A broadband spectrum repair method for optical fiber defects and an optical fiber repair system

Abstract

The application provides a wide-spectrum repair method and a fiber repair system for optical fiber defects. The method includes the following steps: identifying defects of the optical fiber to obtain defect types and characteristic absorption peak positions; determining a wavelength range corresponding to each defect type according to the defect types and the characteristic absorption peak positions; dynamically adjusting output wavelength, power and / or irradiation time of a wide-spectrum light source to make an output spectrum cover at least a characteristic absorption band of the identified defects. Wide-spectrum laser output by the wide-spectrum light source is coupled into a fiber core of the optical fiber to be repaired for wide-spectrum irradiation. In the repair process, a transmission loss spectrum of the optical fiber is monitored in real time, and output parameters of the wide-spectrum light source are dynamically adjusted to form a closed-loop repair of "defect identification-spectrum matching-wide-spectrum irradiation-real-time monitoring-parameter adjustment-repair saturation judgment" until repair of different defects identified is completed. The application realizes efficient, synchronous and low-damage repair of multiple types of optical fiber defects and improves repair effect and efficiency.

Description

Technical Field

[0001] This invention relates to the field of fiber laser technology, and in particular to a broadband repair method and system for fiber defects. Background Technology

[0002] During high-power laser transmission or in radiation environments, optical fibers can develop various defects due to photo-induced or radiation-induced effects. These defects mainly include non-bridging oxygen hole centers (NBOHC), aluminum-oxygen hole centers (Al-OHC), STH1 defects, and STH2 defects. The formation of these defects stems from the breaking of chemical bonds or changes in the electronic structure of the fiber optic glass network, leading to enhanced light absorption. This, in turn, increases fiber transmission loss and degrades beam quality, severely limiting the lifespan and reliability of fiber optic devices in laser processing, fiber optic communication, and sensing applications.

[0003] To eliminate the aforementioned defects, existing technologies mainly employ single-wavelength bleaching light to repair specific defects. For example, irradiating optical fibers with light of a specific wavelength can partially repair NBOHC defects. However, single-wavelength bleaching light has the following inherent limitations: ① Wavelength selectivity: Light of a specific wavelength can only repair defect types that match its energy level, and is ineffective for other defects, while multiple defects often coexist in actual optical fibers; ② Incomplete repair: A single wavelength cannot achieve comprehensive repair of multiple defects, and residual defects will still lead to performance degradation; ③ Potential introduction of new defects: High-energy monochromatic light may induce new photoinduced defects in certain situations, which may exacerbate the performance degradation of the optical fiber. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a broadband repair method and system for optical fiber defects. It aims to overcome the limitations of single-wavelength / fixed-band bleached light repair technology, which cannot dynamically adapt to multiple defect combinations and lacks closed-loop feedback control. This enables intelligent, collaborative, and low-damage repair of multiple defect types in optical fibers, reduces optical fiber transmission loss, and extends the service life of optical fiber devices.

[0005] To achieve the above objectives, the present invention provides the following technical solution: On the one hand, a broadband repair method for optical fiber defects is provided, wherein the optical fiber to be repaired contains at least two different types of optically induced defects and / or radiation-induced defects, and the broadband repair method for the optical fiber to be repaired includes the following steps: (1) Defect identification is performed on the optical fiber to be repaired to obtain at least two different defect types and their characteristic absorption peak positions contained in the optical fiber to be repaired. (2) Provide a broadband light source, the broadband light source outputs tunable broadband laser, the output spectrum range covers 400nm~2000nm, and the output band and power of the broadband light source can be dynamically controlled by adjusting the pump power or repetition frequency in the broadband light source, and the band range corresponding to each defect is determined according to the defect type and its characteristic absorption peak position identified in step (1), and then the output parameters of the broadband light source are dynamically controlled. The output parameters include output band, power and / or irradiation time, so that the output spectrum at least covers the characteristic absorption band of the identified defect. The characteristic absorption band is a continuous spectral region centered on the identified characteristic absorption peak position and containing the effective absorption range of the corresponding defect. (3) The broadband laser output from the broadband light source is coupled into the core of the fiber to be repaired for broadband irradiation; (4) While performing broadband irradiation, monitor the transmission loss spectrum of the optical fiber in real time, and dynamically adjust the output parameters of the broadband light source according to the real-time monitoring results, and return to step (3) until the repair of the different defects identified in step (1) is completed.

[0006] Furthermore, the power of the broadband light source is dynamically adjusted according to the optimal repair power threshold corresponding to different defect types to prevent ineffective irradiation or secondary photo-induced damage.

