A return light processing device and its preparation method

Abstract

This invention discloses a return light processing device and its fabrication method. The device includes a cladding stripper, an optical fiber placement slot structure, and a return light monitoring module. The input-side optical fiber of the cladding stripper is coiled and fixed, and the output pigtail of the cladding stripper is fabricated with a spherical end face to regulate the return light transmission path and suppress end face reflection. The optical fiber placement slot structure has several optical fiber placement slots, and the pigtail is fixed within these slots. The return light monitoring module is located in the optical path and is used to collect the return light signal, and adjust the optical power and / or protect the laser based on the collected return light signal. This invention is compact, easy to manufacture and maintain, low in cost, and safe and reliable.

Description

Technical Field

[0001] This invention belongs to the field of laser return light processing technology, and particularly relates to a return light processing device and its preparation method. Background Technology

[0002] During transmission, high-power lasers generate backlight due to Fresnel reflection at the fiber end face, reflection at optical device interfaces, and high backscattering from the workpiece. When the power of the backlight exceeds a certain threshold, it enters the laser resonant cavity and gain fiber, causing output power fluctuations and beam quality deterioration. In severe cases, it can instantly burn out active components such as the pump source, gain fiber, and cladding stripper, resulting in permanent damage to the laser and even safety accidents. Therefore, an efficient and reliable backlight handling solution is a core prerequisite for ensuring the long-term stable operation of high-power fiber lasers.

[0003] Currently, existing return light processing solutions, such as Figure 1 As shown, its structure consists of a cladding light stripper 2 and a fiber optic patch cord splice 3, with the fiber optic patch cord 4 inserted into the receiver box 5 and locked in place. The returned light is absorbed by the light-absorbing material in the receiver box 5. While this scheme can achieve some dissipation of the returned light, it suffers from the following insurmountable drawbacks in practical applications: First, low space utilization restricts the modular design of the laser. The receiver box has significant vertical dimensional redundancy, leading to an increase in the overall height of the laser and a substantial reduction in the utilization of three-dimensional space, severely hindering the development of high-power fiber lasers towards miniaturization, compactness, and modularity. Second, poor maintainability and low production efficiency. Receiver boxes often adopt a compact stacked installation structure, severely limiting the operating space for operators when installing or removing fiber optic patch cords. Often, the entire receiver box needs to be disassembled to complete the operation, significantly increasing the time spent on production assembly and subsequent maintenance, and reducing production efficiency. Third, high material and labor costs. This solution requires additional fiber optic patch cords and receiver boxes, and the cladding stripper needs to be fused and fixed to the fiber optic patch cords, which increases the material procurement cost and the labor cost of system assembly.

[0004] To address the return loss problem caused by reflection at the fiber end face, existing technologies disclose a fiber end spherical treatment technique. For example, Chinese patent CN101165516A discloses an optical fiber coupler and its fiber end treatment method, which melts the unwanted fiber end of the optical fiber coupler using a discharge instrument to form a spherical structure. The sphere is used to dissipate light after multiple reflections and refractions within the cladding, thereby avoiding the unstable return loss problem caused by UV adhesive aging and stabilizing the return loss at over 60dB.

[0005] However, the aforementioned technologies are only applicable to low-power fiber optic communication at the milliwatt level, addressing the end-of-line processing of excess pigtails in fiber optic couplers and solving the problem of return loss fluctuations affecting transmission quality in communication systems. They cannot be directly applied to return light processing in kilowatt / ten-kilowatt high-power fiber lasers. Furthermore, they lack active safety protection mechanisms, only achieving passive return light dissipation, and lack any return light power monitoring or automatic protection devices. This makes them unable to cope with sudden, strong return light failures, posing serious safety hazards. Summary of the Invention

[0006] The purpose of this invention is to provide a return light processing device and preparation method, which partially solves or alleviates the above-mentioned shortcomings in the prior art. It has a compact structure, is easy to produce and maintain, has low cost, and is safe and reliable.

