Single-draw multi-step multi-furnace fabrication of hollow-core fibers

Abstract

A multi-stage draw tower may include: two or more draw furnaces associated with two or more draw stages; and one or more drawing devices to draw the preform through the two or more drawing stages. The two or more draw furnaces and the one or more pullers are configured to gradually reduce the diameter of the preform by one or more intermediate diameters to provide fibers having a selected final diameter in a single draw process. The fiber may correspond to a hollow-core optical fiber or a solid-core fiber.

Description

[0001] Government licensing rights This invention was made with Government support under Grant No. AFRL:FA86511820019 awarded by the U.S. Air Force Research Laboratory (AFRL) and Grant No. W911NF1910426 awarded by the U.S. Army Research Office (ARO). The Government has certain rights in this invention.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application Serial No. 63 / 422,776, filed on November 4, 2022, entitled SINGLE-DRAW MULTI-STEP MULTI-FURNACE FABRICATION OF HOLLOW-CORE FIBERS, inventors Rodrigo Amezcua-Correa, Jose Antonio-Lopez, Joseph Wahlen, and Stephanos Yerolatsitis, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates generally to the manufacture of optical fibers and, more particularly, to the manufacture of hollow core fibers using a single draw, multiple furnace technique. Background Art

[0004] Hollow-core optical fibers, which primarily guide light through air, offer several advantages over traditional glass fibers, including, but not limited to, high average and peak power capabilities, high damage thresholds, low latency, and relatively low nonlinearity. However, the manufacturing of hollow-core fibers presents unique challenges compared to traditional glass fibers, particularly when extended to long lengths. Therefore, there is a need to develop systems and methods that address these shortcomings. Summary of the Invention

[0005] According to one or more exemplary embodiments, a multi-stage draw tower is disclosed. In some embodiments, the multi-stage draw tower includes two or more draw furnaces associated with two or more draw stages. In some embodiments, the multi-stage draw tower includes one or more pullers for drawing a preform through the two or more draw stages, wherein the two or more draw furnaces and the one or more pullers are configured to gradually reduce the diameter of the preform through one or more intermediate diameters to provide a fiber having a selected final diameter in a single draw process.

[0006] In some embodiments, the multi-stage drawing tower includes a pressure system for applying pressure to the preform before the first of the two or more drawing stages. In some embodiments, the pressure system applies different pressures to different portions of the preform.

[0007] In some embodiments, the multi-stage draw tower includes one or more monitoring sensors to generate monitoring data associated with at least one of the preform or the fiber.

[0008] In some embodiments, the multi-stage draw tower includes a controller comprising one or more processors configured to execute program instructions that cause the one or more processors to perform various steps, such as, but not limited to, receiving the monitoring data from the one or more monitoring sensors or controlling at least one of the two or more draw furnaces or the one or more drawers via control signals based on the monitoring data. In some embodiments, controlling at least one of the two or more draw furnaces or the one or more drawers via control signals based on the monitoring data corresponds to controlling at least one of the one or more drawers based on the monitoring data to maintain a selected diameter of at least one of the preform or the fiber after a selected draw stage.

[0009] In some embodiments, the monitored data includes at least one of diameter, temperature, draw speed, tension, or geometry. In some embodiments, the monitored data includes pressure applied to the preform via a pressure system.

[0010] In some embodiments, the multi-stage draw tower includes a spool for receiving the fiber from the two or more draw stages.

[0011] In some embodiments, the multi-stage draw tower includes a coating system for applying one or more coatings to the fibers.

[0012] In some embodiments, a first draw furnace of the two or more draw furnaces is configured to accept the preform, wherein an allowable width of the preform accepted by the first draw furnace is equal to or greater than two centimeters, ten centimeters, or greater.

[0013] In some embodiments, the length of the optical fiber drawn from the preform by the two or more drawing stages is equal to or greater than five kilometers, fifty kilometers, or greater.

[0014] According to one or more exemplary embodiments, a method is disclosed. In some embodiments, the method includes placing a preform in a multi-stage draw tower. In some embodiments, the multi-stage draw tower includes: two or more draw furnaces associated with two or more draw stages; and one or more pullers for drawing the preform through the two or more draw stages. In some embodiments, the method includes performing a single draw process on the preform using the multi-stage draw tower, wherein the two or more draw furnaces and the one or more pullers are configured to gradually reduce the diameter of the preform through one or more intermediate diameters to provide a fiber having a selected final diameter in the single draw process.

[0015] In some embodiments, the method includes applying pressure to the preform with a pressure system before a first draw stage of the two or more draw stages. In some embodiments, applying pressure to the preform with a pressure system before the first draw stage of the two or more draw stages includes applying different pressures to different portions of the preform with the pressure system.

[0016] In some embodiments, the method includes generating monitoring data associated with at least one of the preform or the fiber using one or more monitoring sensors. In some embodiments, the method includes receiving the monitoring data from the one or more monitoring sensors and controlling at least one of the two or more draw furnaces or the one or more pullers via a control signal based on the monitoring data. In some embodiments, controlling at least one of the two or more draw furnaces, the one or more pullers, or the pressure system via a control signal based on the monitoring data includes controlling at least one of the one or more pullers based on the monitoring data to maintain a selected diameter of at least one of the preform or the fiber after a selected draw stage. In some embodiments, the monitoring data includes at least one of diameter, temperature, draw speed, tension, or geometry.

[0017] In some embodiments, the method includes applying one or more coatings to the fiber using a coating system.

[0018] According to one or more exemplary embodiments, a hollow-core optical fiber (HCF) is disclosed. In some embodiments, the HCF includes a cladding and one or more walled features within an internal cavity of the cladding, wherein the one or more walled features are configured to guide light of one or more selected wavelengths within a hollow central region of the internal cavity based on antiresonance. In some embodiments, the hollow-core optical fiber is formed by placing a preform in a multi-stage draw tower and performing a single draw process on the preform using the multi-stage draw tower, wherein the two or more draw furnaces and the one or more pullers are configured to gradually reduce the diameter of the preform through one or more intermediate diameters to provide a hollow-core optical fiber having a selected final diameter in the single draw process. In some embodiments, the width of the preform used to form the HCF is equal to or greater than two centimeters, ten centimeters, or greater. In some embodiments, the length of the HCF is equal to or greater than five kilometers, fifty kilometers, or greater.

[0019] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and do not necessarily limit the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the general description, serve to explain the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Those skilled in the art may better appreciate the numerous advantages of the present disclosure by referring to the accompanying drawings.

[0021] Figure 1 is a block diagram of a multi-stage draw tower according to one or more embodiments of the present disclosure.

[0022] Figure 2A is a simplified schematic diagram of a multi-stage drawing tower including three drawing stages according to one or more embodiments of the present disclosure.

