Signal beam combiner and preparation method

Abstract

The invention discloses a signal beam combiner and a preparation method. The signal beam combiner comprises a plurality of input optical fibers and an output optical fiber welded with a cone formed by combining and tapering the input optical fibers. The input optical fiber is sleeved with an inner sleeve, and the middle section of the inner sleeve is removed to form a pipe knocking area after the inner sleeve is tapered, so that the cone part of the input optical fiber in the inner sleeve is exposed; etching areas are arranged on the two sides of a fusion point between the output optical fiber and the input optical fiber cone, so that cladding light of the input optical fiber can be scattered through the pipe knocking area and the etching areas. By arranging the pipe knocking area and the etching area to scatter cladding light, the problem of high temperature of the conical area of the signal beam combiner is solved at low cost.

Description

Technical Field

[0001] The present invention relates to the field of laser technology, and in particular to a signal beam combiner and a preparation method thereof. Background Art

[0002] The actual heating conditions of the cone area of ​​the signal combiner and the main reasons for performance degradation in high-temperature environments can be summarized into the following four categories: 1. The laser energy is converted into thermal energy in the combiner material, resulting in physical changes caused by local temperature increase, that is, thermal effect. The causes of thermal effect are as follows: ① Material thermal expansion: The thermal expansion coefficients of different materials (such as optical fiber core / cladding, adhesive) do not match, resulting in mechanical stress, leading to structural deformation or microcracks; ② Refractive index thermal drift: The temperature increase causes the refractive index of the material to change (dn / dT effect), destroying the original optical path design (such as causing beam deflection or mode mismatch); ③ Thermal lens effect: The temperature gradient forms a lens-like refractive index distribution, causing the beam to focus / diverge (common in high-power solid-state laser combining). 2. At high power densities, the interaction between light and the medium produces inelastic scattering or phase modulation effects, i.e., nonlinear effects. The internal mechanisms that cause these nonlinear effects are: stimulated Brillouin scattering, stimulated Raman scattering, and self-phase modulation. Increasing temperature reduces the nonlinear threshold. For example, the stimulated Brillouin scattering gain coefficient increases with temperature, making the nonlinear effect more easily triggered. 3. High-energy photons directly damage the atomic / molecular structure of the material, or heat accumulation leads to melting / ablation. This includes intrinsic damage when the photon energy is greater than the material's band gap; impurity damage caused by metal ions, dust, and other contaminants absorbing light energy to form hot spots with temperatures reaching 3000°C, melting the fiber end face; and thermal damage caused by continuous heat accumulation, which causes materials such as quartz glass to reach ultra-high melting points. 4. At high power, thermal effects trigger dynamic coupling of transmission modes in the optical fiber, resulting in random jitter in the output light intensity and pointing direction, making the optical transmission mode unstable.

[0003] For signal combiners, high temperatures in the taper region are a major issue affecting the stability of the internal environment. The causes of high temperatures in the taper region can be explained from the perspective of optical, thermal, and mechanical multi-physics coupling. First, mode mismatch is caused by core distortion during the taper process. When the fiber is heated and stretched, the core typically changes from a circular shape to a smaller one, but it can also change from a circular shape to an elliptical or even dumbbell shape. This disrupts the original waveguide conditions and causes the core light to leak into the cladding. Secondly, "cladding light accumulation" occurs, which disrupts the total internal reflection condition. The normal critical angle of the cladding / air interface is approximately 82°. However, if the following conditions exist: ① contamination at the ferrule interface (a sudden change in refractive index), ② thermal damage (microcracks) to the fiber cladding, or ③ an excessively small bend radius in the taper region, the critical angle increases, allowing light that should have been confined to escape outside the cladding, concentrating the light leakage in the problematic area. Finally, when the fiber coating is squeezed by external forces, micropores form at the interface with the cladding, allowing the cladding light to leak into the optical trapping region, generating heat. In terms of quantitative impact, experimental data shows that the cone temperature and stray light power exhibit a linear relationship, T = 25 + 0.18P-stray. For example, when there is 10W of stray light, the theoretical temperature rise can reach 205°C. In a high-temperature positive feedback loop, the temperature rises, the quartz refractive index changes (dn / dT = 1.2 × 10-5 / K), and more light leaks, which in turn leads to a further temperature rise. This situation is inherent in the fabrication of signal combiners. Uniformly scattering the cladding light or reducing the transmission of cladding stray light, thereby lowering the temperature in the combiner's core region and stabilizing the internal thermal environment, is a crucial issue for laser core components. This invention, by modifying the combiner's structure and packaging environment, provides a low-cost heat dissipation method for the combiner: uniform cladding light scattering + air dielectric heat dissipation. This method strips away most of the cladding stray light from the combiner. Furthermore, by knocking the tube, the cladding light is evenly scattered directly into the air. A water cooling system continuously removes heat from the air, ensuring a stable temperature in the combiner's core region and stable power output.

[0004] The occurrence of high temperature in existing signal combiners has always been subject to some restrictive factors such as thermal effects, nonlinear effects, optical damage and mode instability. These factors continue to appear in multiple composite forms as the power increases, becoming a bottleneck for further improvement of fiber laser power. The existing cooling methods in the industry include the following treatment methods: 1. Passive heat dissipation enhancement, such as the metal or ceramic heat sink fins + thermal grease mentioned in patent CN113640958A. Its core defect is that it only delays heat conduction and cannot solve the source of cladding light accumulation. In addition, the grease ages at high temperatures. 1. Active cooling package, such as the method of wrapping the cone area with a water-cooling sleeve as described in patent US20210033821A1, still has the problem of coolant absorbing heat, but the flow causes the refractive index of the combiner to be disturbed, exacerbating the problem of light leakage; 2. Perform cladding light stripping, such as shown in patent JP2020154287A, and coat the cone area with a high refractive index polymer. However, this method is highly dependent on the polymer. The polymer is easily carbonized after long-term treatment in a high-temperature environment of >150°C. After failure, the polymer easily becomes a heat source and burns at high temperature when the stripping efficiency drops sharply. Summary of the Invention

[0005] The object of the present invention is to provide a signal combiner and a preparation method to partially solve or alleviate the above-mentioned deficiencies in the prior art, and to scatter the cladding light in the air, thereby solving the high temperature problem in the cone region of the signal combiner in a low-cost manner.

