A return light test system and method based on a fiber laser

Abstract

The application relates to the field of laser technology and provides a return light testing system and method based on a fiber laser, wherein the testing system comprises a (N+1) * 1 type forward pumping combiner, a resonant cavity, a side coupling combiner and a laser output module which are connected in sequence; a first laser power meter is arranged at the input end of the forward pumping combiner; one pumping input end of the forward pumping combiner is connected with the second laser power meter; one side surface pumping fiber of the side coupling combiner is connected with the third laser power meter; the return light power size in the optical path system returned to the fiber laser, the light splitting ratio of the return light in the cladding and the fiber core and the relationship between the output laser power of the fiber laser during processing and the total return light power can be qualitatively and quantitatively measured.

Description

Technical Field

[0001] This invention relates to the field of laser technology, and in particular to a return light testing system and method based on a fiber laser. Background Technology

[0002] The main applications of industrial continuous fiber lasers are in material processing such as laser welding, laser cutting, laser cladding, and laser quenching. They utilize a focused high-energy laser beam for non-contact processing to achieve material removal, joining, strengthening, and surface modification, offering advantages such as high processing speed, small heat-affected zone, ability to process brittle and hard materials, low residual stress, and energy efficiency. Compared to traditional gas and fixed lasers, fiber lasers have unparalleled advantages in terms of energy consumption, beam quality, flexible transmission, and small size and weight. However, when high-power fiber lasers are used for processing high-reflectivity materials and in other technological applications, a portion of the laser light is reflected back into the optical path system. This significantly impacts optical components, connection points, bending areas, and high-temperature areas, leading to increased temperature, laser leakage, reduced component lifespan, and even damage to the optical path system. Furthermore, the forward and reverse propagation of the laser light may interfere under certain conditions, greatly increasing nonlinear effects, mode instability, and optical discharge effects, resulting in short-term instability and long-term power degradation. Therefore, backlighting poses a fatal threat to the safe and stable operation of high-power fiber lasers. It is very important to reduce, control, and warn of backlighting, improve the ability to resist backlighting, and reduce the impact of backlighting on the optical path system of high-power fiber lasers. For example, patents CN202021458491.1 and CN202011536337.6 propose lasers with reduced backlighting resistance and impact.

[0003] However, reducing, controlling, and providing early warning of backlighting, improving anti-backlighting capabilities, and minimizing its impact all depend on accurately and completely testing the actual backlight power in the optical path system under different processing conditions. Only by knowing the magnitude of the backlight power can we better handle and control it. Patents such as CN202121590385.3, CN201721298890.4, and CN201911134996.4 propose methods for monitoring backlighting using photodetectors and control circuits. However, these methods cannot accurately and completely measure the absolute amount of the real and complete backlighting returning to the optical path system. They only determine the presence of backlighting based on the enhancement of the photoelectric signal when it is present, without knowing the actual power of the backlighting, the power composition in the fiber core and cladding, the actual backlighting energy generated by different processing methods, or the quantitative relationship between the backlighting power and the laser processing power. Patent CN202110030943.9 can simulate the test of the return light power, but it simulates the relationship between the return light returned to the laser chip and the working performance of the laser chip. It cannot quantitatively test the total return light power returned to the optical path system during actual processing. Summary of the Invention

[0004] Based on this, embodiments of the present invention propose a return light testing system and method based on fiber lasers, which can be used to qualitatively and quantitatively measure the magnitude of the return light power in the optical path system returning to the fiber laser, the splitting ratio of the return light in the cladding and fiber core, and determine the relationship between the laser power output by the fiber laser during processing and the total return light power under different processing parameters, processing methods, and processing materials.