[0023] Figure 2B is a simplified schematic diagram of a multi-stage draw tower including four draw stages to achieve a final diameter of a fiber, wherein the draw stages are not vertically aligned, according to one or more embodiments of the present disclosure.

[0024] Figure 3A is a cross-sectional view of a nested antiresonant hollow-core fiber design according to one or more embodiments of the present disclosure.

[0025] Figure 3B is a cross-sectional view of a nested antiresonant hollow-core fiber design according to one or more embodiments of the present disclosure.

[0026] Figure 3Cis a cross-sectional view of an antiresonant hollow-core fiber design with a split cylinder, according to one or more embodiments of the present disclosure.

[0027] Figure 3D is a cross-sectional view of a joint antiresonant hollow-core fiber design according to one or more embodiments of the present disclosure.

[0028] Figure 3E is a cross-sectional view of a nested antiresonant hollow-core fiber design according to one or more embodiments of the present disclosure.

[0029] Figure 3F is a cross-sectional view of a nested antiresonant hollow-core fiber design according to one or more embodiments of the present disclosure.

[0030] Figure 3G is a cross-sectional view of a nested antiresonant hollow-core fiber design according to one or more embodiments of the present disclosure.

[0031] Figure 3H is a cross-sectional view of a nested antiresonant hollow-core fiber design according to one or more embodiments of the present disclosure.

[0032] Figure 4 is a flow chart illustrating steps performed in a method for drawing a fiber according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION

[0033] Reference will now be made in detail to the disclosed subject matter as illustrated in the accompanying drawings. The present disclosure has been particularly shown and described with respect to certain embodiments and specific features thereof. The embodiments set forth herein are to be considered illustrative rather than restrictive. It will be readily apparent to those skilled in the art that various changes and modifications may be made in form and detail without departing from the spirit and scope of the present disclosure.

[0034] Embodiments of the present disclosure relate to systems and methods for manufacturing optical fibers using a multi-stage, single-draw process. As used herein, a draw process refers to a single operation of a draw tower that draws material from a preform into a new form with a diameter smaller than that of the preform. The resulting material can be in the form of an optical fiber (referred to herein as simply a fiber) or simply material with a diameter smaller than that of the preform (e.g., a cane, an intermediate preform, etc.). Furthermore, at the conclusion of the draw process, the resulting material is sufficiently cooled and can be removed from the draw tower as a final product or for further processing. A multi-draw process can then refer to multiple sequential operations of a draw tower (or multiple sequential operations of multiple draw towers) used to gradually reduce the diameter of a preform. The term "stage" is used herein to describe the process of drawing material from a certain diameter to a smaller diameter through heating and drawing. Thus, a draw process as contemplated herein can have one or more stages. For example, a single-stage single-draw process may correspond to a single operation of a drawing tower using a single drawing furnace to reduce the diameter of a preform from an initial diameter to a final diameter, while a multi-stage single-draw process may correspond to a single operation of a drawing tower using multiple drawing furnaces to gradually reduce the diameter of a preform from an initial diameter to a final diameter.

[0035] In various embodiments, a multi-stage fiber manufacturing system includes multiple drawing furnaces and / or pullers, each associated with a different stage, to gradually scale down the diameter of a preform to an optical fiber in a single draw. The use of multiple stages in a single draw process allows for precise control of various parameters of the preform at each stage, including but not limited to draw-down ratio (e.g., the ratio of the fiber diameter before and after a particular stage), tension, draw speed, cross-section, and / or temperature. The multi-stage fiber manufacturing system may also include sensors for monitoring the preform at any number of stages, which may be used to generate control signals for any component of the system at any stage. It is contemplated herein that the systems and methods disclosed herein may be particularly suitable for, but not limited to, hollow core fibers (HCF). The terms hollow core optical fiber, hollow core fiber, and antiresonant hollow core fiber are used interchangeably herein.

[0036] A typical process for manufacturing optical fibers may include first creating a preform having a diameter many times that of the desired fiber diameter, and then using the drawing process to scale down the diameter of the preform to form an optical fiber having the desired dimensions. For solid core fibers, the preform may typically be formed as a cylindrical rod having a diameter many times that of the desired fiber diameter. For HCF, the preform may typically be manufactured to provide the desired cross-section at the end of the drawing process. In either case, the drawing tower may also include additional components to anneal, cool, coat, cure, and / or wind the fiber as it is drawn.

[0037] In many applications, optical fibers are produced using a single-draw process with a single drawing stage. For example, a single-stage draw tower may have a single draw furnace (e.g., a single stage) and be designed to produce an optical fiber having a desired diameter directly from a preform. Such a single-stage, single-draw process can often be used to produce solid-core fiber, or HCF. However, as described in more detail throughout this disclosure, such techniques may have limitations on the length of fiber that can be produced, particularly when producing HCF.

[0038] The length of the fiber produced in a single draw can depend on the diameter and / or length of the preform, and therefore on the amount of material in the preform. The overall dimensions of the preform can vary depending on the type of process, the type of fiber to be produced, and / or the limitations of the draw tower, although it is generally desirable to provide a relatively large diameter to increase fiber production (e.g., the length of the finished fiber). As an example, silica-based fibers for telecommunications applications are typically produced using preforms having diameters ranging from about a few centimeters to about 20 cm and lengths ranging from about tens of centimeters to several meters, which can allow the production of thousands of kilometers of fiber in a single draw.

[0039] However, as contemplated herein, HCF faces various challenges that limit high-volume manufacturing (e.g., producing long lengths of HCF) when using a single-stage, single-draw process. For example, HCF preforms may be susceptible to collapse, expansion, and / or structural geometry changes (e.g., degradation) during the drawing process. Furthermore, HCF may require relatively high precision when controlling various aspects of the drawing process (such as, but not limited to, the tension, temperature, or pressure in any capillary used to form the hollow region). Consequently, there are practical limitations on the size of preforms (e.g., preform diameter) used to produce HCF using a single-stage, single-draw process.

[0040] Various embodiments of the present disclosure relate to the production of HCF using a multi-stage, single-draw process, wherein each stage has a separate draw furnace to reduce the diameter of the preform. This configuration enables a step-by-step drawing process and commensurate control of the drawing process for each stage. For example, the draw ratio at each stage (e.g., the ratio of fiber diameters before and after each stage) can be maintained at a level that promotes high-quality fibers and mitigates collapse, overexpansion, and / or structural degradation that can be detrimental to the performance of a fully produced HCF. Furthermore, the use of multiple draw stages as disclosed herein can allow the use of relatively large diameter preforms (e.g., up to 10 mm or greater) for producing relatively long fiber lengths (e.g., tens or hundreds of kilometers) in a single draw. In other words, the use of multiple draw stages as disclosed herein can allow the use of preforms with diameters larger than those permitted by a single-stage, single-draw process.