[0007] On the other hand, the present invention provides a broadband repair system for optical fiber defects, used to implement the aforementioned broadband repair method for optical fiber defects, comprising: The defect identification module is used to identify defects in the optical fiber to be repaired and to obtain at least two different defect types and their characteristic absorption peak positions contained in the optical fiber to be repaired. Broadband light source, used to output tunable broadband laser; The parameter setting and control unit is connected to the defect identification module and the broadband light source. It is used to determine the band range corresponding to repair each defect based on the identified defect type and its characteristic absorption peak position, and then dynamically adjust the output parameters of the broadband light source. The output parameters include output band, power and / or irradiation time, so that the output spectrum at least covers the characteristic absorption band of the identified defect. The characteristic absorption band is a continuous spectral region centered on the identified characteristic absorption peak position and containing the effective absorption range of the corresponding defect. The coupling injection unit is used to couple and inject the broadband laser output from the dynamically controlled broadband light source into the core of the optical fiber to be repaired for broadband irradiation. The real-time monitoring and feedback unit is used to monitor the transmission loss spectrum of the optical fiber in real time during the repair process, and dynamically adjust the output parameters of the broadband light source according to the real-time monitoring results to form a closed-loop repair until the repair of the different defects identified is completed.

[0008] Existing repair schemes are generally based on fixed wavelengths or fixed narrowband light sources, which have the following inherent limitations: (1) They cannot adapt to the differences in defect types: the types and concentration combinations of defects generated by different optical fibers and different irradiation histories are different, and fixed bands cannot be dynamically matched; (2) They cannot achieve multi-defect collaborative repair: when multiple defects with large differences in characteristic absorption peaks exist in the optical fiber (such as the 614 nm of NBOHC and Al), they cannot be repaired. At 397 nm (OHC), a single narrowband light source can only repair part of the defects; (3) lack of closed-loop feedback in the repair process: the defect repair status cannot be judged in real time, which can easily lead to under-repair or over-repair, and may even introduce secondary photo-induced defects. Compared with the prior art, the beneficial effects that the present invention can produce are: This invention provides a broadband repair method and system for optical fiber defects, used to repair at least two different types of photoinduced defects and / or radiation-induced defects coexisting in an optical fiber. The method involves identifying defects in the fiber to obtain the type of defect and its characteristic absorption peak position; determining the corresponding wavelength range for repairing each defect based on the defect type and its characteristic absorption peak position; and dynamically adjusting the output parameters of the broadband light source to ensure the output spectrum at least covers the characteristic absorption band of the identified defects. The broadband laser output from the broadband light source is coupled and injected into the core of the optical fiber to be repaired for broadband irradiation. During the repair process, the transmission loss spectrum of the optical fiber is monitored in real time, and the output parameters of the broadband light source are dynamically adjusted based on the real-time monitoring results, forming a closed-loop repair until the identified defects are repaired. This invention, through defect identification, the broadband characteristics of broadband light, and dynamic feedback closed-loop optimization repair, enables simultaneous or time-divisional action on multiple defect types, overcoming the wavelength selectivity limitation of single-wavelength repair and achieving comprehensive repair of multiple photoinduced and / or radiation-induced defects in optical fibers.

[0009] This invention, through defect pre-identification and dynamic spectral matching, can automatically adapt to different defect combinations arising from different optical fibers and different irradiation histories, without the need for manual wavelength preset. This invention has a wide range of applications, applicable to all types of optical fibers to be repaired, and is particularly suitable for various rare-earth-doped optical fibers such as ytterbium-doped, erbium-doped, erbium-ytterbium co-doped, and thulium-doped fibers, as well as pure silica optical fibers, demonstrating broad prospects for engineering applications.

[0010] This invention achieves efficient and synchronous repair of various fiber optic defects through dynamic control of the output parameters of a broadband light source and closed-loop feedback optimization, significantly shortening repair time and improving repair efficiency. Combined with a real-time monitoring and feedback unit, the repair effect can be evaluated in real time and repair parameters can be dynamically adjusted, achieving precise control of the repair process.

[0011] Furthermore, this invention, through dynamic power control and saturation judgment mechanism, avoids heat accumulation or secondary photo-induced defects caused by continued irradiation after the defect has been repaired, making the repair process safer and more reliable.

[0012] This invention introduces a closed-loop mechanism of "detection-matching-regulation-optimization" into the field of optical fiber defect repair for the first time, filling the technological gap from "fixed single-wavelength bleaching" to "intelligent broadband repair". Attached Figure Description

[0013] 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. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the structure of an all-fiber laser oscillator in one embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a broadband repair system for optical fiber defects in one embodiment of the present invention; Figure 3 Figures showing the changes in photoinduced additional loss caused by different repair methods for various defect types; Explanation of the labels in the diagram: 1-1 Pump source; 1-2 Forward pump combiner; 1-3 High reflectivity fiber Bragg grating; 1-4 Ytterbium-doped fiber; 1-5 Low reflectivity fiber Bragg grating; 1-6 Cladding optical filter; 1-7 Quartz output cap; 1-8 Power meter; 2-1. Broadband detection light source; 2-2. Broadband light source; 2-3. 2×1 fiber optic coupler; 2-4. FC standard flange; 2-5. Ytterbium-doped fiber with defects to be repaired; 2-6. Fiber optic spectrometer; 2-7. Controller. Detailed Implementation

[0015] The technical solution of the present invention will now be clearly and completely described through specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. 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.

