutes and enterprises have successively launched perfluorinated plastic optical fiber and partially fluorinated plastic optical fiber, so that the refractive index of the plastic optical fiber is gradually distributed (GI-POF). However, due to the high cost of raw materials, complicated and difficult production process, the production cost is too high, which makes it difficult to enter the market and be widely applied.

[0038] Photonic bandgap photonic crystal fiber (PBG-PCF), also known as microstructure optical fiber. The cross section of PBG-PCF has a relatively complex refractive index distribution, usually containing air holes (also known as cavities) of different arrangement forms, the size of these air holes is roughly the same order of magnitude as the wavelength of light and penetrates the entire length of the device. Light waves can be confined to the fiber core area in the refractive index defect zone. PBG-PCF includes a structure with periodically varying refractive index, thereby generating a photonic band, and photons with frequencies in the forbidden band range of the photonic band are prohibited from propagating in the cladding structure. Breaking the introduced periodic structure forms a defect, which forms a defect zone with a certain frequency width, so that light waves of a specific frequency can propagate in the defect zone, that is, the light waves are radially bound to the defect area. The light guiding mechanism of photonic bandgap photonic crystal fiber is different from the principle of total internal reflection conduction light in traditional optical fiber, and it is through photonic bandgap light guiding.

[0039] Bragg fiber is a special fiber which is composed of concentric circular rings of multilayer media with periodic distribution of radial refractive index. By Bragg reflection principle, the light is bound in the defect state, i.e. the central hollow core region for transmission. The core layer of Bragg fiber is usually a hollow core structure, or a high refractive index core can be used, and the radial refractive index of the cladding is periodically distributed, which can be approximately regarded as a one-dimensional photonic bandgap photonic crystal fiber. By Bragg reflection principle, the light of specific frequency is limited in the hollow core region for transmission, which greatly reduces the material absorption loss. At the same time, since the Bragg reflection principle needs to satisfy nλ = 2dsinθ, only the light wave of specific mode can be transmitted in the core layer, therefore, the Bragg fiber can reduce the nonlinear effect of the material and improve the communication bandwidth.

[0040] The plastic optical fiber selects air as a low refractive index material in order to avoid the trouble of finding two materials with large refractive index difference, good optical performance, and similar and compatible properties in terms of thermal and mechanical properties and manufacturing process. The hollow core layer is an air layer or other low refractive index gas layer, which can not only avoid the inherent absorption loss of other materials, but also reduce the nonlinear effect, thereby reducing the optical attenuation and improving the transmission bandwidth. The introduction of Bragg stack structure enables the light to be radially bound in the hollow core layer, preventing leakage and reducing loss. By designing different sizes of Bragg stack structure, optical fibers with different working wavelength windows can be obtained, which are particularly advantageous in the field of visible light to infrared light transmission. The cladding of this kind of fiber is a stack structure with periodically varying refractive index, which can bind the light of specific frequency and specific mode in the central refractive index defect layer, i.e. the hollow core layer, according to the photonic bandgap theory and Bragg reflection principle.

[0041] The polymer optical fiber of the embodiments of the present application is also called a ring cavity polymer optical fiber. The polymer optical fiber includes a cladding structure with periodic refractive index distribution, which is formed by a plurality of ring cavities and polymer rings stacked in sequence to form a periodic refractive index distribution. The core layer of the optical fiber is a hollow core layer, and the core is formed by a gas defect such as air. In the embodiments of the present application, the stack structure with periodic refractive index distribution is introduced into the polymer optical fiber to form a photonic bandgap polymer optical fiber or a Bragg polymer optical fiber. Compared with the traditional plastic optical fiber, the polymer optical fiber has the advantages of low attenuation, high bandwidth, and transmission light frequency bandwidth, and can play a greater advantage in short distance communication of various local area networks (such as automobiles, large vehicles, military equipment, residential and office networks), and can greatly promote the process of realizing all-optical network in communication system.

[0042] The polymer optical fiber of the embodiments of the present application is also called a ring cavity polymer optical fiber, specifically, a bandgap photonic crystal fiber or a Bragg fiber. Exemplarily, Figure 1 A cross-sectional view of the ring cavity polymer optical fiber 100 is shown. As Figure 1As shown, the annular-cavity polymer optical fiber 100 includes a core layer 110 and a cladding layer 120 arranged in sequence from inside to outside along the radial direction of the annular-cavity polymer optical fiber 100. The core layer 110 can be a solid core layer or a hollow core layer. The embodiments of the present application take the core layer 110 as a hollow core layer for example.

[0043] Specifically, the core layer 110 is set as a hollow core layer to enable the light to propagate in a low-loss medium. This not only saves the trouble of finding two materials with a large difference in refractive index and good optical performance, similar and compatible in thermal and mechanical properties and manufacturing process, but also enables the product to achieve high bandwidth, low attenuation and low delay. The hollow core layer adopts a hollow structure. Generally, the hollow core layer 110 can be filled with air as a low-refractive material. In other embodiments, the hollow core layer can also be filled with other low-loss gases to minimize the material absorption loss of the light propagating in the optical fiber.