[0041] Any one of the stages can also include additional components for controlling the stretching process at each stage, such as, but not limited to, a dedicated puller. Additionally, the system can include monitoring equipment for monitoring the properties of the preform and / or fiber at any one of the stages, such as, but not limited to, a fiber geometry monitor, a diameter monitor, a temperature monitor, or a tension monitor. In addition, the monitoring equipment can monitor the operating parameters of any one of the following equipment, including, but not limited to, a drawing furnace, a puller, a reel, etc. The data from such monitoring equipment can then be used to feedback and / or feedforward control the associated stage and / or the process as a whole. In this way, the parameters of the fiber, such as, but not limited to, tension, diameter, fiber geometry, and temperature (e.g., based on draw rate, draw ratio, etc.), can be independently controlled.

[0042] It is further contemplated herein that the systems and methods disclosed herein may provide numerous advantages over alternative technologies for manufacturing HCF and may enable large-scale HCF manufacturing that is not possible or difficult to achieve using current technology.

[0043] For example, existing single-stage, single-draw HCF manufacturing techniques are limited to preform sizes of approximately a few centimeters in diameter (e.g., 1-3 cm) to maintain acceptable draw ratios and avoid collapse, excessive expansion, and / or structural deformation during the drawing process. For another example, existing single-stage, multi-draw techniques allow for some improvements in achievable fiber lengths, but suffer from high complexity and / or low throughput. In single-stage, multi-draw techniques, a preform is first drawn using a conventional single-stage draw process into one or more intermediate preforms having an intermediate diameter smaller than the preform but larger than the final diameter (e.g., approximately a few millimeters to a few centimeters). These intermediate preforms are often referred to as preforms. These intermediate preforms (e.g., preforms) can typically have any length, but in some cases are approximately 1-5 meters. The intermediate preforms can then be subsequently drawn using a second conventional single-stage draw process to form the final fiber. In some cases, the intermediate preforms are modified (e.g., inserted into additional tubes of material to increase the outer cladding thickness) prior to the second draw. However, the length of the final fiber may be limited by the diameter and / or length of each intermediate preform. In some cases, the length of the final fiber using such a single-stage, multiple-draw technique may be limited to several kilometers. In addition, such a technique is time-consuming and requires a separate drawing tower for each draw, or multiple towers for multiple draws.

[0044] In contrast, the systems and methods disclosed herein can be adapted to efficiently produce HCF having lengths of tens or hundreds of kilometers in a single draw from preforms having relatively large diameters (e.g., up to 10 cm or more). This is achieved, at least in part, by using multiple drawing stages to progressively reduce the fiber diameter through one or more intermediate diameters before reaching the desired diameter in a single draw.

[0045] It is further contemplated herein that the systems and methods disclosed herein can be adapted to any HCF fiber design and / or any material composition. Furthermore, the precise and gradual stretching provided by the systems and methods disclosed herein can enable the fabrication of more complex fiber designs (e.g., those that are more susceptible to collapse, overexpansion, or structural degradation) that are difficult or impossible to achieve using existing techniques.

[0046] Now refer to Figures 1-4 , according to one or more embodiments of the present disclosure, a system and method for manufacturing HCF are described in more detail.

[0047] Figure 1 is a block diagram of a multi-stage draw tower 100 according to one or more embodiments of the present disclosure. Figure 2Ais a simplified schematic diagram of a multi-stage drawing tower 100 including three drawing stages 102 according to one or more embodiments of the present disclosure. Figure 2A , the drawing stages 102 are individually labeled with the numbers 102-1, 102-2, and 102-3.

[0048] In some embodiments, the multi-stage draw tower 100 includes two or more draw stages 102, wherein each draw stage 102 includes at least one dedicated draw furnace 104 to reduce the diameter of the preform 202 at a selected draw ratio. In this manner, the draw stages 102 can gradually draw the preform 202 into a fiber 204 having a desired diameter (e.g., HCF). The multi-stage draw tower 100 may also include one or more spools 106 to collect and / or store the fiber 204 as it is drawn.

[0049] For the purposes of this disclosure, the term preform 202 is generally used to refer to the material placed into the multi-stage draw tower 100 and progressively drawn through one or more intermediate diameters. The term fiber 204 is generally used to refer to the material at its final diameter and is generally suitable for guiding light of one or more selected wavelengths. However, it should be understood that the terms preform 202 and fiber 204 are used herein merely as examples to describe the evolution of a material through the drawing process and should not be construed as imposing limitations on any properties of the associated materials, including, but not limited to, structural, chemical, and / or optical properties. In this manner, references to preform 202 or fiber 204 at any stage of the drawing process are merely illustrative and should not be construed as limiting. Unless explicitly stated, any reference herein to preform 202 may extend to fiber 204, and vice versa. In particular, references to monitoring one or more properties of preform 202 at any of the draw stages 102 may extend to monitoring one or more properties of fiber 204 after the final draw stage 102, and vice versa.

[0050] As an example, Figure 2A A preform 202 is depicted having a first diameter in the preform feeder 110 and upon entering the first draw stage 102-1. d 1, having a second diameter when leaving the first drawing stage and entering the second drawing stage 102-2 d 2, having a third diameter when leaving the second drawing stage 102-2 and entering the third drawing stage 102-3 d 3. Then, Figure 2A Depicted leaving the third drawing stage 102-3 having a fourth diameter d4. In this manner, it will be readily apparent that referring specifically to the material drawn through the multi-stage draw tower 100 as a preform 202 or a fiber 204 is merely conventional and does not limit the present disclosure.

[0051] The multi-stage draw tower 100 disclosed herein can be adapted to produce fibers 204 of any design, including, but not limited to, solid core fibers or HCFs. It is contemplated herein that the multi-stage draw tower 100 can be particularly advantageous for producing HCFs, including, but not limited to, antiresonant HCFs, in which light is guided in a hollow core due to the antiresonant properties of a thin-walled structure extending along the length of the fiber 204.

[0052] Now refer to Figure 3A-3H , depicts various non-limiting examples of fibers 204 that may be produced using the multi-stage draw tower 100. In particular, Figures 3A-3D Various antiresonant HCF designs are described. Antiresonant HCF designs are generally described in Md. Selim Habib et al., "Single-mode, low-loss hollow-core antiresonant fiber designs," Optics Express, Vol. 27, pp. 3824-3836 (2019), which is incorporated herein by reference in its entirety. For example, an antiresonant HCF can include a walled feature (e.g., a cylinder, tube, membrane, etc.) within an inner cavity of a cladding, wherein the walled feature guides light of one or more selected wavelengths within a hollow central region of the inner cavity based on optical antiresonance.