[0016] To address the limitations of existing single-wavelength or fixed-band bleaching light repair techniques, such as wavelength selectivity restrictions, difficulty in simultaneously repairing multiple defect types, and inability to dynamically adapt to different defect combinations, this invention provides a broadband repair method for optical fiber defects. The optical fiber to be repaired contains at least two different types of photoinduced defects and / or radiation-induced defects. The broadband repair method provided by this invention can repair multiple different types of defects (photoinduced defects and / or radiation-induced defects). Specifically, the method includes the following steps: (1) Defect identification is performed on the optical fiber to be repaired to obtain at least two different defect types and their characteristic absorption peak positions contained in the optical fiber to be repaired. (2) Provide a broadband light source, the broadband light source outputs tunable broadband laser, and determine the band range corresponding to each defect to be repaired according to the defect type and its characteristic absorption peak position identified in step (1), and then dynamically adjust the output parameters of the broadband light source, the output parameters including output band, power and / or irradiation time, so that the output spectrum at least covers the characteristic absorption band of the identified defect, the characteristic absorption band is a continuous spectral region centered on the identified characteristic absorption peak position and containing the effective absorption range of the corresponding defect; (3) The broadband laser output from the broadband light source is coupled into the core of the fiber to be repaired for broadband irradiation; (4) While performing broadband irradiation, monitor the transmission loss spectrum of the optical fiber in real time, and dynamically adjust the output parameters of the broadband light source according to the real-time monitoring results, and return to step (3) until the repair of the different defects identified in step (1) is completed.

[0017] Preferably, the broadband light source is a supercontinuum light source, with an output spectral range covering 400nm~2000nm. The output band and power of the broadband light source can be dynamically controlled by adjusting the pump power or repetition frequency. The above embodiment achieves a closed-loop repair process of detection-matching-controlling-optimizing. Detection identifies defects in the fiber to be repaired. Based on the defect identification results, the output parameters of the corresponding broadband light source are matched. When repairing different types of defects, the output parameters of the broadband light source are adjusted so that the output spectrum of the broadband light source covers the characteristic absorption band of the currently repaired defect. Furthermore, the transmission loss spectrum of the fiber is monitored in real time during the repair process, and the output parameters of the broadband light source are dynamically adjusted based on the real-time monitoring results. After one defect is repaired, the output parameters of the broadband light source are dynamically adjusted to repair the next defect. Simultaneously, during the fiber defect repair process, dynamically adjusting the output parameters of the broadband light source also includes: dynamically controlling the power of the broadband light source according to the optimal repair power threshold for different defect types to avoid ineffective irradiation or secondary photodamage. The power control range is 0.5 W to 50 W. The broadband repair method for optical fiber defects provided in the above embodiments can repair optical fiber defect types including but not limited to: non-bridged oxygen hole centers, aluminum oxide hole centers, STH1 defects, STH2 defects, etc.

[0018] In step (1) of this invention, defect identification of the optical fiber to be repaired can be achieved by measuring the transmission spectrum or absorption spectrum of the optical fiber to be repaired using broadband probe light (such as a deuterium tungsten halogen lamp).

[0019] If only a single type of defect is identified, the output band of the broadband light source is adjusted to cover the characteristic absorption band of the defect, and the output power of the broadband light source is dynamically adjusted to the optimal repair power threshold for the defect.

[0020] The solution provided by this invention can repair two or more different types of photoinduced defects and / or radiation-induced defects. After the fiber to be repaired is defect-identified, multiple types of defects are identified. The output band of the broadband light source is adjusted to be the union of the characteristic absorption bands of various types of defects (simultaneous irradiation), or the characteristic absorption bands of the corresponding types of defects are output sequentially according to the defect repair priority (step-by-step irradiation). The power is controlled within the range of 0.5 W to 50 W to avoid the introduction of secondary photoinduced defects due to excessive power, or the low repair efficiency due to excessively low power.

[0021] A broadband laser is coupled and injected into the core of the optical fiber to be repaired, allowing the laser to propagate along the fiber and interact with the fiber material. Since the output spectrum of the broadband laser is matched to the actual defect types, the repair light can efficiently excite carrier recombination or energy level transitions in various defects, enabling simultaneous / stepwise repair of multiple defects under a single irradiation or multiple irradiation steps.

[0022] Furthermore, in step (2) of the present invention, the output band of the broadband light source is dynamically controlled by means of: when at least two different defect types and their characteristic absorption peak positions are identified in step (1), the output band of the broadband light source is the union of the wavelength ranges of each defect characteristic absorption band, or a time-division mode is adopted so that the broadband light source outputs the bands corresponding to each defect characteristic absorption band in a predetermined time sequence.

[0023] In one embodiment, step (4) involves real-time monitoring of the transmission loss spectrum of the optical fiber while performing broadband irradiation, and dynamically adjusting the output parameters of the broadband light source based on the real-time monitoring results. Specifically, this includes: During broadband irradiation, the transmission loss spectrum of the optical fiber is monitored in real time. The absorption coefficients corresponding to the characteristic absorption peaks of each defect are extracted from the transmission loss spectrum, and the rate of change of each absorption coefficient with time is calculated. The absolute value of the rate of change is taken as the absorption decrease rate of the defect. When the absorption rate decrease of a certain defect falls below a preset threshold, it is determined that the repair of that defect is approaching saturation. At this point, the output parameters of the broadband light source are dynamically adjusted to repair other unsaturated defects in the optical fiber until all defects are repaired, at which point irradiation of the saturated defects is terminated. In this embodiment, when the absorption rate decrease of all defects falls below the preset threshold, it is determined that all defects have been repaired, and irradiation is terminated. Furthermore, if a new characteristic absorption peak (secondary defect) is detected in a certain band, the power of that band is immediately reduced or switched to another band, based on the above detection... match Regulation An optimized closed-loop mechanism enables intelligent, low-damage, and high-efficiency repair of multiple defects.