[0006] In order to solve the above-mentioned technical problems, the present invention specifically adopts the following technical solutions: A first aspect of the present invention is to provide a signal combiner, comprising a plurality of input optical fibers and an output optical fiber fused to a cone formed by combining and tapering the plurality of input optical fibers; the input optical fibers are outer-coated with an inner sleeve, and after tapering, the middle section of the inner sleeve is removed to form a knock-tube region, thereby exposing the input optical fiber cone within the inner sleeve; etched regions are provided on both sides of the fusion point between the output optical fiber and the input optical fiber cone, so that the cladding light of the input optical fiber can be scattered through the knock-tube region and the etched region.

[0007] Furthermore, the etched area on the input optical fiber is adjacent to the fusion splice point; and a blank area is directly provided between the etched area and the fusion splice point on the output optical fiber.

[0008] Furthermore, the straight section of the input optical fiber cone is fully etched to form an etched area; the length of the etched area on the output optical fiber is 9-11 mm, and the length of the blank area is 6-8 mm.

[0009] Furthermore, the ratio of the inner casing knocking area to the overall length of the inner casing is 1:15 to 1:5.

[0010] Furthermore, it also includes an outer sleeve sleeved on the tail end of the input optical fiber, and the outer sleeve partially overlaps with the inner sleeve; the two ends of the outer sleeve are respectively bonded and fixed to the input optical fiber and the inner sleeve by glue.

[0011] Furthermore, it also includes an alumina structural member for encapsulating the signal combiner; a sapphire glass groove for placing the signal combiner and a glass cover for sealing the signal combiner are fixed in the alumina structural member; the alumina structural member dissipates heat through a water cooling plate.

[0012] The present invention also provides a method for preparing a signal combiner, which is used to prepare the above-mentioned signal combiner, comprising: Tapering: inserting several input optical fibers into an inner sleeve, heating and stretching the inner sleeve and the input optical fibers to form a cone on the input optical fibers, and removing the end of the cone that is not connected to the input optical fibers; Knock the pipe once, break the inner casing and make a temporary connection at the fracture; Assemble the outer sleeve, put the outer sleeve on the tail end of the input optical fiber, and insert the inner sleeve part into the outer sleeve; use glue to bond the two ends of the outer sleeve to the input optical fiber and the inner sleeve respectively; Etching: After the input fiber cone and the output fiber are fused together, etching is performed on the straight section of the input fiber cone and the output fiber to form an etched area; Secondary knocking: the inner tube is broken a second time to form a new fracture, and the temporary connection during the first knocking is disconnected; the free inner tube section formed by the second break is then crushed to form a knocking area to obtain the semi-finished signal combiner; The semi-finished signal combiner is packaged and fixed in a sapphire glass groove in an alumina structural component, and a water cooling plate is used for heat dissipation.

[0013] Furthermore, when tapering, the corrosion transition zones of several input optical fibers are arranged axially in sequence and then inserted into the inner sleeve, and the sleeve opening of the corrosion transition zone of the input optical fiber is made 8 to 12 mm.

[0014] Furthermore, during the first pipe knocking, the inner sleeve is clamped by the taper machine fixture, a cut is made on the inner sleeve by a cutting device, and then the inner sleeve is broken along the cut by lifting the taper machine lifting platform; the fracture is temporarily connected by a reversible adhesive.

[0015] Furthermore, during the second tapping, the inner sleeve is clamped by the taper machine fixture, and a cut is made on the inner sleeve by the cutting device; Use the lifting platform of the taper machine to break the inner casing along the cut; Removing the reversible adhesive allows the inner casing to be disconnected again from the fracture produced by the first knocking, thereby forming a free inner casing section; The free inner casing section is crushed by using a bench drill to form a knocking area.

[0016] Furthermore, during etching, the etching stripping efficiency is ≥30dB.

[0017] Beneficial effects: The root cause of high temperatures in the cone region is the breakdown of total internal reflection, which leads to concentrated leakage light, cladding light accumulation, and a high-temperature positive feedback loop. To reduce cladding light accumulation, the present invention exposes the cone in the knocked-out region, allowing the cladding light to escape in a dispersed manner, preventing it from concentrating and forming hot spots within the enclosed inner tube. The etched region blocks the cladding light's transmission path, reducing leakage power. This stepwise stripping of the cladding light reduces the leakage power caused by temperature rise and reduces additional leakage caused by changes in the quartz refractive index, effectively halting the vicious cycle of "rising temperature leads to more leakage" at its source.

[0018] The knock-tube region exposes the cladding light directly to the air, breaking the cladding's total internal reflection condition. The cladding light is no longer constrained in transmission, but is instead rapidly released through scattering. The air scattering in the knock-tube region, combined with the heat conduction of the alumina structural components, creates a dual channel for light scattering and heat conduction. The scattered cladding light dissipates heat through natural convection in the air and is conducted through the alumina structural components surrounding the knock-tube region to the water-cooled cooling plate.