[0053] Figure 3A is a cross-sectional view of a nested antiresonant hollow core fiber 204 design according to one or more embodiments of the present disclosure. Figure 3A The design in includes a plurality (e.g., six) of hollow cylinders 302 (e.g., walled structures) distributed around an outer cylinder 304 (e.g., cladding) to form a central opening 306 (e.g., a hollow center region in which light is guided via optical antiresonance), wherein each of the cylinders 302 includes a nested cylinder 308.

[0054] Figure 3B is a cross-sectional view of a nested antiresonant hollow core fiber 204 design according to one or more embodiments of the present disclosure. Figure 3B The design in includes a rod 310 between cylinder 302 and cylinder 308 to provide for cylinder 308 to be centered within cylinder 302.

[0055] Figure 3C is a cross-sectional view of an antiresonant hollow core fiber 204 design with a split cylinder 302 according to one or more embodiments of the present disclosure. Figure 3CThe design in includes a membrane 312 (eg, a rod, an additional wall, etc.) that divides the cylinder 302 into two chambers with any size ratio.

[0056] Figure 3D is a cross-sectional view of a joint antiresonant hollow core fiber 204 design according to one or more embodiments of the present disclosure. Figure 3D The design in includes a pair of united cylinders 314a, 314b surrounding a central opening 306.

[0057] It should be understood that Figures 3A-3D are merely illustrative and should not be construed as limiting the designs of hollow core fibers 204 that may be produced using the multi-stage draw tower 100 as disclosed herein. As an example, Figure 3D-3H Describes one or more embodiments of the present disclosure. Figure 3A design variations.

[0058] Figure 3E is a cross-sectional view of a nested antiresonant hollow core fiber 204 design according to one or more embodiments of the present disclosure. Figure 3E The same as the Figure 3A The hollow core fibers 204 may include any number of groups of nested elements, such as, but not limited to, three, four, five, six, or more groups.

[0059] Figure 3F is a cross-sectional view of a nested antiresonant hollow core fiber 204 design according to one or more embodiments of the present disclosure. Figure 3F Except that each set of nested elements includes three cylinders (e.g., cylinder 302, cylinder 308, and cylinder 316), Figure 3E Generally similar. The hollow core fiber 204 can include any number of features within any group of nested elements. Additionally, the hollow core fiber 204 can include groups of nested elements having different designs.

[0060] Figure 3G and Figure 3H Depicts Figure 3E and Figure 3F A variation of FIG. 4 in which the thickness of the outer cylinder 304 (eg, cladding) is greater. Figure 3G is a cross-sectional view of a nested antiresonant hollow core fiber 204 design according to one or more embodiments of the present disclosure. Figure 3G Except that it includes a thicker outer cylinder 304 Figure 3E Generally similar. Figure 3H is a cross-sectional view of a nested antiresonant hollow core fiber 204 design according to one or more embodiments of the present disclosure. Figure 3HExcept that it includes a thicker outer cylinder 304 Figure 3F Hollow core fiber 204 may be of any thickness and may also include any number of additional structures.

[0061] exist Figure 3A-3H In the embodiment of the present invention, the anti-resonant properties of the walls of any of the features (eg, cylinder 302, cylinder 308, rod 312, cylinder 314, cylinder 316, etc.) can provide guidance of light in central opening 306. In addition, Figure 3A-3H The fiber 204 depicted in FIG2 can be manufactured based on a preform having any design or size suitable for producing the associated design after the drawing process. For example, the associated preform can have the same design as the depicted fiber 204, but with scaled dimensions. As another example, some features of the associated preform can have a different design than corresponding structures in the final fiber 204 to compensate for known or expected deviations caused by the drawing process. As an example, the relative diameter or thickness of any of the cylinders in preform 202 (e.g., cylinder 302, cylinder 308, cylinder 314, cylinder 316, etc.) can be larger or smaller than desired in the final fiber 204 to compensate for known or expected shrinkage or expansion during the drawing process.

[0062] The multi-stage drawing tower 100 disclosed herein may also be adapted to produce fibers 204 having any composition. For example, any component (e.g., Figure 3A-3H Cylinder 302, cylinder 304, cylinder 308, cylinder 314, cylinder 316, membrane 312, etc., depicted in the non-limiting design of FIG, can be formed from silica glass, doped silica glass, chalcogenide glass, fluoride glass, etc. Furthermore, any such component can be undoped or doped with one or more dopants. Additionally, fiber 204 can be formed from a single material or can have different components formed from different materials. For example, outer cylinder 304 (e.g., cladding) can be formed from a different material than any of the internal components (e.g., cylinder 304, cylinder 308, cylinder 314, cylinder 316, membrane 312, etc.). As another example, any of the internal components can be formed from a different material than the other internal components.

[0063] Additionally, it is contemplated herein that the multi-stage draw tower 100 may be adapted to produce any type of fiber 204, including, but not limited to, solid core fiber, photonic crystal fiber, or antiresonant HCF. Figure 3A-3H The examples in illustrative of some of the capabilities of multi-stage draw tower 100 are intended to illustrate, but not limit, multi-stage draw tower 100 .

[0064] Overall reference Figures 1-2B, additional aspects of the multi-stage draw tower 100 are described according to one or more embodiments of the present disclosure.

[0065] In some embodiments, the multi-stage draw tower 100 includes one or more drawers 108 to control the draw rate and / or tension of the preform 202 (or fiber 204) throughout the draw process. It is contemplated herein that the draw rate associated with any particular draw stage 102 (e.g., the current draw stage 102) can be selected based on considerations such as, but not limited to, the draw rate provided by the previous draw stage 102 (or, in the case of the first draw stage 102, the preform feeder 110), the temperature of the preform 202 entering the current draw stage 102, the tension on the preform 202 entering the current draw stage 102, the temperature of the draw furnace 104 of the current draw stage 102, or the desired draw ratio. Furthermore, the draw rate from one draw stage 102 becomes the feed rate into the subsequent draw stage 102.

[0066] The one or more pullers 108 may include any component or combination of components suitable for controlling the draw rate of the preform 202 (or fiber 204) at any draw stage 102, and may include, but is not limited to, one or more belts or one or more wheels. The pullers 108 may generally include components integrated into the one or more draw stages 102 and / or components external to any of the draw stages 102. For example, any draw stage 102 may have a dedicated puller 108, or component thereof, to individually control the draw rate at that draw stage 102. As another example, a multi-stage draw tower 100 may have one or more pullers 108 that can influence the draw rate of the preform 202 (or fiber 204) as a whole through the multi-stage draw tower 100. Figure 2A One non-limiting configuration is illustrated that includes the puller 108 as part of the first and second drawing stages 102, and the puller 108 (eg, capstan) after all of the drawing stages 102 and before the reel 106. However, this depiction is merely illustrative and not limiting.