[0007] To solve the aforementioned technical problems, the present invention specifically adopts the following technical solution: A first aspect of the present invention is to provide a return light processing apparatus, comprising a cladding light stripper, an optical fiber placement slot structure, and a return light monitoring module; The input fiber coil of the cladding stripper is fixed, and the output pigtail of the cladding stripper is prepared with a spherical end face to regulate the return light transmission path and suppress end face reflection; the fiber placement slot structure is provided with several fiber placement slots, and the pigtail is fixed in the fiber placement slots; the return light monitoring module is located in the optical path to collect the return light signal and adjust the optical power and / or protect the laser based on the collected return light signal.

[0008] Furthermore, the backlight monitoring module includes a photodetector, a transimpedance amplifier, an analog-to-digital converter, and a microcontroller unit connected in sequence; the photodetector is used to collect the backlight signal, and the output terminal of the microcontroller unit is connected to the resistance control terminal of the transimpedance amplifier and the drive control terminal of the laser, respectively, for adjusting the resistance of the transimpedance amplifier and performing laser protection actions; The microcontroller unit is configured to: Acquire the return optical signal fed back by the photodetector; When the returned optical power is higher than the preset strong signal threshold, the formula f=f r -k1 adjusts the resistance of the transimpedance amplifier; when the returned optical power is lower than the preset weak signal threshold, the formula f=f r +k2 adjusts the transimpedance amplifier's resistance value; where f is the adjusted transimpedance amplifier's resistance value, fr is the current transimpedance amplifier's resistance value, k1 is the transimpedance amplifier's adjustment step under a strong signal, and k2 is the transimpedance amplifier's adjustment step under a weak signal. When the real-time acquired return optical power exceeds the safety threshold, a control signal is sent to the laser driver module to perform a protection action by reducing the drive current or directly shutting down the laser.

[0009] Furthermore, the optical fiber placement slot structure is pre-set with a spare optical fiber placement slot.

[0010] Furthermore, the optical fiber placement slot is filled with a photocurable adhesive with a refractive index of 1.48~1.54 for fixing the pigtail.

[0011] Furthermore, the optical fiber of the spherical end face section is suspended; it also includes a pressure block, which is located on the top of the optical fiber placement slot structure and is used to seal and isolate the end face of the suspended optical fiber section for protection.

[0012] Furthermore, the distance between the suspended optical fiber of the spherical end face section and the bottom of the optical fiber placement slot structure is not less than 50mm.

[0013] The present invention also provides a method for preparing a return light processing device, which is used to prepare the above-mentioned return light processing device, comprising: After the input fiber of the cladding stripper is coiled and fixed, the output pigtail of the preset length is measured and the end face of the output pigtail is cut to obtain a flat and vertical fiber end face. The cut fiber end face is subjected to gradient melting treatment to form a spherical end face with a uniform radius of curvature at the end of the fiber. The transmission path of the returning light is controlled by the spherical end face, and the back reflection of the end face is suppressed. The pigtail that has undergone the sintering process is placed in the slot of the fiber placement groove structure. The pigtail is fixed and the fiber placement groove is filled with a photocurable adhesive. The fiber of the spherical end face section is suspended.

[0014] Furthermore, the end face cutting is performed using an optical fiber cutting device with cutting parameters of cutting speed 290~310 bits, tension speed 18~22 bits, cutting tension 560~600 bits, and the reserved length of the optical fiber after cutting is 5mm-7mm.

[0015] Furthermore, the gradient melting process sequentially includes three stages: cleaning discharge, pre-melting, and main discharge. The parameters for the clean discharge phase are: discharge power 380~400 bits, discharge time 145~155 ms; The discharge power during the pre-melting stage is 380~400 bits; The discharge power of the main discharge stage is 380~400 bits, and the discharge time is 5950~6050 ms.

[0016] Furthermore, the photocurable adhesive has a refractive index of 1.48-1.54 and is cured using ultraviolet light with a wavelength of 220-260nm.

[0017] Beneficial effects: This invention completely eliminates the need for fiber optic patch cords and receiver boxes required by traditional solutions, directly implementing return light processing at the tail end of the cladding stripper, achieving a return light processing architecture without patch cords or receiver boxes. The vertical height of the return light processing module is reduced by approximately 10mm, eliminating the vertical dimensional redundancy of the receiver box, significantly improving the three-dimensional space utilization of the laser, and providing key support for the miniaturization, modularization, and compact design of high-power lasers.