[0019] Etching is performed on the straight section of the input fiber cone and the output fiber, achieving a stripping efficiency of ≥30dB. This further strips the residual cladding light uncovered in the knockout region, achieving a dual guarantee of primary stripping in the knockout region and secondary stripping in the etched region, significantly reducing the total cladding optical power. The alumina structural components are connected to a water-cooled plate via thermally conductive silicone gel, rapidly dissipating residual heat from the knockout and etched regions to prevent ambient temperature from feeding back into the cone region.

[0020] In the present invention, the inner tube is broken by "tapping," and the two tapping steps create a free segment, which is then broken up to create a tapping area for dissipating cladding light. The first tapping step is performed after taper drawing and before assembly of the outer tube, while the second tapping step is performed after etching and before packaging.

[0021] The purpose of knocking the tube is to break the inner tube to form a free segment, so that there is no force transmission between the inner tube and the input optical fiber, making it easier to break and the displacement smaller, and not easy to rotate or tear the optical fiber.

[0022] The first knockout occurs before the outer sleeve is installed. At this point, the input fiber is not yet glued and is relatively loose and difficult to break. Reversible glue is used to temporarily connect the broken part, without affecting the clamping fixture or subsequent cutting and splicing.

[0023] When knocking the tube for the second time, since the fracture of the first knocking is temporarily fixed by reversible glue, the entire inner sleeve can still withstand a large shear force and has sufficient rigidity when it is broken for the second time by the lifting platform, thereby avoiding the force being transmitted to the optical fiber and causing damage to the optical fiber.

[0024] The two-step tube knocking adopts a stepped design with the first preset notch to reduce stress and maintain clamping, and the second precise crushing to establish heat dissipation. This not only solves the problems of stress loss and structural damage in direct tube knocking, but also achieves multiple advantages of improved yield, reduced difficulty and stable performance through the reversibility of PEG-1500 and the controllable fragmentation length. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the embodiments or the description of the prior art. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the various elements or parts are not necessarily drawn according to the actual scale. Obviously, the drawings described below are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without inventive work.

[0026] Figure 1 This is a structural diagram of Example 1 of the present invention.

[0027] Figure 2 This is a flow chart of Example 2 of the present invention.

[0028] Figure 3 Schematic diagram of the primary pipe knocking and the secondary pipe knocking in Example 2 of the present invention.

[0029] Summary of reference numerals: 1-Input fiber, 2-Outer sleeve, 3-Inner sleeve, 4-Output fiber, 5-Fiber stripping end, 6-Etching area, 7-Fusion point, 8-Knocking area, 9-Glue point, 10-Blank area. DETAILED DESCRIPTION

[0030] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] Herein, suffixes such as "module," "component," or "unit" used to represent elements are only used to facilitate description of the present invention and have no specific meaning. Therefore, "module," "component," or "unit" may be used interchangeably.

[0032] As used herein, terms such as "upper," "lower," "inner," "outer," "front," "back," "one end," and "the other end" indicate positions or locations based on those shown in the accompanying drawings. These terms are intended solely to facilitate and simplify the description of the present invention and are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] As used herein, unless otherwise expressly specified or limited, the terms "installed," "provided with," and "connected" should be understood broadly. For example, "connected" may refer to a fixed connection, a detachable connection, or an integral connection; it may refer to a mechanical connection, a direct connection, an indirect connection via an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention on a case-by-case basis.

[0034] As used herein, "and / or" includes any and all combinations of one or more of the associated listed items.

[0035] Herein, "plurality" means two or more than two, ie, it includes two, three, four, five, etc.

[0036] Definition of noun: Signal combiner: A device that combines multiple input lasers into a single output fiber through fused-taper technology, with the core being cone mode coupling.

[0037] Fluorine-doped tube: Fluorine-doped quartz glass tube, used to constrain the optical fiber array and match the thermal expansion coefficient to prevent the taper from cracking.

[0038] Tapering: Stretching the optical fiber bundle under heating from a heat source to reduce the core diameter and increase the mode field, thereby achieving low-loss coupling of multiple optical signals.

[0039] PEG-1500: Polyethylene glycol (molecular weight 1500), melting point 44-48°C; used here as a thermoreversible temporary adhesive, it can bear force after curing and can be removed without damage after melting.

[0040] Cladding light: During fiber transmission, optical signals, which should be confined to the fiber's cladding but leak or escape from the original transmission path due to various reasons, such as waveguide damage or structural defects, can accumulate in key areas such as the combiner's taper, forming "cladding light accumulation." This buildup generates heat through optical-to-thermal conversion, contributing to high temperatures in the combiner's taper.

[0041] Etching stripping efficiency: cladding optical power attenuation (dB), ≥30dB means 99.9% of the light is stripped.

[0042] Mode mismatch: The core deformation (circular to elliptical) causes the difference in propagation constants between the fundamental mode and higher-order modes to increase, causing light leakage and heat accumulation.

[0043] Example 1 like Figure 1 As shown, this embodiment provides a signal combiner, comprising a plurality of input optical fibers 1 and an output optical fiber 4 fused to a cone formed by combining and tapering the plurality of input optical fibers 1; an inner sleeve 3 is provided on the outer surface of the input optical fiber 1, and the middle section of the inner sleeve 3 is removed after tapering to form a knock-tube area 8, so that the cone of the input optical fiber 1 inside the inner sleeve 3 is exposed; etched areas 6 are provided on both sides of the fusion point 7 between the output optical fiber 4 and the cone of the input optical fiber 1, so that the cladding light of the input optical fiber 1 can be scattered through the knock-tube area 8 and the etched area 6.