[0005] In a first aspect, embodiments of the present invention provide a return-beam testing system based on a fiber laser, comprising: at least one pump source, an (N+1)×1 type forward pump combiner, a resonant cavity, a side-coupled combiner, and a laser output module. The pump source is connected to the pump input end of the forward pump combiner, the output end of the forward pump combiner is connected to the input end of the resonant cavity, the output end of the resonant cavity is connected to the output end of the side-coupled combiner, and the output end of the side-coupled combiner is connected to the input end of the laser output module. The input end of the forward pump combiner is equipped with a first laser power meter, a pump input end of the forward pump combiner is connected to a second laser power meter, and a side pump fiber of the side-coupled combiner is connected to a third laser power meter.

[0006] Secondly, embodiments of the present invention provide a method for testing the reflected light from a fiber laser, comprising the following steps:

[0007] S11. Perform a first simulated return light test on the (N+1)×1 type forward pump combiner separately to obtain the first splitting ratio coefficient γ1 and the second splitting ratio coefficient γ2 of the input fiber and pump input fiber of the forward pump combiner for the first simulated return light.

[0008] S12. Perform a second simulated return light test on the side-coupled bundler separately to obtain the third splitting ratio coefficient γ3 of the side pump fiber of the side-coupled bundler for the second simulated return light.

[0009] S13. Place the forward pump combiner and the side-coupled combiner in a fiber laser-based backlight test system to construct a standard fiber laser.

[0010] S14. Drive the standard fiber laser to emit laser light, and obtain the ratio β of the output laser power P0 of the standard fiber laser to its input current I0;

[0011] S15. Apply the standard fiber laser to the processing platform, adjust the processing parameters of the standard fiber laser, and monitor the actual first actual return light passing through the forward-pumped combiner, the second actual return light passing through the side-pumped fiber of the side-coupled combiner, and the working output current I of the standard fiber laser during the processing. 测 To obtain the total retroreflection coefficient γ 总 The return light coefficient γ of the fiber core 芯 γ, the reflective coefficient of the cladding 包 ;

[0012] S16. Replace the standard fiber laser with the actual fiber laser being processed, and control the output laser of the actual fiber laser being processed according to the processing parameters described in step S15 to obtain the total return optical power P of the actual fiber laser being processed. 总回 The return optical power P of the fiber core 芯回 and the cladding return optical power P 包回 .

[0013] The beneficial effects of this invention are:

[0014] This invention provides a fiber laser-based return-beam testing system, comprising: at least one pump source, a forward pump combiner, a resonant cavity, a side-coupled combiner, and a laser output module. The pump source is connected to the pump input terminal of the forward pump combiner, the output terminal of the forward pump combiner is connected to the input terminal of the resonant cavity, the output terminal of the resonant cavity is connected to the output terminal of the side-coupled combiner, and the output terminal of the side-coupled combiner is connected to the input terminal of the laser output module. The input terminal of the forward pump combiner is equipped with a first laser power meter, a pump input terminal of the forward pump combiner is connected to a second laser power meter, and a side pump fiber of the side-coupled combiner is connected to a third laser power meter. Compared to existing technologies, the backlight testing system provided by this invention can be used to qualitatively and quantitatively measure the backlight power in the optical path system returning to the fiber laser under different processing parameters, processing methods, and processing materials, the splitting ratio of the backlight in the cladding and fiber core, and to determine the relationship between the laser power output by the fiber laser during processing and the total backlight power; and to provide basic data support for subsequent monitoring and processing of backlight to improve the anti-backlight capability of the fiber laser.

[0015] In addition, the present invention also provides a return light testing method based on fiber laser. The method uses the above-mentioned return light testing system to distinguish the return light of the fiber core and cladding, and can measure the actual return power with high accuracy. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0017] Figure 1 A structural block diagram of the fiber laser-based return light testing system provided in this embodiment of the invention;

[0018] Figure 2 A structural diagram of the fiber laser-based return-light testing system provided in this embodiment of the invention;

[0019] Figure 3 A flowchart of the fiber laser-based backlight testing method provided in this embodiment of the invention;

[0020] Figure 4 Schematic diagram of simulated backlight test on forward pumped beam combiner in this embodiment of the invention;

[0021] Figure 5The schematic diagram of the simulated backlight test on the side-coupled beam combiner in this embodiment of the invention. Detailed Implementation

[0022] 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that in this specification, the terms "first" and "second" do not limit the data or execution order, but only distinguish items with essentially the same or similar functions and effects. In this embodiment of the invention, the position of components is defined with reference to the output / emission direction of the signal light. The input end and output end refer to the input and output ends of the signal light (laser), unless specifically referring to the input and output of the pump light / pump. For example, Figure 1 The laser beam is output from the output end of the forward pump beam combiner 12 and passes sequentially through the resonant cavity 13, the side coupling beam combiner 14, and the laser output module 15.