[0024] In another embodiment, a broadband repair system for optical fiber defects is provided to implement the broadband repair method for optical fiber defects, enabling simultaneous, closed-loop repair of multiple defect types in the optical fiber to be repaired. Specifically, it includes: The defect identification module is used to identify defects in the optical fiber to be repaired and to obtain at least two different defect types and their characteristic absorption peak positions contained in the optical fiber to be repaired. Broadband light source, used to output tunable broadband laser; The parameter setting and control unit is connected to the defect identification module and the broadband light source. It is used to determine the band range corresponding to repair each defect based on the identified defect type and its characteristic absorption peak position, and then dynamically adjust the output parameters of the broadband light source. The output parameters include output band, power and / or irradiation time, so that the output spectrum at least covers the characteristic absorption band of the identified defect. The characteristic absorption band is a continuous spectral region centered on the identified characteristic absorption peak position and containing the effective absorption range of the corresponding defect. The coupling injection unit is used to couple and inject the broadband laser output from the dynamically controlled broadband light source into the core of the optical fiber to be repaired for broadband irradiation. The real-time monitoring and feedback unit is used to monitor the transmission loss spectrum of the optical fiber in real time during the repair process, and dynamically adjust the output parameters of the broadband light source according to the real-time monitoring results to form a closed-loop repair until the repair of the different defects identified is completed.

[0025] The broadband light source in the above embodiments of the present invention is preferably a supercontinuum light source, comprising a pump source and a nonlinear optical fiber, wherein the nonlinear optical fiber is a photonic crystal fiber or a step-index nonlinear optical fiber. The output spectrum of the broadband light source is tuned by the pump power or the repetition frequency.

[0026] Furthermore, both the defect identification module and the real-time monitoring and feedback unit employ a broadband detection light source in conjunction with a spectrometer for detection, and the defect identification module and the real-time monitoring and feedback unit share the same broadband detection light source and spectrometer. In the above embodiments of the present invention, the broadband detection light source may be a deuterium-tungsten halide broadband light source.

[0027] On the other hand, one embodiment provides a repaired optical fiber, which is repaired using the broadband repair method for optical fiber defects provided by any of the above embodiments according to any one of claims 1-6 or the broadband repair system for optical fiber defects provided by any of the above embodiments. After repair, the transmission loss of the optical fiber in the visible to near-infrared band is significantly restored, and no unexpected secondary photodefects are generated during the repair process.

[0028] To demonstrate the effectiveness of the broadband repair method and system for optical fiber defects provided in this invention, specific examples are provided below for illustration: Example 1 of the broadband repair method and system for optical fiber defects provided by the present invention: (1) Fabrication of the optical fiber to be repaired containing photoinduced defects: Construct an all-fiber laser oscillator, wherein the all-fiber laser oscillator is as follows: Figure 1As shown, the system includes a pump source 1-1, a forward pump combiner 1-2, a high-reflectivity fiber Bragg grating 1-3, a ytterbium-doped fiber 1-4, a low-reflectivity fiber Bragg grating 1-5, a cladding optical filter 1-6, a quartz output cap 1-7, and a power meter 1-8. The ytterbium-doped fiber 1-4 is a standard double-clad ytterbium-doped fiber; the pump source 1-1 is a conventional 976 nm stable laser diode. The pump source 1-1 is connected to the forward pump combiner 1-2, and the output end of the forward pump combiner 1-2 is connected to a high-reflectivity fiber Bragg grating 1-3. The ytterbium-doped fiber 1-4 is fused between the high-reflectivity fiber Bragg grating 1-3 and the low-reflectivity fiber Bragg grating 1-5. The output end of the low-reflectivity fiber Bragg grating 1-5 is sequentially connected to a cladding optical filter 1-6 and a quartz output cap 1-7. A power meter 1-8 is located on the light-emitting side of the quartz output cap 1-7 for real-time monitoring of the laser output power. The high-reflectivity fiber Bragg grating 1-3 has a reflectivity of 99.5% and a 3dB bandwidth of 4.19 nm; the low-reflectivity fiber Bragg grating 1-5 has a reflectivity of 6% and a 3dB bandwidth of 1.01 nm.

[0029] The all-fiber laser oscillator was run continuously for a preset time to induce significant photo-induced defects in the ytterbium-doped fibers 1-4. After the operation was completed, the ytterbium-doped fibers 1-4 were removed from the all-fiber laser oscillator, the coatings at both ends of the fibers were stripped, and the fiber end faces were polished to obtain ytterbium-doped fibers with smooth end faces to be repaired.