[0018] By eliminating the two steps of cladding stripper and fiber optic patch cord splicing and receiver box installation, the processing time for a single batch of return light is shortened, significantly reducing the production cycle. The elimination of all supporting materials such as fiber optic patch cords, receiver box housings, light-absorbing materials, and connectors reduces the material cost of the return light processing module. The reduction of complex manual operations such as splicing, patch cord assembly, and receiver box debugging lowers the skill requirements for operators, further reducing production time costs.

[0019] This invention allows for maintenance without disassembling any core components, solving the problems of limited space for patch cord installation and removal caused by stacked optical receiver boxes in traditional solutions, which require complete disassembly of the optical receiver box. The fiber placement slot structure has a pre-set dedicated repair slot. When the spherical end face is damaged, it is only necessary to recut the burnt-ball pigtail and fix it to the spare slot, without replacing the entire return optical processing module, thus shortening the repair time.

[0020] This invention establishes and utilizes a dynamic adaptation relationship between the returned optical power PD monitoring signal and the transimpedance amplifier (TIA) resistance value to resolve the contradiction between monitoring range and accuracy caused by traditional fixed resistance designs. Specifically, this innovation proposes dynamically adjusting the feedback resistance value by monitoring the TIA output voltage in real time or predicting the operating state. For example, the resistance value is automatically reduced to prevent saturation when the signal is strong, and automatically increased to improve accuracy when the signal is weak. This ensures the monitoring system always operates within its optimal linear range. This not only effectively expands the dynamic range of optical power monitoring and significantly improves monitoring accuracy and the module's environmental adaptability, but also upgrades the TIA from a fixed component to a key intelligently configurable component, achieving optimized and intelligent management of optical module monitoring performance.

[0021] This invention constructs a highly efficient and reliable laser safety defense by setting and comparing the feedback signal of the monitored power digitizer (PD) with a preset upper limit threshold in real time. Its core achievement lies in realizing a shift from passively accepting risks to proactive intelligent protection: once the detected optical power exceeds the safety threshold, the system can immediately take protective actions such as reducing the laser drive current or directly shutting it down, thereby effectively preventing permanent damage to the laser caused by sudden spikes in optical power due to overload, aging, or external disturbances. This not only significantly improves the long-term reliability of the laser but also reduces maintenance costs caused by the failure of the core light source, ensuring the entire optical module operates in a safe and stable state. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. The elements or parts in the drawings are not necessarily drawn to scale. Obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0023] Figure 1 This is a schematic diagram of the existing technology; Figure 2 This is a schematic diagram of the structure of the present invention; Figure 3 This is a schematic diagram of the pressure block in the present invention; Figure 4 This is a cross-sectional view of the pressure block in this invention.

[0024] Figure 5 This is a flowchart illustrating the protection process for the laser in this invention.

[0025] Summary of attached labeling and identification: 1-Fiber optic coil, 2-Clad light stripper, 3-Fusion splice, 4-Fiber optic patch cord, 5-Receiver box, 6-Fiber optic placement slot structure, 7-Return light monitoring module, 8-Pressure block, 61-Fiber optic placement slot, 62-Suspended slot, 63-Prepared fiber optic placement slot. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] In this document, suffixes such as "module," "part," or "unit" used to denote elements are used only for the purpose of illustrative purposes and have no specific meaning in themselves. Therefore, "module," "part," or "unit" may be used interchangeably.

[0028] In this document, the terms "upper," "lower," "inner," "outer," "front," "rear," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated 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.

[0029] In this document, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0030] In this document, "and / or" includes any and all combinations of one or more of the listed related items.

[0031] In this article, "multiple" means two or more, that is, it includes two, three, four, five, etc.

[0032] Example 1: like Figure 2 As shown, this embodiment provides a return light processing device, including a cladding light stripper 2, an optical fiber placement slot structure 6, and a return light monitoring module 7.

[0033] The input-side fiber coil 1 of the cladding light stripper 2 is fixed, and the output pigtail of the cladding light stripper 2 is prepared with a spherical end face to regulate the return light transmission path and suppress end face reflection; the fiber placement slot structure 6 is provided with a plurality of fiber placement slots 61, and the pigtail is fixed in the fiber placement slots 61; the return light monitoring module 7 is located in the optical path to collect the return light signal and adjust the optical power and / or protect the laser based on the collected return light signal.