[0024] Specifically, the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0025] This invention provides a fiber laser-based return-light testing system, such as... Figure 1 As shown, the system includes: at least one pump source 11, an (N+1)×1 type forward pump combiner 12, a resonant cavity 13, a side-coupled combiner 14, and a laser output module 15. The pump source 11 is connected to the pump input end of the forward pump combiner 12, the output end of the forward pump combiner 12 is connected to the input end of the resonant cavity 13, the output end of the resonant cavity 13 is connected to the output end of the side-coupled combiner 14, and the output end of the side-coupled combiner 14 is connected to the input end of the laser output module 15. The input end of the forward pump combiner 12 is equipped with a first laser power meter 16, one pump input end of the forward pump combiner 12 is connected to a second laser power meter 17, and one side pump fiber of the side-coupled combiner 14 is connected to a third laser power meter 18.

[0026] The (N+1)×1 type forward pump combiner 12 includes: one central fiber (not shown) and N pump input fibers (not shown), where N is a natural number. The specifications of the central fiber and the pump input fibers can be the same or different. Similarly, the side-coupled combiner 14 in this embodiment includes one central fiber (not shown) and one side pump fiber (not shown). The central fiber of both the forward pump combiner 12 and the side-coupled combiner 14 is mainly used for forward transmission of laser (signal light). Therefore, in this embodiment, the opposite ends of the central fiber are referred to as the input end (or input fiber) and the output end (or output fiber), respectively.

[0027] Furthermore, the fiber laser-based return-light testing system, such as Figure 2 As shown, it also includes: a cladding stripper 19 and a fourth laser power meter 20. The input end of the cladding stripper 19 is connected to the output end of the resonant cavity 13, and the output end of the cladding stripper 19 is connected to the input end of the side-coupled beam combiner 14. The fourth laser power meter 20 is connected to the laser output module 15. Since high-power fiber lasers easily generate a large amount of heat during processing, the laser output module 15 is a laser output head (QBH).

[0028] It should be noted that the return light testing system described in this embodiment of the invention is an all-fiber structure, which makes the entire testing system compact and easy to integrate. Each fiber includes a core and a cladding surrounding the core. The return light includes signal light and cladding light. The main return light in the fiber cladding is output from the side-pumped fiber of the side-coupled combiner 14, while the residual return light from the cladding is mainly output from the pump input end of the forward-pumped combiner 12. The return light in the fiber core is mainly output from the input fiber of the forward-pumped combiner 12.

[0029] Specifically, during the processing application of the reflected light testing system, especially when high-power lasers are used to process metal materials 21 (generally highly reflective materials), a portion of the laser light will enter the reflected light testing system in the opposite direction to the laser output direction, such as... Figure 1 and Figure 2As shown, the returned laser (return beam) L1 is coupled into the laser output module 15. The main return beam L2 in the fiber cladding is output along the pump input of the side coupler 14 and its power is measured by the third laser power meter 18. The remaining return beam L1' continues to propagate in the opposite direction of the laser output direction. After passing through the forward pump coupler 12, the remaining return beam L3 in the fiber cladding of the return beam L1' is output along the pump input of the forward pump coupler 14 and its power is measured by the second laser power meter 17. The return beam L1" in the fiber core of the return beam L1' is output along the input of the forward pump coupler 12 and its power is measured by the first laser power meter 16.