[0030] (2) Construct a broadband repair system for optical fiber defects; To build a broadband repair system for optical fiber defects, such as... Figure 2 As shown, the system includes a broadband detection light source 2-1, a broadband light source 2-2, a 2×1 fiber optic coupler 2-3, an FC standard flange 2-4, a ytterbium-doped fiber with a defect to be repaired 2-5, a fiber optic spectrometer 2-6, and a controller 2-7. The broadband detection light source 2-1 is a deuterium-tungsten halogen broadband light source.

[0031] Broadband light source 2-1 and broadband light source 2-2 are optically combined via a 2×1 fiber optic coupler 2-3, with a coupling efficiency of not less than 80%. The coupling output of the 2×1 fiber optic coupler 2-3 is connected to the input of the ytterbium-doped fiber 2-5 to be repaired via an FC standard flange 2-4. The ytterbium-doped fiber 2-5 to be repaired is fixed on a precision spatial alignment bracket. The output of the ytterbium-doped fiber 2-5 to be repaired is connected to a fiber optic spectrometer 2-6, which is connected to a controller 2-7 to complete spectral data acquisition, storage, and real-time analysis.

[0032] The controller 2-7 integrates a defect identification module, a parameter setting and control unit, and a real-time monitoring and feedback unit.

[0033] (3) Intelligent closed-loop repair process: (3.1) Defect identification: The controller 2-7 turns on the broadband detection light source 2-1, i.e., the deuterium tungsten halogen broadband light source. The broadband detection light source 2-1 emits broadband detection light, which is received by the fiber optic spectrometer 2-6 after passing through the 2×1 fiber coupler 2-3 and the ytterbium-doped fiber 2-5 to be repaired. The transmission spectrum T1 of the ytterbium-doped fiber 2-5 before repair is obtained. The defect type and its characteristic absorption peak position contained in the ytterbium-doped fiber 2-5 to be repaired are identified from the spectrum and stored in the database of the controller 2-7. (3.2) Spectral matching: Based on the defect identification results, the controller 2-7 determines the optimal band range for repairing each defect, and then dynamically adjusts the output parameters of the broadband light source 2-2 so that its output spectrum at least covers the characteristic absorption band of each defect (the controller can dynamically adjust the output band to be the union of each characteristic absorption band, or use a time-division mode to output the corresponding sub-bands in sequence), and sets the initial power to 5 W and the irradiation time to 120 minutes. (3.3) Broadband irradiation repair: Controller 2-7 turns on broadband light source 2-2 and outputs repair laser according to the set parameters. The laser is injected into the core of the ytterbium-doped fiber 2-5 with defects to be repaired through 2×1 fiber coupler 2-3 for irradiation. (3.4) Real-time monitoring and feedback closed-loop control: During the irradiation repair process, controller 2-7 controls broadband probe light source 2-1 and fiber optic spectrometer 2-6 to continuously monitor the transmission spectrum, extract the absorption coefficients corresponding to the characteristic absorption peaks of each defect, calculate the rate of change of the absorption coefficients over time, and use the absolute value of the rate of change as the absorption decrease rate of the defect. When the absorption decrease rate of a certain defect is lower than 0.5% / min for two consecutive samplings, it is determined that the repair of the defect is approaching saturation. Controller 2-7 automatically reduces the power of that sub-band by 50% to avoid ineffective irradiation or secondary photo-induced damage, and redistributes the remaining energy to other unsaturated defects. If any new abnormal absorption peak is detected, the output of the corresponding band of broadband probe light source 2-2 is immediately reduced or suspended to avoid secondary damage, while broadband probe light source 2-1 continues to monitor.

[0034] (3.5) Repair Termination Judgment: When the characteristic absorption peak descent rate of all identified defects is less than or equal to 0.2% / min, controller 2-7 automatically shuts down broadband light source 2-2 to complete the repair of different types of defects. After the repair is completed, the transmission spectrum T2 after repair is obtained again through broadband detection light source and fiber optic spectrometer for subsequent effect evaluation.

[0035] (3.6) Effect evaluation: Substitute into formula (1) to calculate the photoinduced additional loss, and compare it with the ordinary broadband irradiation without closed-loop feedback in the subsequent two comparative examples. The results show that the repair time of the closed-loop repair group is significantly shortened, the residual loss is reduced, and no secondary photoinduced defects are detected.

[0036] The photoinduced additional loss is calculated based on transmission spectroscopy, using the following formula: Photoinduced additional loss = log (1) In the formula: L is the length of the ytterbium-doped fiber 2-5 to be repaired; T1 is the fiber transmittance before repair; T2 is the fiber transmittance after repair.