[0067] The multi-stage draw tower 100 may generally have any number of draw stages 102. For example, the multi-stage draw tower 100 may have two, three, four, or more draw stages 102. Figure 1 A series of N drawing stages 102 are depicted, each drawing stage having a dedicated drawing furnace 104 . Figure 2A Depicted is a multi-stage drawing tower 100 comprising three drawing stages 102-1 to 102-3 configured to reduce the diameter of a preform 202 of material placed at the top of the multi-stage drawing tower 100 from an initial diameter to a diameter of d 1 gradually decreases to a final diameterd 4 fibers 204.

[0068] In some embodiments, the draw furnaces 104 of each draw stage 102 are arranged vertically so that the preform 202 can be drawn in a downward direction. However, this is not a requirement. Figure 2B is a simplified schematic diagram of a multi-stage drawing tower 100 including four drawing stages 102 to achieve a final diameter of a fiber 204 according to one or more embodiments of the present disclosure. d 5, wherein the drawing stages 102 are not vertically aligned. In addition to the arrangement of the drawing stages 102, Figure 2B and Figure 2A In general, Figure 2B A configuration is depicted in which the fourth draw stage 102-4 is laterally offset from the third draw stage 102-3. In this configuration, the multi-stage draw tower 100 includes an additional puller 108 to guide the preform 202 to the fourth draw stage 102-4. Notably, such a configuration may require that the preform 202 have a sufficiently small diameter between the third draw stage 102-3 and the fourth draw stage 102-4 to allow for manipulation without damage. For another example, although not shown, various additional components (such as, but not limited to, the monitoring sensor 118, the coating system 114, or the curing system 116) may be horizontally offset and / or arranged horizontally. In this configuration, the multi-stage draw tower 100 may include the puller 108 to manipulate the fiber 204 accordingly. Any of these configurations can reduce the overall height of the multi-stage draw tower 100 and the associated buildings or other structures surrounding it.

[0069] It is contemplated herein that different applications may benefit from different numbers of drawing stages 102 .

[0070] For example, increasing the number of draw stages 102 can reduce the draw ratio required at each draw stage 102 to achieve the desired diameter of the fiber 204. As a non-limiting example, a multi-stage draw tower 100 having two draw stages 102 can draw a 10 cm preform 202 to an intermediate diameter of 3 cm using a first draw stage 102, and then draw it to a final diameter of 300 micrometers (microns) using a second draw stage 102. As another non-limiting example, a multi-stage draw tower 100 having three draw stages 102 can draw a 10 cm preform 202 to a first intermediate diameter of 5 cm using a first draw stage 102, draw it to a second intermediate diameter of 1 cm using a second draw stage 102, and then draw it to a final diameter of 300 microns using a third draw stage 102. As another non-limiting example, a multi-stage draw tower 100 having three draw stages 102 can draw a 10 cm preform 202 to a first intermediate diameter of 5 cm using the first draw stage 102, draw it to a second intermediate diameter of 1 cm using the second draw stage 102, and then draw it to a final diameter of 125 microns using the third draw stage 102. In other words, increasing the number of draw stages 102 can enable an increase in the diameter and / or length of the preform 202 and, therefore, increase the total length of fiber 204 that can be produced in a single draw by maintaining an acceptable draw ratio at each draw stage 102. However, increasing the number of draw stages 102 can also increase the overall height (which can affect the required building space), cost, and complexity of the multi-stage draw tower 100. Therefore, the number of draw stages 102 in a given embodiment can be selected based on the requirements and goals of a particular application.

[0071] The draw furnace 104 in any draw stage 102 may include any component or combination of components suitable for heating preforms 202 and / or fibers 204 of any diameter. For example, the draw furnace 104 may include one or more heating elements (e.g., radiant heating elements, conductive heating elements, inductive heating elements, etc.) to heat the preform 202 at any draw stage 102. In this manner, the draw furnace 104 may control the temperature of the preform 202 to facilitate drawing at a desired draw rate and / or provide a desired draw ratio.

[0072] In some embodiments, the multi-stage draw tower 100 includes a preform feeder 110 for feeding preforms 20 into the first draw furnace 104. For example, the preform feeder 110 may include components for securing the preforms 202, such as, but not limited to, retainers, clips, springs, and the like. As another example, the preform feeder 110 may include components for positioning and / or lowering the preforms 202 into the first draw furnace 104, such as, but not limited to, one or more translation stages. Such components may position and / or lower the preforms 202 at a constant speed, a variable speed, or a dynamically controlled speed (e.g., based on feedback from a monitoring sensor 118, as described herein).

[0073] The draw furnaces 104 in different draw stages 102 can have the same or different configurations or operating parameters. For example, the draw furnaces 104 in different draw stages 102 can heat the preform 202 and / or fiber 204 to different temperatures, which can allow for customized control at each draw stage 102. Furthermore, the different draw furnaces 104 in different draw stages 102 can have different sizes and / or support structures based on the expected diameter of the fiber 204 at each draw stage 102. Additionally, the different draw furnaces 104 can have different sizes and / or hot zone profiles (e.g., the distribution of heating temperature along the drawing direction).

[0074] Additionally, although not shown, the multi-stage draw tower 100 may include one or more additional furnaces to provide additional processing functions beyond stretching the diameter of the preform 202. For example, the additional furnaces may be used to anneal the preform 202 at any of the draw stages 102 and / or to anneal the fibers 204 once they have reached a desired diameter.

[0075] In some embodiments, the multi-stage draw tower 100 includes a pressure system 112 to apply pressure to the preforms 202 (eg, at the preform feeder 110 ).

[0076] The pressure system 112 may include any component or combination of components suitable for applying pressure (or differential pressure) to the preform 202 and / or fiber 204 at any draw stage 102 and may include, but is not limited to, a pressure manifold or components that provide active pressure control. As an example, Figure 2A and Figure 2B A pressure system 112 is depicted having multiple pressure manifolds 206 to apply different pressures to different portions of the fibers 204 and / or preform 202. As an example, in a system having Figure 3FIn the case of hollow-core fiber 204 of the design shown in FIG, pressure system 112 may include pressure manifold 206 to individually control the pressure in different hollow regions, such as, but not limited to, the pressure within cylinder 316, between cylinder 308 and cylinder 316, between cylinder 302 and cylinder 308, or within central lumen 306. However, in some embodiments, a constant pressure may be applied to all portions of fiber 204.