[0030] The resonant cavity 13 includes a high-reflectivity fiber grating 131, a gain fiber 132, and a low-reflectivity fiber grating 133 connected sequentially along the laser output direction.

[0031] Furthermore, embodiments of the present invention also provide a fiber laser-based backlight testing method, using the aforementioned fiber laser-based backlight testing system for testing, such as... Figure 3 As shown.

[0032] The method for testing reflected light includes the following steps:

[0033] S11. Perform a first simulated return light test on the (N+1)×1 type forward pump combiner separately to obtain the first splitting ratio coefficient γ1 and the second splitting ratio coefficient γ2 of the input fiber and pump input fiber of the forward pump combiner for the first simulated return light.

[0034] The specific steps of S11 are as follows: Figure 3 and Figure 4 As shown, a first simulated return light is input in reverse from the output fiber of the forward-pumped combiner, and its power is denoted as P. A The power of the first output simulated return light returning from the input fiber of the forward pump combiner is measured by the first laser power meter 16 and denoted as P1. The power of the second output simulated return light returning from the pump input fiber of the forward pump combiner 12 is measured by the second laser power meter 17 and denoted as P2. This is used to obtain the first splitting ratio coefficient (denoted as γ1) and the second splitting ratio coefficient (denoted as γ2) of the first simulated return light from the input fiber and pump input fiber of the forward pump combiner, respectively. Wherein, the first simulated return light P... A The relationships with the first spectroscopic ratio coefficient γ1 and the second spectroscopic ratio coefficient γ2 are respectively: γ1=P1 / P A γ2=P2 / P A .

[0035] S12. Perform a second simulated return light test on the side-coupled bundler separately to obtain the third splitting ratio coefficient γ3 of the side pump fiber of the side-coupled bundler for the second simulated return light.

[0036] The specific details of step S12 are as follows: Figure 3 and Figure 5 As shown, a second simulated return beam is input in reverse from the output fiber of the side-coupled combiner, and its power is denoted as P. B The power of the third output simulated return light returned from the side pump fiber of the side coupler 14 is measured by the third laser power meter 15 and denoted as P3, to obtain the third splitting ratio coefficient γ3 of the side pump fiber of the side coupler for the second simulated return light. The relationship between the first simulated return light P and the third splitting ratio coefficient γ3 is: γ3 = P3 / P B .

[0037] S13. Place the forward pump combiner and the side-coupled combiner in a fiber laser-based backlight test system to construct a standard fiber laser.

[0038] The specific steps of step S13 are as follows: the output end of the (N+1)×1 type forward pump combiner 12 is connected to the input end of the resonant cavity 13, the output end of the resonant cavity 13 is connected to the input end of the cladding stripper 19, the output end of the cladding stripper 19 is connected to the input end of the side-coupled combiner 14, and the output end of the side-coupled combiner 14 is connected to the input end of the laser output module 15; wherein, the input end of the forward pump combiner 12 is provided with a first laser power meter 16, one pump input end of the forward pump combiner 12 is connected to a second laser power meter 17, one side pump fiber of the side-coupled combiner 14 is connected to a third laser power meter 18, and the laser output end of the laser output head 15 is provided with a fourth laser power meter 20, so as to construct a standard fiber laser.

[0039] S14. Drive the standard fiber laser to emit laser light, and obtain the ratio β of the input current I0 of the standard fiber laser to the power P0 of its output laser light.

[0040] The specific steps of step S14 are as follows: drive the standard fiber laser to emit laser light, measure the input current I0 and the corresponding output laser power P0 when the standard fiber laser emits laser light, and calculate the ratio β of the output laser power P0 of the standard fiber laser to its input current I0, that is, β = P0 / I0.

[0041] It should be noted that, in order to improve the accuracy of the measurement of the returned light, the input current I0 of the standard fiber laser can be changed to obtain multiple sets of input current I0 and the output laser power P0 corresponding to the input current I0. The ratio β of the output laser power P0 of the standard fiber laser to its input current I0 can be obtained by linear fitting.