[0037] Next, Comparative Example 1 is provided: Comparative Example 1 provides a broadband repair method and system for optical fiber defects, including the following steps: (1) Prepare optical fiber with photoinduced defects, which is exactly the same as in Example 1 above; Construct an all-fiber laser oscillator, the all-fiber laser oscillator as follows: Figure 1 As shown, the system includes a pump source 1-1, a forward pump combiner 1-2, a high-reflectivity fiber Bragg grating 1-3, a ytterbium-doped fiber 1-4, a low-reflectivity fiber Bragg grating 1-5, a cladding optical filter 1-6, a quartz output cap 1-7, and a power meter 1-8. The ytterbium-doped fiber 1-4 is a standard double-clad ytterbium-doped fiber; the pump source 1-1 is a conventional 976nm stable laser diode. The pump source 1-1 is connected to the forward pump combiner 1-2, and the output end of the forward pump combiner 1-2 is connected to a high-reflectivity fiber Bragg grating 1-3. The ytterbium-doped fiber 1-4 is fused between the high-reflectivity fiber Bragg grating 1-3 and the low-reflectivity fiber Bragg grating 1-5. The output end of the low-reflectivity fiber Bragg grating 1-5 is sequentially connected to a cladding optical filter 1-6 and a quartz output cap 1-7. A power meter 1-8 is located on the light-emitting side of the quartz output cap 1-7 for real-time monitoring of the laser output power. The high-reflectivity fiber Bragg grating 1-3 has a reflectivity of 99.5% and a 3dB bandwidth of 4.19 nm; the low-reflectivity fiber Bragg grating 1-5 has a reflectivity of 6% and a 3dB bandwidth of 1.01 nm.

[0038] The all-fiber laser oscillator was run continuously for a preset time to induce significant photo-induced defects in the ytterbium-doped fibers 1-4. After the operation was completed, the ytterbium-doped fibers 1-4 were removed from the all-fiber laser oscillator, the coatings at both ends of the fibers were stripped, and the fiber end faces were polished to obtain ytterbium-doped fibers with smooth end faces to be repaired.

[0039] (2) Construct an optical fiber repair system, which is the same as the one described in Example 1 above. Figure 2The structure shown is similar, with the only difference being that the broadband light source 2-2 in the system structure is replaced with a 405nm single-wavelength bleaching light source, and the controller 2-7 does not include defect detection and closed-loop feedback control, that is, it does not perform defect identification, nor does it involve matching the output wavelength based on the defect identification result, because a 405nm single-wavelength bleaching light source is used here, and it does not involve closed-loop feedback control.

[0040] (3) Single-wavelength repair process: Turn on the 405nm single-wavelength bleaching light source, set the repair parameters: center wavelength 405nm, power 5W, and repair continuously for 120 minutes. After the repair is completed, test and record the transmission spectrum, substitute it into formula (1) to calculate the photoinduced additional loss, and complete the repair effect evaluation.

[0041] Comparative Example 2: Comparative Example 2 provides a broadband repair method and system for optical fiber defects, including the following steps: (1) Prepare optical fiber with photoinduced defects, which is exactly the same as in Example 1 above; Construct an all-fiber laser oscillator, the all-fiber laser oscillator as follows: Figure 1 As shown, the system includes a pump source 1-1, a forward pump combiner 1-2, a high-reflectivity fiber Bragg grating 1-3, a ytterbium-doped fiber 1-4, a low-reflectivity fiber Bragg grating 1-5, a cladding optical filter 1-6, a quartz output cap 1-7, and a power meter 1-8. The ytterbium-doped fiber 1-4 is a standard double-clad ytterbium-doped fiber; the pump source 1-1 is a conventional 976 nm stable laser diode. The pump source 1-1 is connected to the forward pump combiner 1-2, and the output end of the forward pump combiner 1-2 is connected to a high-reflectivity fiber Bragg grating 1-3. The ytterbium-doped fiber 1-4 is fused between the high-reflectivity fiber Bragg grating 1-3 and the low-reflectivity fiber Bragg grating 1-5. The output end of the low-reflectivity fiber Bragg grating 1-5 is sequentially connected to a cladding optical filter 1-6 and a quartz output cap 1-7. A power meter 1-8 is located on the light-emitting side of the quartz output cap 1-7 for real-time monitoring of the laser output power. The high-reflectivity fiber Bragg grating 1-3 has a reflectivity of 99.5% and a 3dB bandwidth of 4.19 nm; the low-reflectivity fiber Bragg grating 1-5 has a reflectivity of 6% and a 3dB bandwidth of 1.01 nm.

[0042] The all-fiber laser oscillator was run continuously for a preset time to induce significant photo-induced defects in the ytterbium-doped fibers 1-4. After the operation was completed, the ytterbium-doped fibers 1-4 were removed from the all-fiber laser oscillator, the coatings at both ends of the fibers were stripped, and the fiber end faces were polished to obtain ytterbium-doped fibers with smooth end faces to be repaired.

[0043] (2) Construct an optical fiber repair system, which is the same as the one described in Example 1 above. Figure 2 The structure shown is similar, with the only difference being that the broadband light source 2-2 in the system structure is replaced with a 520 nm single-wavelength bleaching light source, and the controller 2-7 does not include defect detection and closed-loop feedback control, that is, it does not perform defect identification, nor does it involve matching the output wavelength based on the defect identification result, because a 520 nm single-wavelength bleaching light source is used here, and it also does not involve closed-loop feedback control.