[0044] To ensure that the light is radially confined in the hollow core layer, i.e., to reduce the radial leakage of the light, the cladding layer 120 includes a plurality of layers of cavities arranged in sequence from inside to outside along the radial direction of the annular-cavity polymer optical fiber 100, and a plurality of cavities 121 in each layer of cavities are arranged in a ring around the axis of the annular-cavity polymer optical fiber 100. The cavities 121 can be filled with air as a low-refractive material, and the cavities 121 can also be filled with other low-loss gases to minimize the material absorption loss of the light propagating in the optical fiber.

[0045] Optionally, in some embodiments, to increase the flexibility of the annular-cavity polymer optical fiber 100, the annular-cavity polymer optical fiber 100 further includes a coating layer 130, and the hollow core layer 110, the cladding layer 120 and the coating layer 130 are arranged in sequence from inside to outside along the radial direction of the annular-cavity polymer optical fiber 100. Those skilled in the art can select whether to set the coating layer according to actual needs. The coating layer is a high-toughness polymer for increasing the flexibility of the optical fiber.

[0046] Figure 2 and Figure 3 Exemplary cross-sectional views of the annular-cavity polymer optical fiber of some other embodiments are shown. As shown in FIGS. 2A and 2B, Figure 2 and Figure 3 As shown, the cross-sectional shape of the cavities 121 can be any suitable shape such as a polygon or a circle. A plurality of cavities 121 in each layer of cavities are arranged in a polygon or any suitable shape such as a circle around the axis of the annular-cavity polymer optical fiber 100.

[0047] In some embodiments, the hollow core layer of the annular cavity polymer optical fiber belongs to a hollow structure, and the cladding layer has a large number of cavity structures. If a traditional extrusion process is used, the stress of the material during extrusion drawing will affect the size of the cavity and destroy the Bragg reflection condition; in addition, if one-time feeding is selected, due to the too small gap between the axial hollow columns in the mold, the feeding cannot fill the extrusion mold, resulting in irregular bubbles in the polymer optical fiber, which greatly affects the light guiding performance of the polymer optical fiber.

[0048] At present, the photonic bandgap photonic crystal optical fiber which is relatively mature in research is mostly quartz optical fiber. Holes are drilled in the quartz optical fiber preform to make microstructures, and then the preform is further drawn into a fiber to make the fiber structure size meet the requirements. At present, the production method of photonic bandgap polymer optical fiber or Bragg polymer optical fiber based on the preform drawing process is only in the experimental stage of trial production, which is far from meeting the requirements of industrialization. The production method of the classical photonic bandgap photonic crystal fiber or Bragg fiber is to stack many prepared air tubes together and then draw them; or, to drill many micro-holes on a certain length of fiber material and then draw them. These methods are not suitable for the industrial production of annular cavity polymer optical fiber.

[0049] In order to realize the industrial production of annular cavity polymer optical fiber, the cladding layer of the annular cavity polymer optical fiber is divided into a multi-layer annular stacking structure in the embodiments of the present application, so that the industrial production of annular cavity polymer optical fiber can be realized by using a layered co-extrusion process. At least two adjacent stacking structures in the multi-layer stacking structure are stacked to form a plurality of spaced cavities.

[0050] Specifically, in some embodiments, the multi-layer stacking structure includes an Nth layer stacking structure and an (N+1)th layer stacking structure, where N≥1 and N is a positive integer, the (N+1)th layer stacking structure includes a ring-shaped polymer layer and a plurality of support strips, the plurality of support strips are distributed on one side of the ring-shaped polymer layer close to the Nth layer stacking structure, and a cavity is arranged between two adjacent support strips. The support strips are used to improve the structural stability and mechanical properties of the annular cavity polymer optical fiber and increase the size of the cavity along the radial direction of the annular cavity polymer optical fiber.

[0051] Exemplarily, Figure 4 Exemplarily, Figure 1 The layers of the annular cavity polymer optical fiber (or optical fiber preform) are shown in FIG. 1. As shown in FIG. 1, Figure 4As shown, the polymer optical fiber comprises a five-layer stacked structure arranged sequentially from the inside out. The first stacked structure 410 is a ring-shaped polymer, and each of the second to fourth stacked structures includes a ring-shaped polymer layer and several support strips. For example, the fourth stacked structure 420 includes several support strips 421 and a ring-shaped polymer 422; wherein two adjacent support strips 421 and ring-shaped polymer 422, together with the ring-shaped polymer in the third stacked structure, form a cavity 440. The coating layer 430 is a ring-shaped polymer. In other embodiments, the stacked structures can be divided in other ways, for example, the innermost stacked structure (e.g., ... Figure 4 The first layer of the stacked structure (in the middle) includes a ring polymer and support strips, and the outermost layer of the stacked structure (e.g., Figure 4 The fifth layer of the stacked structure is a cyclic polymer. Figure 4 In the middle, each layer of cyclic polymer is a hollow ring arranged in concentric circles.