[0034] This invention eliminates the need for the fiber optic patch cord 4 and receiver box 5 required in traditional solutions. It solves the problems of low space utilization, high production and maintenance costs, and insufficient safety and reliability in existing technologies by directly burning the spherical end of the cladding stripper 2, fixing the fiber optic cable in the placement slot 61, and integrating intelligent backlight monitoring into an integrated design. This device controls the returned light through passive optical suppression and active intelligent protection. The passive layer utilizes the spherical end face of the fiber optic cable to deflect most of the returned light off its original transmission path, preventing it from returning to the laser's core components. The active layer uses the backlight monitoring module 7 to collect the remaining leakage light signal in real time, dynamically adjust the monitoring accuracy, and immediately trigger laser protection actions in case of an anomaly.

[0035] Specifically, the cladding light stripper 2 is used to remove stray light and residual pump light transmitted in the fiber cladding, preventing them from accumulating inside the laser and causing overheating and burnout. The input fiber of the cladding light stripper 2 needs to be pre-coiled and fixed, with a coil diameter typically of 15-20 cm. This increases the transmission path length of the cladding light, improves the stripping efficiency, and avoids increased optical loss due to excessive fiber bending.

[0036] The spherical end face is located at the end of the output pigtail of the cladding optical stripper 2 and is fabricated using a gradient fusion arc sintering process. When the reverse-propagating return light is incident on the spherical end face, due to the refraction effect of the curved surface of the sphere, the light will diverge and bend in various directions, deviating from the original fiber core transmission path, and eventually dissipate in the air, unable to enter the cladding optical stripper 2 and the laser resonant cavity.

[0037] The fiber optic placement slot structure 6 is equipped with multiple fiber optic placement slots 61 for securing normally functioning pigtails. Additionally, the fiber optic placement slot structure 6 has 2-3 spare fiber optic placement slots 61 pre-installed. When the spherical end face of a pigtail is damaged, it is not necessary to disassemble the entire device; simply re-cut and re-ball the pigtail from the cladding stripper 2 and fix it to an adjacent spare slot, significantly reducing repair time.

[0038] In this embodiment, the optical fiber is fixed by filling the optical fiber placement groove 61 with a photocurable adhesive with a refractive index of 1.48-1.54 to fix the pigtail as a whole. This refractive index range is close to the refractive index of the optical fiber cladding, which can effectively prevent additional light reflection at the fixing point. During curing, ultraviolet light with a wavelength of 220-260nm is used for irradiation, resulting in fast curing speed and high bonding strength.

[0039] The return light monitoring module 7 is used to monitor the remaining return light power in the optical path in real time, dynamically adjust the monitoring accuracy, and immediately trigger the laser protection action when the return light power exceeds the safety threshold to prevent permanent damage to the core components. Its structure includes a photodetector PD, a transimpedance amplifier TIA, an analog-to-digital converter ADC, and a microcontroller unit MCU connected in sequence. The photodetector is used to collect the return light signal, and the output terminal of the microcontroller unit is connected to the resistance control terminal of the transimpedance amplifier and the drive control terminal of the laser, respectively, to adjust the resistance of the transimpedance amplifier and execute the laser protection action. The microcontroller unit is configured as follows: Acquire the return optical signal fed back by the photodetector; When the returned optical power is higher than the preset strong signal threshold, the formula f=f r -k1 adjusts the resistance of the transimpedance amplifier; when the returned optical power is lower than the preset weak signal threshold, the formula f=f r +k2 adjusts the transimpedance amplifier's resistance value; where f is the adjusted transimpedance amplifier's resistance value, fr is the current transimpedance amplifier's resistance value, k1 is the transimpedance amplifier's adjustment step under a strong signal, and k2 is the transimpedance amplifier's adjustment step under a weak signal. When the real-time acquired return optical power exceeds the safety threshold, a control signal is sent to the laser driver module to perform a protection action by reducing the drive current or directly shutting down the laser.

[0040] A photodetector (PD) is placed in the optical path to collect the returned optical signal in real time and convert the optical signal into a weak current signal.

[0041] The transimpedance amplifier (TIA) converts the current signal output by the PD into a voltage signal, and its feedback resistor value can be dynamically adjusted by the MCU.