[0044] (3) Single-wavelength repair process: Turn on the 520nm single-wavelength bleaching light source, set the repair parameters: center wavelength 520nm, power 5W, and continuously repair for 120 minutes. After the repair is completed, test and record the transmission spectrum, substitute it into formula (1) to calculate the photoinduced additional loss, and complete the repair effect evaluation. Performance test and result analysis: To verify the effectiveness of the broadband repair method for optical fiber defects provided by this invention, three groups of samples—Example 1 (intelligent closed-loop broadband repair), Comparative Example 1 (405nm single-wavelength optical repair), and Comparative Example 2 (520nm single-wavelength optical repair)—were compared under the same test conditions. Transmission spectra before and after repair were collected using a fiber optic spectrometer, and photoinduced additional loss was calculated according to formula (1). The reduction in loss was used as the core evaluation index to compare the repair effects of different repair methods. The results are as follows: Figure 3 As shown.

[0045] Comparative Analysis of Optically Induced Additional Loss: Before repair, the ytterbium-doped fiber to be repaired exhibited significant optical defects due to long-term high-power operation, showing significant optically induced additional loss in the visible to near-infrared bands. Defect types covered non-bridged oxygen hole centers (NBOHC, characteristic absorption peak at 614nm), aluminum-oxygen hole centers (Al-OHC, characteristic absorption peaks at 397nm and 529nm), and silica substrate-related STH1 defects (characteristic absorption peak at 483nm) and STH2 defects (characteristic absorption peak at 769nm). After repair, the additional loss of all three fiber groups decreased to varying degrees, but the repair effects differed significantly. Comparative Example 2 used 520nm single-wavelength bleached light for repair. The 520nm photon energy had a low matching degree with the above defect energy levels, only having a weak repair effect on some defects. Test results showed that after repair with 520nm bleached light, the reduction in each characteristic absorption peak was limited, the overall reduction in optically induced additional loss was the smallest, and many defects still remained in large quantities. Comparative Example 1 uses 405nm single-wavelength bleached light for repair. The 405nm wavelength has a high energy level match with aluminum-oxygen hole centers (Al-OHC) and some short-wavelength defects, effectively exciting carrier transitions in these defects. Test results show that after repair with 405nm bleached light, the characteristic absorption peaks decrease significantly, and the overall loss reduction is better than the 520nm scheme, but the residual loss is still relatively high. Example 1 uses a broadband light source for broadband repair. The broadband light spectrum covers 400nm to 2000nm, completely covering the characteristic absorption bands of various defects such as non-bridging oxygen hole centers (614nm), aluminum-oxygen hole centers (397nm, 529nm), STH1 (483nm), and STH2 (769nm). The broadband light can simultaneously match the energy level structure of multiple defects, synchronously exciting carrier recombination in various defects. Test results show that after broadband restoration using a broadband light source, the photoinduced additional loss across the entire test band is significantly reduced, and the restoration effect on each characteristic absorption peak is better than that of the two single-wavelength comparisons.

[0046] Analysis of Multi-Defect Synchronous Repair Capability: The photon energy of 520nm single-wavelength bleaching light has a low matching degree with the energy levels of mainstream photoinduced defects in optical fibers, making it difficult to excite carrier transitions in various defects, thus limiting the repair capabilities. 405nm single-wavelength bleaching light has a higher matching degree with the energy levels of color center defects, effectively clearing some short-wavelength absorption defects, but due to wavelength selectivity limitations, it cannot effectively repair all types of defects. This invention utilizes a broadband light covering a wide wavelength range of 400nm-2000nm, which can simultaneously match the energy level structures of multiple defects, achieving synchronous excitation and repair of multiple defects. It is not constrained by single-wavelength selectivity, resulting in more comprehensive and thorough repair.

[0047] Comparison of transmission performance recovery: Comparative Example 2 (520nm single wavelength): The fiber transmission performance recovery is the lowest, with each characteristic absorption peak still maintaining high intensity, and the overall reduction in photoinduced additional loss is the smallest. Comparative Example 1 (405nm single wavelength): The fiber transmission performance recovery is moderate, with relatively high residual loss. Example 1 (broadband light): The fiber transmission loss is significantly reduced across the entire visible to near-infrared band, all characteristic absorption peaks are effectively suppressed, the transmission performance recovery is optimal, and the overall stability and reliability are significantly improved.

[0048] The above results demonstrate a significant difference in single-wavelength repair effectiveness: 405nm single-wavelength repair is superior to 520nm single-wavelength repair. Broadband repair is not limited by a single wavelength and can simultaneously repair multiple defects, exhibiting significantly better repair results than single-wavelength bleaching light (405nm and 520nm). The intelligent closed-loop broadband repair method proposed in this invention overcomes the selectivity limitations of traditional single-wavelength repair, achieving more efficient, comprehensive, and stable fiber defect repair, and significantly improving the lifespan and operational reliability of high-power fiber optic devices.

[0049] The method described in this invention is not only applicable to ytterbium-doped optical fibers, but also, by replacing rare earth ions, to other rare earth-doped optical fibers such as erbium-doped, erbium-ytterbium co-doped, thulium-doped, and erbium-ytterbium co-doped fibers, as well as pure quartz power transmission fibers that require improved radiation resistance.