[0052] This is about the book. Figure 4 The relevant parameters of the annular cavity polymer optical fiber are described as follows: Inner diameter of the hollow core layer D1, outer diameter of the optical fiber D2, and polymer coating thickness h; refractive index of the polymer material n1, refractive index of the hollow core layer n2, and refractive index of the polymer coating layer n3; thickness of each polymer layer d1, distance between two adjacent annular polymer layers d2, thickness of one period of the stacked structure Λ = d1 + d2, and number of stacked structure layers η; in each stacked structure, the thickness of the support strip structure is d3, and the number is W. Specifically, in some embodiments, the outer diameter D2 of the optical fiber preform (excluding the coating thickness) ranges from 55-65 mm, such as 55 mm, 60 mm, or 65 mm, etc.; the inner diameter D1 of the hollow core layer of the optical fiber preform ranges from 15-25 mm, such as 15 mm, 20 mm, or 25 mm, etc.; and the coating thickness h of the optical fiber preform ranges from 1-3 mm, such as 1 mm, 2 mm, or 3 mm, etc. The distance d2 between two adjacent annular polymer layers in the optical fiber preform ranges from 0.3mm to 5mm, for example, 0.3mm, 1mm, 2mm, 3mm, 4mm or 5mm, etc.; the thickness of the annular polymer is 0.036-2.4mm, for example, 0.036mm, 0.03mm, 0.1mm, 1mm, 2mm or 2.4mm, etc.

[0053] Figure 5 Polymer optical fibers (e.g., provided in some embodiments of this application) are examples of polymer optical fibers. Figure 4 The refractive index distribution of polymer optical fibers (such as those in polymer optical fibers). Figure 5 As shown, the refractive index of the polymer optical fiber cladding exhibits a periodic variation. Figure 5 In the given information, n1 > n3 > n2.

[0054] To realize the industrialized production of polymer optical fiber, the application provides a layered co-extrusion die for manufacturing a fiber preform of a polymer optical fiber, for example, a fiber preform of a hollow-cavity polymer optical fiber in Figures 1 to 3 . The fiber preform comprises a preformed cavity. The layered co-extrusion die specifically comprises a die body, and the die body comprises a plurality of annular components arranged in sequence from inside to outside, and a flow channel of polymer melt is arranged between two adjacent annular components; among the plurality of annular components, a plurality of hollow columns extending along the axial direction of the annular component are further arranged between at least two adjacent annular components, and each hollow column is distributed in a spaced manner; in the process of manufacturing the fiber preform by using the die, the side wall of the hollow column is used to prevent the polymer melt from flowing into the inner cavity of the hollow column to form the preformed cavity. In the embodiment, a plurality of hollow columns extending along the axial direction of the annular component are arranged in the flow channel of at least one polymer melt, and in the process of layered co-extrusion of the polymer melt, the polymer melt in the flow channel cannot enter the inner cavity of the hollow column to form the preformed cavity.

[0055] In some embodiments, when the core layer is a hollow core layer, the hollow core layer is empty; the side wall of the innermost annular component among the plurality of annular components is used to prevent the polymer melt from flowing into the inner cavity of the innermost annular component to form a preformed hollow core layer. In other embodiments, when the core layer is a solid core layer, the inner cavity of the innermost annular component is a flow channel of the core layer polymer melt.

[0056] Figure 6 An exemplary structure schematic diagram of a perspective view of a die body is shown, which can be used to manufacture a fiber preform of a polymer optical fiber in Figure 4 , as shown in Figure 6 , the die body 600 comprises a plurality of annular components arranged in sequence from inside to outside, and the plurality of annular components can specifically be cylindrical structures distributed in a spaced manner along the same axis. The plurality of annular components comprises a first annular component 610, a second annular component 620 and a third annular component 630 arranged in sequence from inside to outside; wherein the gap between the first annular component 610 and the second annular component 620 is used to form a first preformed layer stack structure (for example Figure 4The first annular member 610 of the first flow channel of the first layer preform structure 410 corresponds to the side wall of the first flow channel of the first layer preform structure) to prevent the polymer melt in the first flow channel from entering the inner cavity of the first annular member 610 to form a preform hollow core. The second annular member 620 and the third annular member 630 are provided with a plurality of hollow core columns 640 extending along the axial direction of the annular member, and each hollow core column 640 is annularly spaced around the axis of the annular member. In some embodiments, each hollow core column 640 can be fixed to the side wall of the second annular member 620 near the third annular member 630. The cross-sectional shape of the hollow core column 640 can be any suitable shape such as polygonal, circular, or elliptical. The outer side wall of the second annular member 620, the outer side wall of the hollow core column 640, and the inner side wall of the third annular member 620 enclose the second flow channel of the second layer preform structure. The outer side wall of the hollow core column 640 prevents the polymer melt in the second flow channel from entering the inner cavity of the hollow core column 640 to form a preform hollow core.

[0057] The cladding of the photonic bandgap photonic crystal fiber includes air holes arranged in strict rules, and the air holes can be filled with air or other media. The arrangement and size of the air holes in the PBG-PCF cladding must strictly meet the required conditions to form a photonic bandgap. In some embodiments, the shape, size, spacing, arrangement, and filling of different media in the hollow core column 640 can be used to design photonic bandgap photonic crystal fibers with different characteristics.