[0044] In this embodiment, input fiber 1 is a multi-channel parallel optical fiber used to carry multiple initial laser signals. Output fiber 4 is a single optical fiber. It is fused to the input fiber 1 through a tapered cone, achieving the converged output of multiple optical signals. The fusion of the two must meet the cutting angle of ≤1° to ensure symmetry and reduce the risk of optical damage.

[0045] The cone formed by combining and tapering the input fiber 1 is the core region for optical signal coupling. During the tapering process, the fiber is stretched by a heat source, reducing the core diameter and expanding the mode field, enabling mode coupling of multiple optical signals from the input fiber 1 to the output fiber 4. However, tapering can also cause core distortion, such as from a circular shape to an elliptical shape, leading to mode mismatch and cladding light leakage.

[0046] The inner sleeve 3, specifically a fluorine-doped quartz glass tube, is placed over the input fiber 1. Its core function is to constrain the relative position of the input fiber 1 array before tapering, preventing misalignment during heating and stretching. It also matches the thermal expansion coefficient of the input fiber 1, ensuring stability during the tapering process.

[0047] After the inner tube 3 is tapered, the middle section is removed to form a knockout region 8, exposing the tapered portion of the input optical fiber 1 within. The purpose of knocking out the inner tube 3 is to break the confinement of the input optical fiber 1's tapered portion, allowing the exposed tapered portion to come into direct contact with the air. This allows the cladding light to be scattered by the air medium and prevents the cladding light from accumulating and generating heat within the enclosed space.

[0048] Etched regions 6 are located on either side of the splice 7 between the output fiber 4 and the input fiber 1. Etching must achieve an isolation of 30 dB or higher, meaning it strips away at least 99.9% of the cladding light. This process further removes any residual cladding light that is not scattered by the knockout region 8. The two sides of the splice 7 are areas where cladding light is prone to accumulation (light leakage from the straight section of the cone due to tapering distortion, and additional light leakage from the output fiber 4 due to splice stress). Etching physically disrupts the cladding's waveguide structure, forcing the cladding light to scatter there, preventing it from propagating toward the combiner's core.

[0049] The root cause of high temperatures in the cone region is the breakdown of total internal reflection, which leads to concentrated leakage light, cladding light accumulation, and a high-temperature positive feedback loop. To reduce cladding light accumulation, this embodiment exposes the cone by knocking out the tube 8, allowing the cladding light to escape in a dispersed manner, preventing it from concentrating and forming hot spots within the enclosed inner tube 3. The etched area 6 blocks the cladding light's transmission path, reducing leakage power. This stepwise stripping of the cladding light reduces the leakage power caused by temperature rise and reduces additional leakage caused by changes in the quartz refractive index, effectively stopping the vicious cycle of "rising temperature leads to more leakage" at its source.

[0050] Compared to the prior art, which uses high-refractive-index polymer cladding optical stripping and active cooling with a water-cooled sleeve, this embodiment achieves cladding optical stripping through mechanical knocking to remove the inner sleeve 3 and physical etching, eliminating the need for expensive materials or complex cooling systems, effectively reducing costs. The inner sleeve 3, which constrains the fiber and prevents cracking during the tapering stage, is removed by knocking after the tapering is complete, preserving its process necessity while avoiding heat dissipation. The high isolation of the etched area 6 ensures efficient cladding optical stripping and reduces the risk of thermal damage during long-term use.

[0051] Specifically, in this embodiment, the etched region 6 on the input optical fiber 1 is adjacent to the fusion splice 7; a blank region 10 is provided directly between the etched region 6 and the fusion splice 7 on the output optical fiber 4. The straight tapered section of the input optical fiber 1 is fully etched to form the etched region 6; the etched region 6 on the output optical fiber 4 is 9-11 mm long, and the blank region 10 is 6-8 mm long.

[0052] The cone of the input fiber 1 is the core area of ​​the tapering process, where core distortion and cladding thermal damage are concentrated, leading to significant cladding light leakage. The fully etched design physically destroys the cladding waveguide structure of the straight section of the cone, forcing the cladding light to scatter here and preventing the cladding light from accumulating in the core area of ​​the cone and forming high temperatures. The fusion point 7 between the cone and the output fiber 4 is the turning point for optical signal coupling, where cladding light is susceptible to secondary leakage due to mode mutation. The etched area 6, adjacent to the fusion point 7, can quickly strip away the leaking light near the fusion point 7, blocking the cladding light's transmission path to the output fiber 4 and preventing further accumulation of leaked light in the output fiber 4.

[0053] The setting of the 6~8mm blank area 10 on the output optical fiber 4 can prevent the etching process from directly acting on the fusion point 7, avoid mechanical damage or refractive index disturbance of the fusion interface caused by etching, and ensure the optical coupling efficiency. If the blank area 10 is too short, the etching may affect the fusion point 7, and if it is too long, the cladding light near the fusion point 7 cannot be stripped off in time, forming local heat accumulation. The etching length of the output optical fiber 4 is 9~11mm, which ensures sufficient etching area to meet the requirements of cladding light scattering. The function of the inner sleeve 3 is to constrain the optical fiber array and match the thermal expansion coefficient to prevent the cone from cracking. However, objectively, the inner sleeve 3 hinders the heat dissipation of the cladding light. The knocking area 8 on the inner sleeve 3 is an exposed area formed by removing part of the inner sleeve 3 through the knocking process. The purpose is to expose the cone part of the internal input optical fiber 1 so that the cladding light is evenly scattered through the air medium. More specifically, the ratio of the knock tube region 8 to the overall length of the inner sleeve 3 is 1:15 to 1:5. That is, when the inner sleeve 3 is 15 cm long, the knock tube region 8 is 1 to 3 cm long, thus achieving a balance between cladding light scattering efficiency and the ability to constrain the input optical fiber 1. If the knock tube region 8 is too short, the cladding light scattering will be insufficient, failing to address the high-temperature issue. If it is too long, the remaining portion of the inner sleeve 3 will have difficulty constraining the optical fiber, resulting in structural instability and exacerbating light leakage.