[0050] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0051] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A broadband repair method for optical fiber defects, characterized in that, The optical fiber to be repaired contains at least two different types of optically induced defects and / or radiation-induced defects. The broadband repair method for the optical fiber to be repaired includes the following steps: (1) Defect identification is performed on the optical fiber to be repaired to obtain at least two different defect types and their characteristic absorption peak positions contained in the optical fiber to be repaired. (2) Provide a broadband light source, the broadband light source outputs tunable broadband laser, the output spectrum range covers 400nm~2000nm, and the output band and power of the broadband light source can be dynamically controlled by adjusting the pump power or repetition frequency in the broadband light source, and the band range corresponding to each defect is determined according to the defect type and its characteristic absorption peak position identified in step (1), and then the output parameters of the broadband light source are dynamically controlled. The output parameters include output band, power and / or irradiation time, so that the output spectrum at least covers the characteristic absorption band of the identified defect. The characteristic absorption band is a continuous spectral region centered on the identified characteristic absorption peak position and containing the effective absorption range of the corresponding defect. (3) The broadband laser output from the broadband light source is coupled into the core of the fiber to be repaired for broadband irradiation; (4) While performing broadband irradiation, monitor the transmission loss spectrum of the optical fiber in real time, and dynamically adjust the output parameters of the broadband light source according to the real-time monitoring results, and return to step (3) until the repair of the different defects identified in step (1) is completed.

2. The broadband repair method for optical fiber defects according to claim 1, characterized in that, In step (1), the defect identification is achieved by measuring the transmission spectrum or absorption spectrum of the optical fiber to be repaired using broadband probe light.

3. The broadband repair method for optical fiber defects according to claim 1 or 2, characterized in that, In step (2), the output band of the broadband light source is dynamically adjusted by means of: when at least two different defect types and their characteristic absorption peak positions are identified in step (1), the output band of the broadband light source is the union of the wavelength ranges of each defect characteristic absorption band; or a time-division mode is adopted so that the broadband light source outputs the bands corresponding to each defect characteristic absorption band in sequence according to the preset defect repair priority or predetermined time sequence.

4. The broadband repair method for optical fiber defects according to claim 3, characterized in that, In step (2), the output power of the broadband light source is dynamically adjusted according to the optimal repair power threshold corresponding to different defect types to prevent ineffective irradiation or secondary photo-induced damage.

5. The broadband repair method for optical fiber defects according to claim 3, characterized in that, The output power of the broadband light source can be controlled within a range of 0.5W to 50W.

6. The broadband repair method for optical fiber defects according to claim 1, 2, 4, or 5, characterized in that, Step (4) includes: During broadband irradiation, the transmission loss spectrum of the optical fiber is monitored in real time. The absorption coefficients corresponding to the characteristic absorption peaks of each defect are extracted from the transmission loss spectrum, and the rate of change of each absorption coefficient with time is calculated. The absolute value of the rate of change is taken as the absorption decrease rate of the defect. When the absorption rate of a certain defect decreases below a preset threshold, it is determined that the repair of the defect is approaching saturation. At this time, the output parameters of the broadband light source are dynamically adjusted to repair other unsaturated defects in the optical fiber until the repair of different defects is completed, and the irradiation of the saturated defects is terminated.

7. A broadband repair system for optical fiber defects, used to implement the broadband repair method for optical fiber defects as described in claim 1, characterized in that, include: The defect identification module is used to identify defects in the optical fiber to be repaired and to obtain at least two different defect types and their characteristic absorption peak positions contained in the optical fiber to be repaired. Broadband light source, used to output tunable broadband laser; The parameter setting and control unit is connected to the defect identification module and the broadband light source. It is used to determine the band range corresponding to repair each defect based on the identified defect type and its characteristic absorption peak position, and then dynamically adjust the output parameters of the broadband light source. The output parameters include output band, power and / or irradiation time, so that the output spectrum at least covers the characteristic absorption band of the identified defect. The characteristic absorption band is a continuous spectral region centered on the identified characteristic absorption peak position and containing the effective absorption range of the corresponding defect. The coupling injection unit is used to couple and inject the broadband laser output from the dynamically controlled broadband light source into the core of the optical fiber to be repaired for broadband irradiation. The real-time monitoring and feedback unit is used to monitor the transmission loss spectrum of the optical fiber in real time during the repair process, and dynamically adjust the output parameters of the broadband light source according to the real-time monitoring results to form a closed-loop repair until the repair of the different defects identified is completed.

8. The broadband repair system for optical fiber defects according to claim 7, characterized in that, The broadband light source is a supercontinuum light source, including a pump source and a nonlinear optical fiber; the nonlinear optical fiber is a photonic crystal fiber or a step-index fiber; the output spectrum of the broadband light source is tuned by the pump power or repetition frequency.

9. The broadband repair system for optical fiber defects according to claim 7, characterized in that, Both the defect identification module and the real-time monitoring and feedback unit use a broadband detection light source in conjunction with a spectral analyzer for detection, and the defect identification module and the real-time monitoring and feedback unit share the same broadband detection light source and spectral analyzer.

10. The broadband repair system for optical fiber defects according to claim 9, characterized in that, The broadband detection light source is a deuterium-tungsten halogen broadband light source.

Images