[0058] Specifically, the flow channel of the layered co-extrusion die includes a cladding flow channel, which represents a flow channel for passing a cladding polymer melt. The cladding flow channel includes an Nth flow channel and an (N+1)th flow channel; wherein the Nth flow channel is used to form an Nth layer preform structure using the Nth layer polymer melt entering the Nth flow channel; and the (N+1)th flow channel is used to form a plurality of support strips on the Nth layer preform structure by covering part of the (N+1)th layer polymer melt on the Nth layer preform structure when the Nth layer preform structure moves to the feeding area of the (N+1)th layer polymer melt in the out-fiber direction, and part of the (N+1)th layer polymer melt forms an (N+1)th annular polymer on the side of the support strips away from the Nth layer preform structure.

[0059] In some embodiments, when the polymer optical fiber includes a coating layer, the optical fiber preform also includes a preform coating layer accordingly. Please refer to Figure 7 , the flow channel of the polymer melt further includes a coating layer flow channel 650 arranged outside the cladding flow channel, wherein the coating layer flow channel represents a flow channel for passing a coating layer polymer melt; and when the preform cladding of the optical fiber preform moves to the feeding area of the coating layer melt, the polymer melt in the coating layer flow channel forms a preform coating layer on the outer surface of the preform cladding.

[0060] Please refer to Figure 8In some embodiments, the mold body 810 is provided with a fiber outlet 811 for outputting the optical fiber preform, and the mold 800 further comprises a gas chamber 820 arranged at an end of the mold body 810 away from the fiber outlet 811; the gas chamber 820 is configured to: during the drawing process of the optical fiber preform, introduce a gas such as air into the preform cavity through the inner cavity of the hollow column; and / or, the gas chamber 820 is configured to: during the drawing process of the optical fiber preform, introduce a gas such as air into the preform hollow core layer through the inner cavity of the innermost annular component.

[0061] After the optical fiber leaves the mold, it is drawn into a fiber product that meets the specifications. During the drawing process, the radial stress of the material may extrude the cavity due to the lack of support from the hollow column. To prevent the material stress from extruding the cavity during fiber drawing and deforming it, a gas chamber is designed at the front end of the feeding mold. The gas in the gas chamber enters the axial hollow column through the pressure difference, providing internal pressure for the cavity in the final drawing link, supporting the cavity structure and preventing the radial stress of the material from extruding the cavity during drawing.

[0062] In some embodiments, the mold 800 further comprises a gas pressure adjusting device 830 arranged in the mold body; the gas pressure adjusting device 830 is configured to: during the drawing process of the optical fiber preform, control the pressure of the first gas in the preform cavity within a preset first pressure range; and / or, the gas pressure adjusting device 830 is configured to: during the drawing process of the optical fiber preform, control the pressure of the second gas in the preform hollow core layer within a preset second pressure range.

[0063] In some embodiments, the gas pressure adjusting device 830 comprises a temperature control device 831; the temperature control device 831 is configured to: during the drawing process of the optical fiber preform, adjust the pressure of the first gas and / or the second gas by controlling the temperature of the mold body 810.

[0064] In some embodiments, the air pressure adjusting device 830 further comprises an air pressure sensor 832 arranged on the mold body. The air pressure sensor 832 is configured to monitor the pressure of the first gas in the preform cavities during the drawing process of the optical fiber preform; and / or the air pressure sensor 832 is configured to monitor the pressure of the second gas in the preform hollow core layer during the drawing process of the optical fiber preform. For example, in some embodiments, the air pressure sensor 832 comprises one or more first air pressure sensors configured to monitor the pressure of the first gas in each preform cavity; specifically, the pressure of the first gas in all preform cavities can be monitored by one air pressure sensor at the same time, or the pressure of the first gas in each preform cavity can be monitored by multiple air pressure sensors respectively. In other embodiments, the air pressure sensor 832 further comprises a second air pressure sensor configured to monitor the pressure of the second gas in the preform hollow core layer.

[0065] During the drawing process, the radial stress of the optical fiber material may, without the support of the axial hollow column in the mold, cause the cavity to be extruded, and thus the cavity needs to be provided with a structure for supporting the cavity by internal pressure. An air chamber with controllable air pressure is arranged at the front end of the extrusion mold, and the air pressure is controlled by adjusting the mold temperature, changing the temperature of the air chamber, or using other methods. The pressure difference causes the air chamber gas to flow into the optical fiber cavity from the axial hollow column, providing a certain internal pressure at the end of the drawing process, offsetting the radial stress of the material caused by the drawing, and ensuring that the size and structure of the cavity do not change.

[0066] Specifically, the mold body is further provided with a plurality of material inlets, each material inlet being in communication with a corresponding flow channel, and the material inlet being configured to input polymer melt into the corresponding flow channel; the plurality of flow channels are arranged from inside to outside, and the material inlet of the outer flow channel is closer to the fiber outlet of the mold body than the material inlet of the inner flow channel.

[0067] In some embodiments, the flow channel of the polymer melt comprises a cladding flow channel and a coating flow channel arranged outside the cladding flow channel, wherein the cladding flow channel is configured to pass through the cladding polymer melt, and the coating flow channel is configured to pass through the coating polymer melt; the material inlet of the coating flow channel is closer to the fiber outlet of the mold than the material inlet of the cladding flow channel.