[0054] In addition, the signal combiner in this embodiment further includes an outer sleeve 2 sleeved on the tail end of the input optical fiber 1, and the outer sleeve 2 partially overlaps with the inner sleeve 3; the two ends of the outer sleeve 2 are respectively bonded and fixed to the input optical fiber 1 and the inner sleeve 3 using glue.

[0055] The tail end of input fiber 1 is the starting point for optical signal input and must withstand the stress of insertion and removal during external connections (such as light source coupling). The outer sleeve 2 is placed over the tail end and partially overlaps with the inner sleeve 3, forming a double-layer protective structure. This enhances the fiber's bending resistance and protects the fiber coating from external forces.

[0056] The glue bonding method can disperse stress and prevent stress concentration from causing optical fiber breakage. Its performance needs to reach a fiber deviation of <0.5μm under the thermal cycle life test (-40℃~150℃, 1000 cycles). The protection of the outer sleeve 2 can ensure that the tail end remains stable when the temperature changes.

[0057] Contaminants can disrupt total reflection and exacerbate cladding light leakage. The overlapping area between the outer sleeve 2 and the inner sleeve 3 is sealed with glue to prevent contaminants such as dust and moisture from entering the gap between the optical fiber and the inner sleeve 3, forming an integrated dustproof and heat-dissipating structure.

[0058] Glue is applied at the junction of the outer sleeve 2 and the coating of the input fiber 1. The glue seeps into the gap between the outer sleeve 2 and the fiber, forming a sleeve-glue-fiber sandwich structure, enhancing tensile strength and preventing the fiber from being pulled out. Glue is applied at the overlap between the outer sleeve 2 and the inner sleeve 3, filling the entire gap to ensure a rigid connection. The glue's high refractive index and high bond strength achieve dual functions of mechanical protection and optical control.

[0059] It is worth noting that although the overlapping area of ​​the outer sleeve 2 and the inner sleeve 3 is fixed with glue, the knockout area 8 is located in the middle section of the inner sleeve 3 rather than the overlapping area, ensuring that the cladding light can be scattered into the air through the knockout area 8.

[0060] In addition, some embodiments further include an alumina structure for encapsulating the signal combiner. A sapphire glass recess for accommodating the signal combiner and a glass cover for sealing the signal combiner are fixed within the alumina structure. Heat is dissipated from the alumina structure via a water-cooled plate.

[0061] Alumina, with its high hardness and high temperature resistance, stabilizes the overall structure of the combiner, preventing the input / output optical fibers 4 from shifting due to external forces. Its electrical insulation properties also prevent potential electrostatic interference in laser components, ensuring stable optical transmission. Sapphire, with its excellent light transmittance and stable refractive index, allows the combiner to be placed in a sapphire groove, securing the optical fibers through the groove's geometric constraints while preventing interference with cladding light scattering in the knock-tube region 8. The glass cover seals the interior of the alumina structure, preventing dust and moisture from entering the knock-tube region 8 or the etched area 6, thereby preventing contaminants from adhering to the exposed optical fiber surfaces and causing additional light leakage.

[0062] The water-cooled plate is an active heat dissipation actuator. Heat generated by cladding light scattering must be continuously dissipated through the water-cooling system. The cooling medium (such as water or ethylene glycol solution) flowing through the water-cooled plate quickly removes heat transferred from the alumina components, preventing heat accumulation in the core area of ​​the combiner.

[0063] Example 2 This embodiment also provides a signal combiner preparation method for preparing the above-mentioned signal combiner. Taking the preparation process of a standard 7*1 signal combiner as an example, the steps specifically include: S1 tapers, inserting several input optical fibers 1 into the inner sleeve 3, heating and stretching the inner sleeve 3 and the input optical fibers 1 to form a cone on the input optical fibers 1, and removing the end of the cone that is not connected to the input optical fibers 1.

[0064] Tapering is the core process for signal combiners to achieve low-loss coupling of multiple optical signals. Essentially, it forms a tapered structure within the inner tube 3 (the fluorine-doped tube used in this embodiment) by heating and stretching the optical fiber array. Before tapering, seven etched optical fibers with an etched diameter of x microns are threaded into a fluorine-doped tube with a reserved inner diameter of 3x + 5 microns. Etched optical fibers are fibers whose diameter has been reduced by chemical etching in specific areas. The etched diameter refers to the diameter of the etched optical fibers after this reduction.

[0065] Before threading, the seven input optical fibers (1) were arranged axially in sequence, ensuring minimal overlap and blocking of the transition zones. This prevents interference between the refracted light. The transition zone of a corroded optical fiber is the area where the diameter gradually changes from the coating to the corroded surface, and is a sensitive area for initial cladding light leakage. If the transition zones overlap, the refracted light will interfere with each other, resulting in localized strong light and exacerbating cladding light accumulation. However, an orderly arrangement ensures uniform scattering of the refracted light, reducing localized heat accumulation.

[0066] To make threading easier, alcohol can be used to assist. Alcohol acts as a lubricant, reducing friction between the optical fibers and the inner wall of the fluorine-doped tubing, ensuring that the seven fibers are aligned as planned and avoiding misalignment and uneven tapering. Alcohol also dissolves contaminants on the fiber surface, preventing contamination at the tubing interface.