[0077] Pressure system 112 can generally apply positive pressure to any region, apply negative pressure (e.g., a vacuum) to any region, or control differential pressure between any regions. Furthermore, pressure system 112 can control the composition of the gas within any hollow region of fiber 204. In some embodiments, pressure system 112 fills one or more hollow regions with a gas of a selected composition, such as, but not limited to, nitrogen, argon, or any inert gas. In some embodiments, pressure system 112 fills one or more hollow regions with ambient atmosphere (or allows the hollow regions to be filled with ambient atmosphere).

[0078] In some embodiments, the multi-stage draw tower 100 includes a coating system 114 for coating the fibers 204 after the fibers 204 have reached a desired diameter. The coating system 114 can include any component or combination of components suitable for coating the fibers 204. For example, the coating system 114 can include one or more containers with a coating fluid (e.g., a polymer, an acrylate, or any suitable compound) through which the fibers 204 can pass such that the coating fluid surrounds the fibers 204. The coating system 114 can provide multiple coatings of the same or different materials.

[0079] In some embodiments, the multi-stage draw tower 100 includes a curing system 116 for curing one or more coatings on the fibers 204. The curing system 116 may include any component or combination of components suitable for curing the fibers 204 and / or one or more coatings on the fibers 204. For example, the curing system 116 may include, but is not limited to, one or more light sources or one or more heat sources. As an example, the curing system 116 may include one or more ultraviolet (UV) light sources or one or more curing ovens.

[0080] In some embodiments, multi-stage draw tower 100 includes one or more monitoring sensors 118 for monitoring one or more aspects of preform 202, fiber 204, any of draw stages 102, and / or the multi-stage draw tower as a whole. Monitoring sensors 118 may include any component or combination of components suitable for monitoring preform 202, fiber 204, any of draw stages 102, and / or the multi-stage draw tower 100 as a whole, such as, but not limited to, one or more sensors. Furthermore, monitoring sensors 118 (or components thereof) may be distributed throughout multi-stage draw tower 100 in any manner and may optionally be integrated into any of draw stages 102.

[0081] For example, the monitoring sensors 118 may include one or more diameter sensors for monitoring the diameter of the preform 202 (or fiber 204) at any point. For another example, the monitoring sensors 118 may include one or more speed sensors for monitoring the drawing speed of the preform 202 (or fiber 204) at any point. For another example, the monitoring sensors 118 may include one or more temperature sensors for monitoring the temperature of the preform 202 (or fiber 204) at any point. For another example, the monitoring sensors 118 may include one or more tension sensors for monitoring the tension of the preform 202 (or fiber 204) at any point. For another example, the monitoring sensors 118 may include one or more sensors for monitoring the internal geometry of the preform 202 (or fiber 204) at any point. For another example, the monitoring sensors 118 may include one or more sensors for monitoring the pressure applied to the preform 202 by the pressure system 112 and / or the relative pressures applied to various portions of the preform 202. As another example, the monitoring sensors 118 may include one or more sensors to monitor coating application pressure, temperature, and / or diameter of one or more coatings on the fiber 204 .

[0082] As another example, monitoring sensors 118 may include one or more sensors for monitoring any component of multi-stage draw tower 100, such as, but not limited to, draw furnace 104, one or more pullers 108, pressure system 112, coating system 114, or curing system 116. In this way, the efficiency and / or operating status of the components of multi-stage draw tower 100 may be monitored and action taken as appropriate. As an example, monitoring sensors 118 may include various sensors at each draw stage 102 (or at least some of the draw stages 102) to monitor any selected property of preform 202 and / or fiber 204, such as, but not limited to, diameter, internal geometry, draw speed, temperature, tension, or any other suitable property.

[0083] In various embodiments, the multi-stage draw tower 100 includes a controller 120 communicatively coupled to any components therein. In some embodiments, the controller 120 includes one or more processors 122 configured to execute a set of program instructions maintained in a memory 124 or a storage device. The one or more processors 122 of the controller 120 may include any processing element known in the art. In this sense, the one or more processors 122 may include any microprocessor-type device configured to execute algorithms and / or instructions. For the purposes of this disclosure, the term "processor" or "processing element" may be broadly defined to include any device having one or more processing or logic elements (e.g., one or more microprocessor devices, one or more application specific integrated circuit (ASIC) devices, one or more field programmable gate arrays (FPGAs), or one or more digital signal processors (DSPs)).

[0084] In some embodiments, the one or more processors 122 are formed as, or integrated into, a desktop computer, a mainframe computer system, a workstation, a graphics computer, a parallel processor, a networked computer, or any other computer system configured to execute program instructions. Furthermore, the steps described throughout this disclosure may be performed by a single controller, or alternatively, by multiple controllers. Additionally, the controller 120 may include one or more controllers housed within a common housing or multiple housings.

[0085] The memory 124 may comprise any storage medium known in the art suitable for storing program instructions executable by the associated processor(s) 122. For example, the memory 124 may comprise a non-transitory storage medium. By way of another example, the memory 124 may include, but is not limited to, read-only memory (ROM), random access memory (RAM), magnetic or optical storage devices (e.g., disks), tape, solid-state drives, and the like. It should also be noted that the memory 124 may be housed in a common controller housing along with the processor(s) 122. In some embodiments, the memory 124 may be remotely located relative to the physical location of the processor(s) 122 and the controller 120. For example, the processor(s) 122 of the controller 120 may access remote storage (e.g., a server) accessible via a network (e.g., the Internet, an intranet, etc.).

[0086] In various embodiments, the multi-stage draw tower 100 includes a user interface 126 communicatively coupled to the controller 120. In one embodiment, the user interface 126 may include, but is not limited to, one or more desktop computers, laptop computers, tablet computers, and the like. In another embodiment, the user interface 126 includes a display for displaying data to a user. The display of the user interface 126 may include any display known in the art. For example, the display may include, but is not limited to, a liquid crystal display (LCD), an organic light emitting diode (OLED)-based display, or a CRT display. Those skilled in the art will recognize that any display device capable of being integrated with the user interface 126 is suitable for implementation within the present disclosure. In another embodiment, a user may input selections and / or commands via a user input device of the user interface 126 in response to data displayed to the user.

[0087] The controller 120 can be communicatively coupled to any component of the multi-stage draw tower 100, such as, but not limited to, the preform feeder 110, the pressure system 112, the draw furnace 104, the puller 108, the coating system 114, the curing system 116, the monitoring sensors 118, or the user interface 126. In this manner, the controller 120 can direct the operation of any such component (e.g., via control signals) and / or receive data from any such component. For example, the controller 120 can initialize and / or direct the operation of any of the components using parameters suitable for drawing a particular fiber 204 based on parameters such as, but not limited to, the design, composition, or dimensions of the preform 202. For another example, the controller 120 can receive monitoring data from the monitoring sensors 118 (e.g., monitoring sensors associated with the preform feeder 110, the pressure system 112, any of the draw stages 102, any of the pullers 108, or the drawing process as a whole). In this manner, the monitoring data can be used for feedback and / or feedforward control of the drawing process. As an example, the controller 120 can adjust any operating parameter of any of the components of the multi-stage draw tower 100 to ensure that the current fiber 204 is manufactured within the tolerance of the length of the fiber 204 using feedback control techniques. As another example, the controller 120 can adjust any operating parameter of any of the drawing stages 102 and / or components to ensure that future fibers 204 of similar design are manufactured within the tolerance based on data obtained from one or more previously manufactured fibers 204.