[0068] In some embodiments, the mold further comprises a plurality of metering pumps 840 arranged on the main body, each metering pump 840 being connected to the inlet of each layer flow channel, and the metering pump 840 is used to control the flow rate of each layer of polymer melt into each layer flow channel; wherein the flow rate of each layer of polymer melt is positively correlated with the cross-sectional area of the corresponding layer of the annular stack structure. By controlling the flow rate of each layer of polymer melt through the metering pump 840, a smaller volume of melt is injected into each layer, so that the temperature of the melt in the mold is kept uniform, and at the same time, the polymer melt can fill the gap between the axial hollow columns, reducing the material stress generated during the flow of the melt, and avoiding the influence of the stress of the flowing melt on the size of the cavity structure.

[0069] In the embodiments of the present application, the metering pump controls the flow rate of each layer of polymer melt within a predetermined flow rate range. The flow rate is also referred to as the feeding speed; if the flow rate is too low, the amount of material fed is too small, and air bubbles are easily generated during the advancement of the melt or the thickness of the stack structure is reduced; if the feeding speed is too high, the amount of material fed is too large, which is easy to cause overflow, and even extrude the cavity structure.

[0070] The embodiments of the present application also provide a production device for a polymer optical fiber. Exemplarily, Figure 9 The structural schematic diagram of the production device 90 is shown in Figure 9 As shown in the figure, the production device 90 comprises an extruder 91, an optical fiber drawing machine 93 and the mold 92 provided in the above embodiments, for example, the mold 600 in Figure 6 or Figure 7 , wherein the extruder 91, the mold 92 and the optical fiber drawing machine 93 are arranged in sequence. The extruder 91 is used to melt the polymer particles to form a polymer melt and output the polymer melt to the mold 92; the mold 92 is used to form an optical fiber preform by using the polymer melt; and the optical fiber drawing machine 93 is used to perform a drawing process on the optical fiber preform, so as to obtain a polymer optical fiber with a suitable size.

[0071] The embodiments of the present application also provide a preparation method of a polymer optical fiber, which is used to prepare the annular cavity polymer optical fiber provided in the above embodiments, for example, the annular cavity polymer optical fiber in Figures 1-3 . The preparation method of the polymer optical fiber provided in the embodiments of the present application is used to ensure that the feeding of the optical fiber is sufficient, and air bubbles are not generated during the extrusion and drawing process; to make the size of each layer of the stack structure controllable and monitorable; and to ensure that the cavity structure in each layer of the stack structure is less affected by the material stress, and at the same time, the variable air pressure is used to protect the size of the cavity structure.

[0072] Specifically, please refer to Figure 10 The method comprises the following steps:

[0073] Step 11: extruding each layer of the multi-layer stack structure corresponding to the preform stack structure of the stack structure by a layering co-extrusion process, so as to obtain an optical fiber preform with a preformed cavity;

[0074] The step 11 specifically comprises the following steps:

[0075] Step 110: extruding each layer of the multi-layer stack structure corresponding to the preform stack structure of the stack structure by a layering co-extrusion process in the order from inside to outside.

[0076] In the embodiment of the present application, when the Nth layer of polymer melt enters the Nth layer flow channel of the layering co-extrusion die, the Nth layer of preform stack structure is formed; when the Nth layer of preform stack structure runs to the feeding area of the (N+1)th layer of polymer melt in the fiber drawing direction, under the action of the layering co-extrusion die, part of the (N+1)th layer of polymer melt covers the Nth layer of stack structure to form a plurality of support strips, and part of the (N+1)th layer of polymer forms a (N+1)th layer of annular polymer on the side of the support strip away from the Nth layer of preform stack structure; wherein the feeding area of the (N+1)th layer of polymer melt is located at the front end of the fiber drawing direction relative to the feeding area of the Nth layer of polymer melt.

[0077] In some embodiments, the above method further comprises the following steps:

[0078] Step 111: during the layering co-extrusion process, the flow rate of each layer of polymer melt entering the flow channel of the layering co-extrusion die is controlled by a metering pump; wherein the flow rate of each layer of polymer melt is positively correlated with the cross-sectional area of the corresponding layer of annular stack structure.

[0079] In the embodiment, the metering pump can control the feeding amount of each layer of polymer melt, so that a smaller volume of melt is injected in each layer, so that the temperature of the melt in the die is kept consistent, and at the same time, it is beneficial for the polymer melt to fill the gap between the axial hollow columns, reduce the material stress generated during the flow of the melt, and avoid the influence of the stress of the flowing melt on the cavity structure size. The metering pump controls the feeding flow rate of each layer of polymer melt within a predetermined flow rate range. The feeding flow rate is also called the feeding speed; if the feeding flow rate is too low, the feeding amount is too small, and bubbles are easily generated during the advancement of the melt or the thickness of the stack structure is reduced; if the feeding speed is too high, the feeding amount is too large, which is easy to cause overflow, and even extrude the cavity structure.

[0080] In some embodiments, the optical fiber preform further comprises a coating layer arranged on the side of the cladding away from the hollow core layer; the above method further comprises the following steps:

[0081] Step 112: when the cladding runs along the fiber drawing direction to the feeding area of the coating layer polymer melt, the coating layer polymer melt coats the cladding on the side surface of the cladding away from the core layer; wherein the feeding area of the coating layer polymer melt is located at the front end of the fiber drawing direction relative to the feeding area of the cladding.