[0042] The analog-to-digital converter (ADC) converts the analog voltage signal output by the TIA into a digital signal, which is then sent to the MCU for processing.

[0043] The microcontroller unit (MCU) serves as the control core of the entire module, and its output terminals are connected to the resistance control terminal of the TIA and the drive control terminal of the laser, respectively.

[0044] When the real-time returned optical power is higher than the preset strong signal threshold f max When the current feedback resistor value of TIA is lowered by a preset step value k1, the amplification factor is reduced to prevent amplifier saturation; when the real-time returned optical power is lower than the preset weak signal threshold f... min When the current feedback resistance value of the TIA is increased by a preset step value k2, the amplification factor is increased, thereby improving the monitoring accuracy of weak signals. When the returned optical power is within the normal range, the TIA resistance value remains unchanged.

[0045] like Figure 5As shown, the MCU has a preset laser safety threshold. When the real-time acquired return light power exceeds this threshold, it indicates that the spherical end face cannot completely block the abnormally strong return light. The MCU immediately sends a control signal to the laser driver module to perform a protection action by reducing the drive current or directly shutting down the laser, thus preventing the core components from being burned out due to continuous impact from the return light.

[0046] like Figure 3 , Figure 4 As shown, in some embodiments, the optical fiber of the spherical end face section is suspended; it also includes a pressure block 8, which is disposed on the top of the optical fiber placement groove structure 6 and is used to seal and isolate the end face of the suspended optical fiber.

[0047] If the spherical end face directly contacts or is close to the surface of a structural component, a small amount of leaked high-power laser light will be absorbed by the component, causing a rapid increase in local temperature. This can lead to carbonization of the component surface or, in severe cases, instantaneous burning of the fiber end face, resulting in permanent damage. Furthermore, industrial lasers operate in a wide-frequency vibration environment of 10Hz-2000Hz. If the fiber is in rigid contact with the structural component, the vibration will generate periodic stress, leading to fiber fatigue and breakage. A suspended design allows the fiber's own elastic deformation to absorb vibrational energy. The divergent light emitted from the spherical end face requires sufficient space to dissipate evenly in all directions. If this space is insufficient, the divergent light will reflect multiple times within the structural component, creating localized photothermal accumulation and posing a safety hazard.

[0048] In this embodiment, the optical fiber suspension distance of the spherical end face segment is no less than 50mm from the bottom of the optical fiber placement slot structure 6, and there are no obstructions around it. To achieve the suspension purpose, in this embodiment, a suspension slot 62 is formed on the optical fiber placement slot structure 6 directly below the spherical end face segment, so that the spherical end face segment is suspended. The depth of the suspension slot 62 is set according to the suspension height requirement.

[0049] The clamping block 8 and the fiber optic placement slot structure 6 are fixed together to form a sealed cavity, achieving reliable isolation between the fiber end face and the external environment. A sealing strip is used to seal the clamping block 8 and the fiber optic placement slot structure 6 to ensure overall airtightness. After treatment, the cleanliness of the fiber end face must meet the requirements of IEC 61300-3-35 Class 0 standard.

[0050] Example 2: This embodiment provides a method for preparing a return light processing device, used to prepare the return light processing device described in Embodiment 1, the specific steps of which include: After S1 coils and fixes the input fiber of the cladding stripper, it measures the output pigtail of a preset length and cuts the end face of the output pigtail to obtain a flat and vertical fiber end face.

[0051] After stripping the coating from the input fiber of the cladding stripper, it is coiled into 3-5 loops with a standard diameter of 15-20 cm, and then evenly secured to the fiber optic tray of the laser using high-temperature resistant cable ties. The purpose is to increase the transmission path length of the cladding light, improve the cladding stripping efficiency, reduce stray light entering the subsequent optical path, avoid increased optical loss and decreased mechanical strength due to excessive fiber bending, and reserve sufficient fiber slack for subsequent repair and optical path adjustment.

[0052] After installing and fixing the cladding stripper at the corresponding position on the laser, measure the output pigtail length of 15-20m, using the end face of the fiber placement slot structure as a reference. This length ensures that after subsequent cutting, when the fiber is fixed in the placement slot, the spherical end face is positioned with a suspension height of ≥50mm, while allowing sufficient allowance for cutting and spherical burn-off.