[0088] In some embodiments, the controller 120 implements (e.g., via the processor 122) any number or type of control loops based on data from one or more monitoring sensors 118 through feedforward and / or feedback. Specifically, the controller 120 can generate control signals to adjust any component of the multi-stage draw tower 100. For example, the controller 120 can receive data from the monitoring sensors 118 regarding the diameter of the preform 202 at one draw stage 102 (e.g., the second draw stage 102-2) and dynamically adjust the drawer 108 to control the feed rate after the previous draw stage 102 (e.g., the first draw stage 102-1). More generally, because the draw rate at one draw stage 102 is the feed rate at the subsequent draw stage 102, the controller 120 can dynamically control the draw rate / feed rate across all stages to maintain a desired draw ratio and / or diameter at each draw stage 102. As another example, the controller 120 may receive diameter and / or geometry measurements from the monitoring sensors 118 and dynamically adjust the pressure system 112 to adjust the pressure applied to any one of the regions of the preform 202. In this manner, the controller 120 may maintain a desired diameter and / or geometry profile and thereby mitigate collapse, over-inflation, structural degradation, etc.

[0089] Now, the overall reference Figures 1-2B It is contemplated herein that the multi-stage draw tower 100 can be operated in different modes. In this manner, a particular design or embodiment of the multi-stage draw tower 100 can be flexibly used to produce a wide range of fibers 204.

[0090] In some embodiments, one or more draw stages 102 can be selectively operated or dormant during a given draw. For example, not all applications or compositions may require or benefit from all available draw stages 102 of a particular embodiment of a multi-stage draw tower 100. In such cases, one or more draw stages 102, or portions thereof, can be selectively dormant during a draw. In this manner, a multi-stage draw tower 100 having three draw stages 102 can operate with only two draw stages 102 (or even a single draw stage 102) for a given draw. In this manner, a multi-stage draw tower 100 can be configurable for a wide range of solid and / or hollow core designs or applications.

[0091] In some embodiments, the monitoring sensors 118 include one or more actuators and / or translation stages for adjusting the absolute or relative position of any of the components. For example, the relative spacing between any of the drawing stages 102 can be adjusted to provide additional control over parameters of the fiber 204, including but not limited to diameter, temperature, or tension.

[0092] Figure 4 is a flow chart illustrating the steps performed in a method 400 for drawing a fiber 204 according to one or more embodiments of the present disclosure. Applicants note that the embodiments and implementation techniques previously described herein in the context of a multi-stage draw tower 100 should be interpreted as extending to the method 400. However, it is also noted that the method 400 is not limited to the architecture of a multi-stage draw tower 100.

[0093] In some embodiments, the method 400 includes a step 402 of placing the preform 202 in a multi-stage draw tower (eg, the multi-stage draw tower 100 ).

[0094] In some embodiments, method 400 includes step 404 of performing a single draw process on preform 202 using multi-stage draw tower 100, wherein two or more draw furnaces 104 and / or one or more pullers 108 of multi-stage draw tower 100 gradually reduce the diameter of preform 202 through one or more intermediate diameters to provide fiber 204 having a selected final diameter through the single draw process.

[0095] It is contemplated herein that method 400 may be adapted to draw relatively long lengths of fiber 204 in a single draw by sequentially reducing the diameter of preform 202 using two or more draw stages 102. For example, preform 202 may have any suitable diameter, including but not limited to 2 cm, 3 cm, 5 cm, 10 cm, 15 cm, or larger, which may provide fiber lengths on the order of tens, hundreds, or potentially thousands of kilometers. It is further contemplated herein that such fiber lengths may be achieved using any design of fiber 204, including but not limited to HCF. For example, if the draw ratio at any given draw stage is too high, HCF may be particularly susceptible to collapse, overexpansion, and / or deformation. However, using multiple draw stages 102 to sequentially reduce the diameter of fiber 204 may allow the draw ratio to be maintained at a suitable level for each draw stage 102, while still allowing the mass production of long fiber lengths in a single draw using large diameter preforms 202.

[0096] In some embodiments, the method 400 further includes generating monitoring data associated with the fiber 204 after any of the two or more drawing stages 102. For example, the monitoring data may include, but is not limited to, data associated with the diameter, temperature, drawing speed, or tension of the fiber 204. Such monitoring data may be used for feedback and / or feedforward control.

[0097] The subject matter described herein sometimes illustrates the different parts that are contained in other parts or are connected with other parts.Should be understood that the architecture of such description is only exemplary, and in fact can implement many other architectures realizing the same function.In the sense of concept, any arrangement in order to realize the parts of the same function is effectively "associated", so that the desired function is realized.Therefore, any two parts that are combined to realize a specific function in this article can be regarded as "associated" to each other, so that the desired function is realized, and no matter how the architecture or intermediate parts are.Similarly, any two parts that are so associated can also be regarded as "connected" or "coupled" to realize the desired function, and any two parts that can be so associated can also be regarded as "coupling" to realize the desired function.The specific example that can be coupled includes but is not limited to physically interactive and / or physically interactive parts and / or wirelessly interactive and / or wirelessly interactive parts and / or logically interactive and / or logically interactive parts.

[0098] It is believed that the present disclosure and its many attendant advantages will be appreciated from the foregoing description, and it will be apparent that various changes may be made in the form, construction, and arrangement of the components without departing from the disclosed subject matter or sacrificing all of its substantial advantages. The forms described are illustrative only, and it is intended that such changes be encompassed by the following claims. Furthermore, it should be understood that the invention is defined by the appended claims.

Claims

1. A multi-stage drawing tower comprising: two or more drawing furnaces associated with two or more drawing stages; and One or more pullers for drawing the preform through the two or more drawing stages, wherein the two or more drawing furnaces and the one or more pullers are configured to gradually reduce the diameter of the preform through one or more intermediate diameters to provide a fiber having a selected final diameter in a single drawing process.

2. The multi-stage drawing tower according to claim 1, further comprising: A pressure system is configured to apply pressure to the preform prior to a first of the two or more draw stages.

3. The multi-stage drawing tower according to claim 2, wherein: The pressure system applies different pressures to different parts of the preform.