[0082] Step 12: performing a fiber drawing process on the optical fiber preform to make the preform cavity correspond to the cavity of the polymer optical fiber, so as to obtain the polymer optical fiber.

[0083] When the core layer is a hollow core layer, the hollow core layer is empty, and the optical fiber preform further has a preform hollow core layer, and the above step 12 specifically includes the following steps:

[0084] Step 120: performing a fiber drawing process on the optical fiber preform to make the preform cavity and the preform hollow core layer correspond to the cavity and the hollow core layer of the polymer optical fiber, respectively, so as to obtain the polymer optical fiber.

[0085] In some embodiments, the above step 12 specifically includes: inputting a first gas into the preform cavity and controlling a first gas pressure of the first gas to be within a first preset gas pressure range during the fiber drawing process on the optical fiber preform. In other embodiments, a second gas is input into the hollow core layer of the optical fiber preform and a second gas pressure of the second gas is controlled to be within a second preset gas pressure range during the fiber drawing process on the optical fiber preform. The types of the first gas and the second gas can be the same or different, and a person skilled in the art can set them according to actual needs.

[0086] Specifically, in some embodiments, a first gas is input into the preform cavity and the first gas pressure is adjusted by adjusting the temperature of the first gas to make the first gas pressure within the first preset gas pressure range during the fiber drawing process on the optical fiber preform. In other embodiments, a second gas is input into the hollow core layer of the optical fiber preform and the second gas pressure is adjusted by adjusting the temperature of the second gas to make the second gas pressure within the second preset gas pressure range during the fiber drawing process on the optical fiber preform. The first gas pressure and the second gas pressure can be the same or different, and the gas pressures in different preform cavities can be the same or different, and a person skilled in the art can set them according to actual needs.

[0087] Specifically, in some embodiments, the temperature of the first gas is adjusted by adjusting the temperature of the layered co-extrusion die to control the first gas pressure within the first preset pressure range; and / or, the temperature of the second gas is adjusted by adjusting the temperature of the layered co-extrusion die to control the second gas pressure within the second preset pressure range.

[0088] During fiber drawing: Without the support of an axial hollow column in the die, radial stress in the fiber material can compress the cavity. Therefore, a structure providing internal pressure support is needed. A pressure-controlled gas chamber is placed at the front end of the extrusion die. By adjusting the die temperature, the chamber temperature is changed, controlling the gas pressure (other methods can also be used). The pressure difference allows gas to be injected from the axial hollow column into the fiber cavity, providing a certain internal pressure during end-drawing to counteract the radial stress caused by drawing and ensure that the cavity's dimensions and structure remain unchanged.

[0089] Figure 11 An exemplary diagram illustrating the structure and layered co-extrusion principle of the mold body from another perspective is provided. Figure 11 As shown, the cladding feed inlets include a first feed inlet 710, a second feed inlet 720, a third feed inlet 730, a fourth feed inlet 740, a fifth feed inlet 750, and a sixth feed inlet 760 arranged sequentially along the fiber exit direction. The first to fifth feed inlets are for the cladding polymer melt, and the sixth feed inlet is for the coating layer polymer melt. The types of polymers entering each cladding polymer melt inlet can be the same or different. The first to sixth feed inlets 710 are connected to the first layer flow channel 711, the second layer flow channel 712, the third layer flow channel 713, the fourth layer flow channel 714, the fifth layer flow channel 715, and the sixth layer flow channel 716, respectively. The polymer melts of each layer are sequentially fed into the flow channels from the first feed inlet 710 to the sixth feed inlet 760. The feed flow rate of each flow channel is strictly controllable.

[0090] In some embodiments, the same first polymer material is input into the first to fifth inlets; a second polymer material is input into the sixth inlet, and the first and second polymer materials are of different types. The second polymer material is a high-toughness polymer material, such as a polyester polymer. The end of the mold body furthest from the fiber outlet is a pressure-controlled air chamber. By adjusting the local temperature of the end of the mold body near the air chamber, the temperature within the air chamber can be changed, resulting in different air pressures within the chamber. This pressure difference is used to guide the gas along the axial hollow column into the optical fiber (as shown by the arrow in the figure), protecting the cavity structure. Finally, the fiber outlet direction represents the direction in which the optical fiber is drawn after being extruded from the mold.

[0091] In other embodiments, the gas pressure can also be controlled in other ways, for example, by controlling the flow rate of gas into the innermost annular component cavity 780 and the hollow column cavity 770.

[0092] like Figure 12As shown, after each layer of raw material enters the extrusion die, it will continue to advance in the die and adhere to the next layer of material to form a structure of this layer of polymer ring-cavity-the next layer of polymer ring until all the stacked structures and coating layers are adhered layer by layer in the die and extruded from the die. Among them, the first to fifth layers of material are polymer materials, and the sixth layer of material is a coating layer material, and a high-toughness polymer material is selected as needed.