[0042] S15. Apply the standard fiber laser to the processing platform, adjust the processing parameters of the standard fiber laser, and monitor the actual first actual return light passing through the forward-pumped combiner, the second actual return light passing through the side-pumped fiber of the side-coupled combiner, and the working output current I of the standard fiber laser during the processing. 测 To obtain the total retroreflection coefficient γ 总 The return light coefficient γ of the fiber core 芯 γ, the reflective coefficient of the cladding 包 .

[0043] Step S15 specifically involves: applying the standard fiber laser to the processing platform, adjusting the processing parameters of the standard fiber laser in the processing application, measuring the first returned optical power P4 of the input fiber through the forward pump combiner 12 using the first laser power meter 16, measuring the second returned optical power P5 of the single pump input fiber through the forward pump combiner 12 using the second laser power meter 17, measuring the third returned optical power P6 of the side pump fiber actually passing through the side coupling combiner 14 using the third laser power meter 18, and measuring the working output current I of the standard fiber laser during the processing using a current detector (not shown). 测 To obtain the total retroreflection coefficient γ 总 The return light coefficient γ of the fiber core 芯 γ, the reflective coefficient of the cladding 包 .

[0044] Further, in step S15, the total return optical power P of the standard optical fiber is obtained based on the first splitting ratio coefficient γ1, the second splitting ratio coefficient γ2, the third splitting ratio coefficient γ3, the first return optical power P4, the second return optical power P5, and the third return optical power P6. 总 The return optical power P of the fiber core 芯 and the cladding return optical power P 包 .in,

[0045]

[0046]

[0047]

[0048] Further, in step S15, based on the ratio β of the output laser power P0 of the standard fiber laser to its input current I0, and the working output current I during the processing of the standard fiber laser... 测 The total return optical power P of the standard optical fiber 总 The return optical power P of the fiber core 芯 and the cladding return optical power P 包 The total retroreflection coefficient γ 总 The return light coefficient γ of the fiber core 芯 γ, the reflective coefficient of the cladding 包 They respectively satisfy the following relations:

[0049]

[0050]

[0051]

[0052] S16. Replace the standard fiber laser with the actual fiber laser being processed, and control the output laser of the actual fiber laser being processed according to the processing parameters described in step S15 to obtain the total return optical power P of the actual fiber laser being processed. 总回 The return optical power P of the fiber core 芯回 and the cladding return optical power P 包回 .

[0053] Step S16 specifically involves: replacing the standard fiber laser with the actual fiber laser being processed, controlling the output laser of the actual fiber laser according to the same processing parameters, and monitoring the output laser power P of the actual fiber laser using a fourth laser power meter 20. 加 And according to the total retroreflection coefficient γ 总 The return light coefficient γ of the fiber core 芯 γ, the reflective coefficient of the cladding 包 To obtain the total return optical power P of the actual processed fiber laser. 总回 The return optical power P of the fiber core 芯回 and the cladding return optical power P 包回 It satisfies the following relationship:

[0054] P 总回 =P 加 ×γ 总 P 芯回 =P 加 ×γ 芯 P 包回 =P 加 ×γ 包 .

[0055] It should be noted that, in this embodiment of the invention, the total return optical power Ptotal and the return optical power Pcore of the fiber laser actually processed can also be obtained under different operating parameters. 芯回 'and the cladding return optical power P 包回 Therefore, the embodiments of the present invention further include the step: S17, repeating steps S15 and S16 using different processing parameters to obtain the total return optical power P of the actually processed fiber laser under different processing parameters. 总回 'The return optical power P of the fiber core' 芯回 'and the cladding return optical power P 包回 '.