4. The multi-stage drawing tower according to claim 1, further comprising: One or more monitoring sensors configured to generate monitoring data associated with at least one of the preform or the fiber.

5. The multi-stage draw tower of claim 4 , further comprising a controller comprising one or more processors configured to execute program instructions that cause the one or more processors to: receiving the monitoring data from the one or more monitoring sensors; and At least one of the two or more draw furnaces or the one or more pullers is controlled via a control signal based on the monitoring data.

6. The multi-stage drawing tower according to claim 5, wherein: Controlling at least one of the two or more draw furnaces or the one or more pullers via a control signal based on the monitoring data includes: At least one of the one or more drawers is controlled via a control signal based on the monitoring data to maintain a selected diameter of at least one of the preform or the fiber after a selected drawing stage.

7. The multi-stage drawing tower according to claim 4, wherein: The monitoring data includes: At least one of diameter, temperature, draw speed, tension, or geometry.

8. The multi-stage drawing tower according to claim 7, further comprising: A pressure system is configured to apply pressure to the preform prior to a first of the two or more draw stages, wherein the monitoring data further includes the pressure applied to the preform.

9. The multi-stage drawing tower according to claim 8, further comprising: A controller comprising one or more processors configured to execute program instructions that cause the one or more processors to: receiving the monitoring data from a monitoring system; and At least one of the two or more draw furnaces, the one or more pullers, or the pressure system is controlled via a control signal based on the monitoring data.

10. The multi-stage drawing tower according to claim 1, further comprising: A spool is provided for receiving the fiber from the two or more drawing stages.

11. The multi-stage drawing tower of claim 1 , further comprising: A coating system is provided for applying one or more coatings to the fibers.

12. The multi-stage drawing tower according to claim 1, wherein: The two or more drawing stages include three or more drawing stages.

13. The multi-stage drawing tower according to claim 1, wherein: The fibers include: Hollow fiber.

14. The multi-stage drawing tower according to claim 13, wherein: A first draw furnace of the two or more draw furnaces is configured to accept the preform, wherein an allowable width of the preform accepted by the first draw furnace is equal to or greater than two centimeters.

15. The multi-stage drawing tower according to claim 13, wherein: A first draw furnace of the two or more draw furnaces is configured to accept the preform, wherein an allowable width of the preform accepted by the first draw furnace is equal to or greater than ten centimeters.

16. The multi-stage drawing tower according to claim 13, wherein: The length of the optical fiber drawn from the preform through the two or more drawing stages is equal to or greater than five kilometers.

17. The multi-stage drawing tower according to claim 13, wherein: The length of the optical fiber drawn from the preform through the two or more drawing stages is equal to or greater than fifty kilometers.

18. A method comprising: The preform is placed in a multi-stage drawing tower, wherein the multi-stage drawing tower comprises: two or more drawing furnaces associated with two or more drawing stages; and one or more pullers for drawing the preform through the two or more drawing stages; and The preform is subjected to a single drawing process using the multi-stage drawing tower, wherein the two or more drawing furnaces and the one or more pullers are configured to gradually reduce the diameter of the preform through one or more intermediate diameters to provide a fiber having a selected final diameter in the single drawing process.

19. The method according to claim 18, further comprising: Pressure is applied to the preform with a pressure system prior to a first of the two or more draw stages.

20. The method according to claim 19, wherein Applying pressure to the preform with a pressure system prior to a first of the two or more draw stages includes: Different pressures are applied to different parts of the preform using the pressure system.

21. The method of claim 18, further comprising: Monitoring data associated with at least one of the preform or the fiber is generated using one or more monitoring sensors.

22. The method according to claim 21, further comprising: receiving the monitoring data from the one or more monitoring sensors; and At least one of the two or more draw furnaces or the one or more pullers is controlled via a control signal based on the monitoring data.

23. The method according to claim 22, wherein Controlling at least one of the two or more draw furnaces or the one or more pullers via a control signal based on the monitoring data includes: At least one of the one or more drawers is controlled via a control signal based on the monitoring data to maintain a selected diameter of at least one of the preform or the fiber after a selected drawing stage.

24. The method according to claim 21, wherein The monitoring data includes: At least one of diameter, temperature, draw speed, tension, or geometry.

25. The method according to claim 24, further comprising: A pressure system is used to apply different pressures to different parts of the preform.

26. The method according to claim 25, further comprising: receiving the monitoring data from a monitoring system; and At least one of the two or more draw furnaces, the one or more pullers, or the pressure system is controlled via a control signal based on the monitoring data.

27. The method of claim 18, further comprising: The fibers are coated with one or more coatings using a coating system.

28. The method according to claim 18, wherein The two or more drawing stages include three or more drawing stages.

29. The method according to claim 18, wherein The fibers include: Hollow fiber.

30. The method according to claim 29, wherein A first draw furnace of the two or more draw furnaces is configured to accept the preform, wherein an allowable width of the preform accepted by the first draw furnace is equal to or greater than two centimeters.

31. The method according to claim 29, wherein A first draw furnace of the two or more draw furnaces is configured to accept the preform, wherein an allowable width of the preform accepted by the first draw furnace is equal to or greater than ten centimeters.

32. The method of claim 29, wherein: The length of the optical fiber drawn from the preform through the two or more drawing stages is equal to or greater than five kilometers.

33. The method of claim 29, wherein: The length of the optical fiber drawn from the preform through the two or more drawing stages is equal to or greater than fifty kilometers.

34. A hollow-core optical fiber comprising: cladding; One or more wall features within the inner cavity of the cladding, wherein the one or more wall features are configured to guide one or more selected wavelengths of light within a hollow central region of the inner cavity based on antiresonance, wherein the hollow core optical fiber is formed by: The preform is placed in a multi-stage drawing tower, wherein the multi-stage drawing tower comprises: two or more drawing furnaces associated with two or more drawing stages; and one or more pullers for drawing the preform through the two or more drawing stages; and The preform is subjected to a single drawing process using the multi-stage drawing tower, wherein the two or more drawing furnaces and the one or more pullers are configured to gradually reduce the diameter of the preform through one or more intermediate diameters to provide the hollow-core optical fiber having a selected final diameter in the single drawing process.

35. The hollow core optical fiber of claim 34, wherein: The preform has a width equal to or greater than two centimeters.

36. The hollow core optical fiber of claim 34, wherein: The width of the preform is equal to or greater than ten centimeters.

37. The hollow core optical fiber of claim 34, wherein: The length of the hollow core optical fiber drawn from the preform through the two or more drawing stages is equal to or greater than five kilometers.

38. The hollow core optical fiber of claim 34, wherein: The length of the hollow core optical fiber drawn from the preform through the two or more drawing stages is equal to or greater than fifty kilometers.

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