[0093] In the embodiments of the present application, the layered co-extrusion technology is adopted to produce the annular cavity polymer optical fiber, which eliminates the cumbersome steps of making a preform rod, and the design of the stacked structure of each layer is more controllable. The layered co-extrusion technology divides each layer of stacked structure into layers of material, which reduces the material internal stress during melt flow, avoids the generation of irregular bubbles or deformation of the extruded cavity structure due to extrusion traction. A temperature-controllable air chamber is introduced at the front end of the extrusion die, the air pressure is adjusted by controlling the temperature of the air chamber, the gas is continuously input into the axially extending hollow column by utilizing the pressure difference, the internal pressure supports the cavity structure, offsets the material internal stress generated by the melt raw material during traction flow, extrudes the cavity, and causes the size to change. The material flow of each layer is controlled by a metering pump to ensure that each layer of stacked structure will not generate bubbles due to material leakage or extrude the cavity structure due to material overflow.

[0094] The design of the layered co-extrusion die and the extrusion process ensure that each layer of stacked structure is tightly adhered when being covered, and there will be no bubbles or gaps between the interlayers. According to the principle deduction, the annular cavity polymer optical fiber with different cavity size structures can be designed to change the working wavelength window. In production, different designs and processes of the cavity size structure of the die can produce annular cavity polymer optical fibers with different working wavelength windows.

[0095] The embodiments of the present application provide a layered co-extrusion die and process for photonic bandgap polymer optical fiber or Bragg polymer optical fiber that have not been seen at home and abroad. According to the photonic bandgap principle and the Bragg reflection principle, the two kinds of special polymer optical fibers are analyzed from the structure of the optical fiber, combined with the actual production and equipment conditions, the concept of annular cavity polymer optical fiber is established, and the layered co-extrusion production process for this new type of optical fiber structure is proposed.

[0096] The embodiments of the present application can realize the continuous extrusion production of the annular cavity polymer optical fiber, prepare the annular cavity polymer optical fiber with excellent performance and stable structure, eliminate the cumbersome and difficult process steps in the preform rod drawing production mode, reduce the production difficulty and improve the production efficiency. The extrusion type production does not need to be processed into a preform rod, only needs to design and process a layered co-extrusion die, and the continuous extrusion production can be realized. The layered co-extrusion technology can monitor the stacked structure in the optical fiber cladding in real time, timely adjust the process parameters, and the production process is flexible and controllable.

[0097] The layered co-extrusion die proposed in the present application is to realize the continuous extrusion industrial production of the annular hollow polymer optical fiber. In some embodiments, the optical fiber cladding is a stack structure with periodically varying refractive index, which can confine the light of specific frequency and specific mode in the central refractive index defect layer, i.e. the hollow core layer, according to the photonic band gap theory and Bragg reflection principle. It can be deduced from the photonic band gap theory and Bragg reflection principle that the optical fiber with different stack structure sizes in the cladding can be applied to different working wavelengths. Therefore, by designing different dies, annular hollow polymer optical fibers with different structures can be produced, so that the optical fiber has excellent light guiding performance in the visible light band and even in the micron wave band.

[0098] In some embodiments, according to the above theory, the annular hollow polymer optical fiber produced by the process proposed in the present application can confine the light of specific frequency radially in the central hollow core layer, reduce the material absorption loss and the nonlinear effect of the optical fiber, and has good light guiding performance in various wavelength working bands.

[0099] The layered co-extrusion process can realize the continuous extrusion production of the annular hollow polymer optical fiber, ensure the stability of the product structure and performance, greatly improve the production efficiency and the price competitiveness of the product, eliminate the step of making the preform rod, make the optical fiber more controllable in the production process, and can timely find the deficiencies in the production process and timely modify, reduce the production accident rate and the product failure rate.

[0100] The present application also provides a method for preparing an optical cable, which comprises: preparing a polymer optical fiber according to the method provided in the above embodiments; and arranging a protective sleeve on the outer surface of at least one polymer optical fiber to obtain an optical cable. The optical fiber must be covered by several protective structures before use, and the cable after covering is called an optical cable. The optical cable of the present application comprises an annular hollow polymer optical fiber and a protective sleeve arranged on the outer surface of the annular hollow polymer optical fiber.

[0101] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; under the idea of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above, which are not provided in detail for simplicity; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A layered co-extrusion die for making a polymer optical fiber, characterized by, The polymer optical fiber comprises a core layer and a cladding layer, the cladding layer comprises a multilayer stack structure arranged in a radial direction of the polymer optical fiber from inside to outside, and at least two adjacent stack structures in the multilayer stack structure are stacked to form a plurality of spaced cavities, the multilayer stack structure comprises an Nth stack structure and an (N+1)th stack structure, wherein N 1 and N is a positive integer, when N 1, the Nth stack structure and the (N+1)th stack structure each comprise a ring-shaped polymer layer and a plurality of support strips, the plurality of support strips are distributed on one side of the ring-shaped polymer layer close to the Nth stack structure, the cavities are arranged between two adjacent support strips, the mold is used for preparing a fiber preform of the polymer optical fiber, and the fiber preform comprises a preformed hollow core layer and a preformed cavity. The mold comprises: a mold body comprising a plurality of annular components arranged in sequence from inside to outside, and a flow channel of polymer melt arranged between two adjacent annular components, wherein a cladding flow channel is used for passing a cladding polymer melt, and the cladding flow channel comprises an Nth flow channel and an (N+1)th flow channel; in the plurality of annular components, a plurality of hollow core columns extending along the axial direction of the annular components are arranged between at least two adjacent annular components, and the hollow core columns are distributed at intervals; in the process of preparing the optical fiber preform by using the mold, the side wall of the hollow core column is used to prevent the polymer melt from flowing into the inner cavity of the hollow core column to form the preform cavity, the Nth layer of polymer melt forms an Nth layer of preform stack structure after entering the Nth flow channel, and when the Nth layer of preform stack structure moves to the feeding area of the (N+1)th layer of polymer melt in the (N+1)th flow channel in the fiber drawing direction, the (N+1)th flow channel causes part of the (N+1)th layer of polymer melt to cover the Nth layer of preform stack structure to form a plurality of support strips, and part of the (N+1)th layer of polymer melt forms an (N+1)th layer of annular polymer on the side of the support strip away from the Nth layer of preform stack structure, wherein the feeding area of the (N+1)th layer of polymer melt is located at the front end of the fiber drawing direction relative to the feeding area of the Nth layer of polymer melt.