[0056] Step S17 specifically involves: applying the standard fiber laser to the processing platform, adjusting the standard fiber laser to use different processing parameters, and monitoring under different processing parameters: measuring the first returned optical power P4' of the input fiber through the forward-pumped combiner 12 using the first laser power meter 16; measuring the second returned optical power P5' of a single pumped input fiber through the forward-pumped combiner 12 using the second laser power meter 17; measuring the third returned optical power P6' of the side-pumped fiber through the side-coupled combiner 14 using the third laser power meter 18; and measuring the operating output current I of the standard fiber laser during processing. 测 ', to obtain the total retroreflection coefficient γ 总 ', The return light coefficient γ of the fiber core 芯 ', The calyx's reflective coefficient γ 包 Furthermore, the standard fiber laser is replaced with the actual fiber laser being processed. The output laser of the actual fiber laser is controlled according to the processing parameters corresponding to the standard fiber laser, and the output laser power P of the actual fiber laser is monitored using a fourth laser power meter 20. 加 ', to obtain the total returned optical power P of the actually processed fiber laser. 总回 'The return optical power P of the fiber core' 芯回 'and the cladding return optical power P 包回 The total return optical power P of the standard optical fiber can be obtained based on the first splitting ratio coefficient γ1, the second splitting ratio coefficient γ2, the third splitting ratio coefficient γ3, the first return optical power P4', the second return optical power P5', and the third return optical power P6'. 总 'The return optical power P of the fiber core' 芯 'and the cladding return optical power P 包 The specific formula is as follows:

[0057]

[0058]

[0059]

[0060] Wherein, the total return light coefficient γ 总 The return light coefficient γ of the fiber core 芯 γ, the reflective coefficient of the cladding 包 They respectively satisfy the following relations:

[0061]

[0062]

[0063]

[0064] The total return optical power P of the fiber laser actually processed 总回 'The return optical power P of the fiber core' 芯回 'and the cladding return optical power P 包回 ', which satisfies the following relationship:

[0065] P 总回 '=P 加 '×γ 总 ', P 芯回 '=P 加 '×γ 芯 ', P 包回 '=P 加 '×γ 包 '.

[0066] In summary, this embodiment of the invention provides a return-light testing system based on a fiber laser, comprising: at least one pump source 11, a forward pump combiner 12, a resonant cavity 13, a side-coupled combiner 14, and a laser output module 15. The pump source 11 is connected to the pump input end of the forward pump combiner 12, the output end of the forward pump combiner 12 is connected to the input end of the resonant cavity 13, the output end of the resonant cavity 13 is connected to the output end of the side-coupled combiner 14, and the output end of the side-coupled combiner 14 is connected to the input end of the laser output module 15. The input end of the forward pump combiner 12 is provided with a first laser power meter 16, one pump input end of the forward pump combiner 12 is connected to a second laser power meter 17, and one side pump fiber of the side-coupled combiner 14 is connected to a third laser power meter 18. Compared to existing technologies, the backlight testing system provided by this invention can be used to qualitatively and quantitatively measure the backlight power in the optical path system returning to the fiber laser under different processing parameters, processing methods, and processing materials, the splitting ratio of the backlight in the cladding and fiber core, and to determine the relationship between the laser power output by the fiber laser during processing and the total backlight power; and to provide basic data support for subsequent monitoring and processing of backlight to improve the anti-backlight capability of the fiber laser.

[0067] In addition, the present invention also provides a return light testing method based on fiber laser. The method uses the above-mentioned return light testing system to distinguish the return light of the fiber core and cladding, and can measure the actual return power with high accuracy.