[0067] In addition, before tapering, it is necessary to use a vacuum tool and a hot air blower to remove any residual alcohol. Tapering requires high temperatures, and if residual alcohol evaporates due to the heat, it can form bubbles between the fiber and the fluorine-doped tubing. These bubbles can cause localized uneven temperature distribution and lead to thermal damage to the fiber cladding.

[0068] When threading the tube, it should be noted that the end of the fluorine-doped tube should be away from the optical fiber stripping end 5, and the transition zone of the corroded optical fiber should be kept 8 to 12 mm away from the end of the fluorine-doped tube to facilitate the subsequent tapering work.

[0069] After completing the above preparations, a taper welding machine model GPX-3850 is used to perform taper forming. The specific process is existing technology and will not be described in detail here.

[0070] After the cone is drawn, the cone is cut on a machine, and the end without the input optical fiber 1 is discarded, leaving only the input optical fiber 1, the inner sleeve 3 and the cone at the head end of the input optical fiber 1.

[0071] S2 knocks the pipe once, breaks the inner sleeve 3 and makes a temporary connection at the fracture.

[0072] After the taper is complete, continue to maintain the taper machine fixture's grip on inner ferrule 3. Shift the input fiber 1 and inner ferrule 3 as a whole, ensuring the fixture simultaneously grips both the inner ferrule 3 and the coatings of the seven optical fibers, preventing any shaking. The fixture opening should be positioned close to the fiber's corrosion transition zone to minimize the overhang in this transition zone.

[0073] like Figure 2 As shown, a cutting device such as a cutting pen is used to cut a notch on the inner sleeve 3. The notch should surround the entire circumference of the inner sleeve 3 so that the fracture is neat. Then, the inner sleeve 3 is broken along the notch by using the lifting platform of the taper machine. Specifically, the lifting platform is raised to the bottom of the inner sleeve 3, slowly lowered to the notch (offset from the notch), and then slowly raised to break the inner sleeve 3 along the circumference of the notch. The parallel distance between the edge of the lifting platform and the scratch is about 0.5mm-0.7mm, ensuring that the squeezing force of the lifting platform on the inner sleeve 3 is concentrated at the scratch, causing the fracture to occur along the scratch, thereby making the fracture neat and convenient for subsequent bonding. After the lifting platform is reset, the broken part of the inner sleeve 3 also returns to its original position and is aligned with the remaining part of the inner sleeve 3.

[0074] Heat and melt solid PEG-1500 and apply it to the fracture of the inner sleeve. After curing, ensure that the internal cone does not collapse. Then, reapply PEG-1500 to the fracture, leaving it suspended. PEG-1500 (polyethylene glycol, molecular weight 1500) is a thermoreversible material (melting point 44-48°C). After curing, it provides sufficient lateral bearing capacity for temporary fixation. It can be removed by heating and melting for subsequent secondary tapping.

[0075] It's important to control the amount of PEG-1500 used during the process to prevent it from seeping through the fracture into the gap between the inner sleeve 3 and the optical fiber. This can cause fiber adhesion and subsequent difficulty in removal. Furthermore, the fractures should be completely aligned, and the glue should be applied in small, repeated applications to ensure complete curing and sufficient lateral bearing capacity. Repeated re-applications ensure that the gap at the defect is fully filled, forming a single, load-bearing structure after curing, preventing the cone from collapsing due to gravity.

[0076] Of course, other reversible adhesives such as paraffin / microcrystalline wax mixtures and low molecular weight PVP aqueous solutions can also be used, but compared to PEG-1500, they each have their own disadvantages: the paraffin / microcrystalline wax mixture has low viscosity, and the residue after adding the thickener is difficult to remove, which will contaminate the optical fiber; the low molecular weight PVP aqueous solution has poor temperature resistance and is prone to cracking at high temperatures.

[0077] S3 assembles the outer sleeve 2, puts the outer sleeve 2 on the tail end of the input optical fiber 1, and inserts the inner sleeve 3 partially into the outer sleeve 2; uses glue to bond and fix the two ends of the outer sleeve 2 to the input optical fiber 1 and the inner sleeve 3 respectively.

[0078] The purpose of providing the outer sleeve 2 is to physically protect the bare fiber area (fiber stripping end 5 and fluorine-doped tube end) through the glass protective tube, and to fix it with high-refractive glue to avoid mechanical damage.

[0079] A glass protective tube with an outer diameter larger than that of the inner tube by 3100 microns is selected as the outer tube 2, which is inserted from the tail end of the input optical fiber 1. The inner tube 3 is partially inserted into the outer tube 2 so that the two partially overlap to facilitate bonding.

[0080] Set glue points 9 at about 7 mm from the fiber stripping end 5 of the input optical fiber 1 and at about 7 mm from the end 3 of the inner sleeve, apply glue and cure with ultraviolet light.

[0081] The glue used to secure the outer tube 2 is a transparent, high-refractive index glue with a coefficient of thermal expansion close to that of the glass. The glue is inserted into the tube approximately 3 mm. The choice of a high-refractive index glue (with a higher refractive index than the fiber cladding) reduces light reflection at the interface between the protective tube and the fiber. Its transparency ensures that it does not obstruct subsequent cladding light scattering in the knocking area 8 and the etching area 6. The glue's coefficient of thermal expansion matches that of the inner and outer glass tubes 2, preventing cracking of the glue or loosening of the protective tube due to temperature fluctuations.

[0082] S4 etching: after the input optical fiber 1 cone and the output optical fiber 4 are fused, etching is performed on the straight section of the input optical fiber 1 cone and the output optical fiber 4 to form an etched area 6.

[0083] The purpose of etching is to selectively remove the cladding of the tapered straight section and a specific area of ​​the output optical fiber 4, so that the cladding light is exposed to the air and directly scattered.