[0053] In this embodiment, the end-face cutting is performed using an optical fiber cutting device. The cutting parameters are: cutting speed 290~310 bits; high cutting speed allows the blade to quickly slice through the optical fiber, resulting in instantaneous brittle fracture and obtaining a smooth, vertical end face, avoiding chipping, bevels, or burrs caused by slow extrusion; tension speed 18~22 bits; tension is applied slowly to ensure uniform tension during the cutting of extremely short optical fibers, preventing the fiber from breaking at unintended locations; cutting tension 560~600 bits; higher tension values ​​allow the microcracks in the optical fiber to propagate neatly, ensuring the flatness of the end face of the short fiber segment and laying the foundation for the subsequent sphere-forming process; the fiber length reserved after cutting is 5mm-7mm, which is the optimal reserved length for the sphere-forming process. Too short a length will result in insufficient sphere size, while too long a length will increase the length of the suspended section and reduce vibration resistance.

[0054] S2 performs gradient melting on the cut fiber end face to form a spherical end face with a uniform radius of curvature at the fiber end. The transmission path of the returning light is controlled by the spherical end face, and the back light reflection of the end face is suppressed.

[0055] Clean the cut fiber end face, place it in the fusion splicer fixture, and adjust the fiber position so that the end face is aligned with the axial line of the fusion splicer's discharge needle.

[0056] In this embodiment, the gradient melting process includes three stages in sequence: clean discharge, pre-melting, and main discharge.

[0057] The parameters for the clean discharge stage are a discharge power of 380~400 bits and a discharge time of 145~155 ms. The strong thermal shock wave generated by the electric arc vaporizes the tiny contaminants and dust remaining on the fiber end face, ensuring that the end face is absolutely clean and preventing impurities from forming bubbles or defects during the melting process.

[0058] The discharge power during the pre-fusion stage is 380~400 bits; this allows the fiber end face to be uniformly preheated and initially softened and melted, eliminating micro-stress on the end face and preparing for uniform spherical formation in the subsequent main discharge stage.

[0059] The discharge power of the main discharge stage is 380~400 bits, and the discharge time is 5950~6050 ms. The extremely long discharge time allows the glass material at the end of the optical fiber to be fully and uniformly heated and melted, and under the action of the glass surface tension, it spontaneously shrinks into a near-perfect spherical structure.

[0060] Molten glass material tends to minimize surface tension and will automatically shrink into a spherical shape without external interference. By precisely controlling the discharge time and power, the diameter and radius of curvature of the sphere can be accurately controlled. The sphere diameter is controlled between 0.3-0.4 mm, and the radius of curvature deviation is ≤ ±0.02 mm; the sphere surface is smooth, free of bubbles, cracks, and impurities; and the coaxiality deviation between the sphere and the optical fiber body is ≤ 0.05 mm.

[0061] S3 places the pigtail that has undergone the burn-in process into the slot of the fiber placement slot structure, fixes the pigtail with a photocurable adhesive and fills the fiber placement slot, and suspends the fiber at the spherical end face.

[0062] Place the pigtail that has undergone the burn-in process straight into the main slot of the fiber placement slot structure. Adjust the position of the fiber so that the spherical end face is completely suspended, with a suspension distance of ≥50mm from the bottom of the structure. The length of the suspended section is controlled between 8-12mm.

[0063] A light-curing adhesive with a refractive index of 1.48~1.54 is used. This refractive index is close to that of the fiber cladding, which can effectively reduce light reflection at the fixing point. The adhesive is slowly injected into the fiber placement groove until it is completely filled, ensuring that the fiber is completely wrapped and there are no air bubbles. The adhesive is then irradiated with deep ultraviolet light with a wavelength of 220-260nm for 30-60 seconds to allow the adhesive to fully cure.

[0064] Place the pressure block on top of the fiber optic placement slot structure, ensuring that the suspended fiber optic section is positioned precisely within the suspended slot of the fiber optic placement slot structure. Tighten the screws at both ends of the pressure block evenly, compressing the sealing strip of the fiber optic placement slot structure to deform the sealing strip and fill the gap between them, thus forming a seal.