2. The mold of claim 1, wherein The core layer is a hollow core layer, and the hollow core layer is empty; the side wall of the innermost annular component in the plurality of annular components is used to prevent the polymer melt from flowing into the inner cavity of the innermost annular component to form the preform hollow core layer.

3. The mold of claim 2, wherein, The mold body is provided with a fiber outlet for outputting the optical fiber preform, and the mold further comprises a gas chamber arranged at the end of the mold body away from the fiber outlet; the gas chamber is used to: in the process of drawing the optical fiber preform, the gas is introduced into the preform cavity through the inner cavity of the hollow core column; and / or, the gas chamber is used to: in the process of drawing the optical fiber preform, the gas is introduced into the preform hollow core layer through the inner cavity of the innermost annular component.

4. The mold of claim 3, wherein The mold further comprises a gas pressure adjusting device arranged on the mold body; the gas pressure adjusting device is used to: in the process of drawing the optical fiber preform, the pressure of the first gas in the preform cavity is controlled within a preset first pressure range; and / or, in the process of drawing the optical fiber preform, the pressure of the second gas in the preform hollow core layer is controlled within a preset second pressure range.

5. The mold of claim 4, wherein, The gas pressure adjusting device comprises a temperature control device; the temperature control device is used to: in the process of drawing the optical fiber preform, the temperature of the mold body is controlled to adjust the pressure of the first gas and / or the second gas.

6. The mold of claim 4, wherein The mold further comprises a gas pressure sensor arranged on the mold body, and the gas pressure sensor is used to: in the process of drawing the optical fiber preform, the pressure of the first gas in the preform cavity is monitored; and / or, The air pressure sensor is configured to monitor the pressure of the second gas in the hollow core layer of the optical fiber preform during a drawing process of the optical fiber preform.

7. The mold of claim 1, wherein The optical fiber preform further comprises a pre-coated layer; The flow channel of the polymer melt further comprises a coating layer flow channel arranged outside the cladding flow channel, wherein the coating layer flow channel is configured to pass the polymer melt forming the coating layer; When the pre-cladding of the optical fiber preform runs to the feeding area of the coating melt, the polymer melt in the coating layer flow channel forms the pre-coated layer on the outer surface of the pre-cladding.

8. The mold of claim 1, wherein, The mold further comprises a plurality of metering pumps arranged on the mold body, each of the metering pumps is connected to the feeding port of each layer flow channel, and the metering pump is configured to control the flow rate of each layer of polymer melt entering the layer flow channel. The flow rate of each layer of the polymer melt is positively correlated with the cross-sectional area of the corresponding pre-stacking structure.

9. A polymer optical fiber production apparatus characterized by comprising: The production device comprises an extruder, an optical fiber drawing machine and the mold according to any one of claims 1-8, and the extruder, the mold and the optical fiber drawing machine are arranged in sequence. The extruder is configured to melt the polymer particles to form a polymer melt. The mold is configured to form an optical fiber preform by using the polymer melt. The optical fiber drawing machine is configured to draw the optical fiber preform to obtain the polymer optical fiber. The air pressure sensor is configured to monitor the pressure of the second gas in the hollow core layer of the optical fiber preform during a drawing process of the optical fiber preform. The optical fiber preform further comprises a pre-coated layer; The flow channel of the polymer melt further comprises a coating layer flow channel arranged outside the cladding flow channel, wherein the coating layer flow channel is configured to pass the polymer melt forming the coating layer; When the pre-cladding of the optical fiber preform runs to the feeding area of the coating melt, the polymer melt in the coating layer flow channel forms the pre-coated layer on the outer surface of the pre-cladding. The mold further comprises a plurality of metering pumps arranged on the mold body, each of the metering pumps is connected to the feeding port of each layer flow channel, and the metering pump is configured to control the flow rate of each layer of polymer melt entering the layer flow channel. The flow rate of each layer of the polymer melt is positively correlated with the cross-sectional area of the corresponding pre-stacking structure. The production device comprises an extruder, an optical fiber drawing machine and the mold according to any one of claims 1-8, and the extruder, the mold and the optical fiber drawing machine are arranged in sequence. The extruder is configured to melt the polymer particles to form a polymer melt. The mold is configured to form an optical fiber preform by using the polymer melt. The optical fiber drawing machine is configured to draw the optical fiber preform to obtain the polymer optical fiber.

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