[0084] First, fuse the input fiber 1 with the protective tube to the auxiliary fiber (used to assist in flattening the cone). After flattening the cone end, fuse the flattened output fiber 4. During the splicing process, ensure that the axial alignment accuracy of the cone and the output fiber 4 is ≤1μm.

[0085] After fusion splicing with the output fiber 4, the combiner prototype is placed on a suspended structure, secured with high-temperature tape, and transferred to the etching machine. During etching, the stripping efficiency of the etcher is set to ≥30dB. Etching is performed on the straight section of the cone and the output fiber 4, 76-8mm from the splice point, with a 9-11mm etching distance on the output fiber 4. Etching efficiency must ensure that the cladding light power density is reduced to less than 1 / 1000 of its initial value. A stripping efficiency of 30dB means that 99.9% of the cladding light is removed, significantly reducing cladding light accumulation during subsequent transmission. The straight section of the cone is the primary area for cladding light leakage, and the cladding structure is destroyed during the tapering process. Full etching maximizes cladding light exposure. The 76-8mm distance from the splice point avoids the splice hotspot and prevents corrosion in the splice area. The 9-11mm etching length disperses any cladding light that may remain in the output fiber 4.

[0086] S5 is a secondary pipe knocking step, which breaks the inner casing 3 a second time to form a new fracture and disconnects the temporary connection during the first pipe knocking step; and then the free inner casing 3 segments formed by the second break are crushed to form a pipe knocking area 8.

[0087] The purpose of secondary knocking is to form a knocking area 8 of a specific length by controllably breaking part of the inner casing 3, exposing the cone to the air and taking advantage of the high heat dissipation coefficient of the air to directly remove the heat generated by the cladding light scattering. Figure 2 As shown, the specific steps include: S51 clamps the inner sleeve 3 by a taper machine fixture, and cuts a cut on the inner sleeve 3 by a cutting device.

[0088] Place the etched beam combiner on the taper welding machine and use a fixture to hold the inner sleeve 3, leaving it partially suspended. The length of the suspension depends on the length of the knocking area 8. For example, if the knocking area 8 is 1 cm long, the suspension distance between the first knocking fracture and the fixture should be at least 1 cm.

[0089] Similar to the primary knocking procedure, use a cutting device, such as a cutting pen, to create a cut in the inner sleeve 3. The cut should circumscribe the entire circumference of the inner sleeve 3, ensuring a clean break. The location of the cut is determined by the length of the knocking zone 8. The distance between the cut and the break in the primary knocking is the length of the knocking zone 8.

[0090] S52 utilizes the lifting platform of the taper machine to break the inner sleeve 3 along the cut.

[0091] The lifting platform is raised to the bottom of the inner sleeve 3, slowly lowered to the secondary cut (staggered with the cut) and then slowly raised to break the inner sleeve 3 along the circumference of the secondary cut.

[0092] S53 removes the reversible adhesive so that the inner casing 3 is disconnected again from the fracture produced by the first knocking, thereby forming a free inner casing 3 section.

[0093] Use a heating device to melt the PEG-1500 at the fracture of the first tap, then clean it with a cotton swab dipped in alcohol. After cleaning, the fracture caused by the first tap re-breaks, now forming two fractures on the inner sleeve 3, and the section of inner sleeve 3 between the two fractures is free and needs to be removed.

[0094] In step S54 , the three sections of the free inner casing are crushed by using a bench drill, thereby forming a knocking area 8 .

[0095] In this embodiment, a bench drill with adjustable height is used to crush the three sections of the free inner casing. First, the bench drill is placed on a lifting platform and double-sided tape is attached to the bottom of the bench drill as a cushion layer.

[0096] Adjust the position of the lift platform so that the drill bit's base rests against the bottom of the inner cannula 3. Ensure that no force is applied to the input optical fiber 1 inside the inner cannula 3 during this process. Once the base makes contact with the bottom of the inner cannula 3, rotate the drill bit vertically from top to bottom until it contacts the free inner cannula 3 segment. Gently rotate the drill bit to compress the outer wall of the free inner cannula 3 segment, causing it to break apart. Repeat this process until the entire free inner cannula 3 segment is broken apart. Use a cell clamp to remove any debris during this process.

[0097] After the crushing is completed, the area between the two remaining inner casings 3 is the knocking area 8.

[0098] S6 packaging, the signal combiner is fixed in a sapphire glass groove in an alumina structure, and a water cooling plate is used for heat dissipation.

[0099] The purpose of packaging is to achieve the integration of mechanical fixation, environmental protection and efficient heat dissipation of the combiner through the coordination of components such as alumina structural parts, sapphire glass grooves, and glass cover plates, ensuring that the device maintains stable optical performance and thermal environment during long-term operation.

[0100] The alumina structural component has a thermal conductivity of ≥20W / (m・K). As a heat dissipation carrier, it can quickly transfer the heat scattered by the knock tube area 8 and the etching area 6 to the water cooling plate. At the same time, its high mechanical strength (Mohs hardness 9) and high temperature resistance (melting point 2054℃) can provide rigid support for the combiner and prevent fiber deviation caused by external forces.

[0101] Sapphire has excellent light transmittance and strong chemical stability. The gap between the sapphire groove and the signal combiner is ≤0.1mm, which can accurately fix the combiner body and prevent micro-displacement of the optical fiber due to vibration or temperature changes, while not obstructing the cladding light scattering path.

[0102] The cleanliness of the components before packaging must be ≥ Class 100 to prevent contaminants from adhering to the knockout area 8, which could obstruct cladding light scattering or cause localized hot spots due to poor thermal conductivity. After cleaning, gently place the combiner inside the alumina component and secure it with high-yield glue on both sides and low-yield glue near the knockout area 8.