[0065] After sealing, the cleanliness of the fiber end face meets the IEC 61300-3-35 Class 0 standard; the overall protection level reaches IP65, and it can pass dust and waterproof tests; the clamping force is moderate, and there is no fiber extrusion deformation.

[0066] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0067] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A return light processing device, characterized in that: Includes cladding stripper, fiber placement slot structure and backlight monitoring module; The input fiber coil of the cladding stripper is fixed, and the output pigtail of the cladding stripper is prepared with a spherical end face to regulate the return light transmission path and suppress end face reflection; the fiber placement slot structure is provided with several fiber placement slots, and the pigtail is fixed in the fiber placement slots; the return light monitoring module is located in the optical path to collect the return light signal and adjust the optical power and / or protect the laser based on the collected return light signal.

2. The return light processing device according to claim 1, characterized in that: The backlight monitoring module includes a photodetector, a transimpedance amplifier, an analog-to-digital converter, and a microcontroller unit connected in sequence. The photodetector is used to collect the backlight signal, and the output terminal of the microcontroller unit is connected to the resistance control terminal of the transimpedance amplifier and the drive control terminal of the laser, respectively, to adjust the resistance of the transimpedance amplifier and execute laser protection actions. The microcontroller unit is configured to: Acquire the return optical signal fed back by the photodetector; When the returned optical power is higher than the preset strong signal threshold, the formula f=f r -k1 adjusts the resistance of the transimpedance amplifier; when the returned optical power is lower than the preset weak signal threshold, the formula f=f r +k2 adjusts the transimpedance amplifier's resistance value; where f is the adjusted transimpedance amplifier's resistance value, fr is the current transimpedance amplifier's resistance value, k1 is the transimpedance amplifier's adjustment step under a strong signal, and k2 is the transimpedance amplifier's adjustment step under a weak signal. When the real-time acquired return optical power exceeds the safety threshold, a control signal is sent to the laser driver module to perform a protection action by reducing the drive current or directly shutting down the laser.

3. The return light processing device according to claim 1, characterized in that: The optical fiber placement slot structure is pre-installed with a spare optical fiber placement slot.

4. The return light processing device according to claim 1, characterized in that: The fiber placement slot is filled with a photocurable adhesive with a refractive index of 1.48~1.54 to fix the pigtail.

5. The return light processing device according to claim 1, characterized in that: The spherical end face section has an optical fiber suspended; it also includes a pressure block, which is located on top of the optical fiber placement slot structure and is used to seal and protect the end face of the suspended optical fiber.

6. The return light processing device according to claim 5, characterized in that: The distance between the suspended optical fiber of the spherical end face section and the bottom of the optical fiber placement slot structure shall not be less than 50mm.

7. A method for preparing a return light processing device, used to prepare the return light processing device according to any one of claims 1 to 6, characterized in that... include: After the input fiber of the cladding stripper is coiled and fixed, the output pigtail of the preset length is measured and the end face of the output pigtail is cut to obtain a flat and vertical fiber end face. The cut fiber end face is subjected to gradient melting treatment to form a spherical end face with a uniform radius of curvature at the end of the fiber. The transmission path of the returning light is controlled by the spherical end face, and the back reflection of the end face is suppressed. The pigtail that has undergone the sintering process is placed in the slot of the fiber placement groove structure. The pigtail is fixed and the fiber placement groove is filled with a photocurable adhesive. The fiber of the spherical end face section is suspended.

8. The method for preparing a return light processing device according to claim 7, characterized in that: The end face cutting is performed using an optical fiber cutting device with cutting parameters of cutting speed 290~310 bits, tension speed 18~22 bits, cutting tension 560~600 bits, and the reserved length of the optical fiber after cutting is 5mm-7mm.

9. The method for preparing a return light processing device according to claim 7, characterized in that: The gradient melting process includes three stages in sequence: cleaning discharge, pre-melting, and main discharge. The parameters for the clean discharge phase are: discharge power 380~400 bits, discharge time 145~155 ms; The discharge power during the pre-melting stage is 380~400 bits; The discharge power of the main discharge stage is 380~400 bits, and the discharge time is 5950~6050 ms.

10. A method for preparing a return light processing device according to claim 7, characterized in that: The photocurable adhesive has a refractive index of 1.48-1.54 and is cured using ultraviolet light with a wavelength of 220-260nm.

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