[0103] The signal combiner is fixed at both ends with a high refractive index glue of ≥1.5. The thermal expansion coefficient of the glue matches that of alumina, with a deviation of ≤5×10⁻ 6 / ℃. The high refractive index of the high-refractive index glue is higher than that of the optical fiber cladding, which can reflect the edge leakage light back to the fiber core or absorb it, reducing the interference of stray light. At the same time, its high hardness after curing can withstand the stress caused by thermal cycling and prevent the overall displacement of the combiner. The knock tube area 8 is the core area of ​​cladding light scattering. The selection of low-refractive index glue (transmittance ≥ 90%) can avoid the glue's reflection or absorption of the cladding light, ensuring that the cladding light is efficiently scattered through the air-low-refractive index glue interface, and the thermal conductivity of alumina is used to conduct heat away.

[0104] After gluing, a glass cover is attached to prevent dust, and finally, the alumina structural cover is added to achieve integrated heat dissipation. After packaging, internal dust particles are ≤10 particles / μm³. Dust adhering to the knockout area 8 or the etched area 6 disrupts the air scattering path, leading to heat accumulation. The glass cover has excellent light transmittance and isolates external contaminants, ensuring long-term heat dissipation efficiency.

[0105] The upper cover plate of the alumina structural component and the lower base plate (including the water-cooling plate interface) form a closed heat dissipation channel. The heat in the knocking tube area 8 is quickly discharged through the alumina structural component → thermal conductive silicone gel → water-cooling plate, realizing a closed loop of light scattering-heat conduction-active cooling.

[0106] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0107] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A signal combiner, characterized in that: The invention comprises a plurality of input optical fibers and an output optical fiber fused to a cone formed by merging and tapering the plurality of input optical fibers; the input optical fibers are covered with an inner sleeve, and the middle section of the inner sleeve is removed after tapering to form a knock-tube area, so that the input optical fiber cone inside the inner sleeve is partially exposed; and etched areas are provided on both sides of the fusion point between the output optical fiber and the input optical fiber cone, so that the cladding light of the input optical fiber can be scattered through the knock-tube area and the etched area.

2. The signal combiner according to claim 1, characterized in that: The etched area on the input optical fiber is adjacent to the fusion point; a blank area is directly provided between the etched area and the fusion point on the output optical fiber; the straight section of the input optical fiber cone is fully etched to form the etched area; the length of the etched area on the output optical fiber is 9~11mm, and the length of the blank area is 6~8mm.

3. The signal combiner according to claim 1, wherein: The ratio of the inner casing knocking area to the overall length of the inner casing is 1:15 to 1:

5.

4. The signal combiner according to claim 1, wherein: It also includes an outer sleeve sleeved on the tail end of the input optical fiber, wherein the outer sleeve partially overlaps with the inner sleeve; the two ends of the outer sleeve are respectively bonded and fixed to the input optical fiber and the inner sleeve by glue.

5. The signal combiner according to claim 1, characterized in that: It also includes an alumina structural member for encapsulating the signal combiner; a sapphire glass groove for placing the signal combiner and a glass cover for sealing the signal combiner are fixed in the alumina structural member; the alumina structural member dissipates heat through a water cooling plate.

6. A method for preparing a signal combiner, for preparing the signal combiner according to any one of claims 1 to 5, characterized in that include: Tapering: inserting several input optical fibers into an inner sleeve, heating and stretching the inner sleeve and the input optical fibers to form a cone on the input optical fibers, and removing the end of the cone that is not connected to the input optical fibers; Knock the pipe once, break the inner casing and make a temporary connection at the fracture; Assemble the outer sleeve, put the outer sleeve on the tail end of the input optical fiber, and make sure that the inner sleeve is partially inserted into the outer sleeve; Use glue to bond and fix the two ends of the outer sleeve to the input optical fiber and the inner sleeve respectively; Etching: After the input fiber cone and the output fiber are fused together, etching is performed on the straight section of the input fiber cone and the output fiber to form an etched area; Secondary knocking: the inner tube is broken a second time to form a new fracture, and the temporary connection during the first knocking is disconnected; the free inner tube section formed by the second break is then crushed to form a knocking area to obtain the semi-finished signal combiner; The semi-finished signal combiner is packaged and fixed in a sapphire glass groove in an alumina structural component, and a water cooling plate is used for heat dissipation.

7. The method for preparing a signal combiner according to claim 6, wherein: When taper drawing, the corrosion transition zones of several input optical fibers are arranged axially in sequence and then inserted into the inner sleeve, and the sleeve opening of the corrosion transition zone of the input optical fiber is made 8 to 12 mm.

8. The method for preparing a signal combiner according to claim 6, wherein: During the first tapping, the inner sleeve is clamped by the taper machine fixture, a cut is made on the inner sleeve using a cutting device, and then the inner sleeve is broken along the cut by lifting the taper machine lifting platform; a temporary connection is made at the fracture end using a reversible adhesive.

9. The method for preparing a signal combiner according to claim 8, wherein: During the second tapping, the inner casing is clamped by the taper machine fixture, and the cutting equipment is used to cut the inner casing; Use the lifting platform of the taper machine to break the inner casing along the cut; Removing the reversible adhesive allows the inner casing to be disconnected again from the fracture produced by the first knocking, thereby forming a free inner casing section; The free inner casing section is crushed by using a bench drill to form a knocking area.

10. The method for preparing a signal combiner according to claim 6, wherein: During etching, the etching stripping efficiency is ≥30dB.

Images