[0068] The above provides a detailed description of a fiber laser-based return light testing system and method provided by the embodiments of the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A fiber laser-based return-light testing system, characterized in that, include: At least one pump source, (N+1)×1 type forward pump combiner, resonant cavity, side-coupled combiner, and laser output module; The forward pump combiner includes a central fiber and N pump input fibers, where N is a natural number; the side-coupled combiner includes a central fiber and a side pump fiber, and the opposite ends of the central fibers of the forward pump combiner and the side-coupled combiner are respectively referred to as the input end and the output end. The pump source is connected to the pump input terminal of the forward pump combiner, the output terminal of the forward pump combiner is connected to the input terminal of the resonant cavity, the output terminal of the resonant cavity is connected to the output terminal of the side-coupled combiner, and the output terminal of the side-coupled combiner is connected to the input terminal of the laser output module; wherein, The input end of the forward pumped combiner is equipped with a first laser power meter, one pump input end of the forward pumped combiner is connected to a second laser power meter, and one side pump fiber of the side-coupled combiner is connected to a third laser power meter. The first laser power meter is used to measure the return light power in the fiber core; the second laser power meter and the third laser power meter are used to measure the return light power in the fiber cladding; the first laser power meter is also used to measure the power of the first output simulated return light returned from the input fiber of the forward pump combiner, denoted as P1; the second laser power meter is also used to measure the power of the second output simulated return light returned from the pump input fiber of the forward pump combiner, denoted as P2, so as to obtain the first splitting ratio coefficient of the input fiber and the pump input fiber of the forward pump combiner for the first simulated return light, denoted as γ1, and the second splitting ratio coefficient, denoted as γ2; The third laser power meter is also used to measure the power of the third output simulated return light returned from the side pump fiber of the side coupler 14, denoted as P3, so as to obtain the third splitting ratio coefficient γ3 of the side pump fiber of the side coupler for the second simulated return light. The forward-pumped combiner and the side-coupled combiner together with the return-light test system constitute a standard fiber laser; The first laser power meter is also used to measure the first return optical power P4 through the input fiber of the forward pump combiner 12, the second laser power meter is also used to measure the second return optical power P5 through the single pump input fiber of the forward pump combiner 12, and the third laser power meter is also used to measure the third return optical power P6 through the side pump fiber of the side coupler 14. The first splitting ratio coefficient γ1, the second splitting ratio coefficient γ2, the third splitting ratio coefficient γ3, the first return optical power P4, the second return optical power P5, and the third return optical power P6 are used to calculate the total return optical power P of the standard fiber laser. 总 The return optical power P of the fiber core 芯 and the cladding return optical power P 包 :

2. The fiber laser-based return-light testing system as described in claim 1, characterized in that, Also includes: The system includes a cladding stripper and a fourth laser power meter. The input end of the cladding stripper is connected to the output end of the resonant cavity, and the output end of the cladding stripper is connected to the input end of the side-coupled beam combiner. The fourth laser power meter is connected to the output end of the laser output module, which is a laser output head.

3. A method for testing the reflected light from a fiber laser, employing the reflected light testing system as described in any one of claims 1-2, characterized in that, Including the following steps: S11. Perform a first simulated return light test on the (N+1)×1 type forward pump combiner separately to obtain the first splitting ratio coefficient γ1 and the second splitting ratio coefficient γ2 of the input fiber and pump input fiber of the forward pump combiner for the first simulated return light. S12. Perform a second simulated return light test on the side-coupled bundler separately to obtain the third splitting ratio coefficient γ3 of the side pump fiber of the side-coupled bundler for the second simulated return light. S13. Place the forward pump combiner and the side-coupled combiner in a fiber laser-based backlight test system to construct a standard fiber laser. S14. Drive the standard fiber laser to emit laser light, and obtain the ratio β of the output laser power P0 of the standard fiber laser to its input current I0; S15. Apply the standard fiber laser to the processing platform, adjust the processing parameters of the standard fiber laser, and monitor the actual first actual return light passing through the forward-pumped combiner, the second actual return light passing through the side-pumped fiber of the side-coupled combiner, and the working output current I of the standard fiber laser during the processing. 测 To obtain the total return light coefficient γ 总 The return light coefficient γ of the fiber core 芯 γ, the reflective coefficient of the cladding 包 ; S16. Replace the standard fiber laser with the actual fiber laser being processed, and control the output laser of the actual fiber laser being processed according to the processing parameters described in step S15 to obtain the total return optical power P of the actual fiber laser being processed. 总回 The return optical power P of the fiber core 芯回 and the cladding return optical power P 包回 .

4. The fiber laser-based return light testing method as described in claim 3, characterized in that, Step S11 specifically involves: inputting a first simulated return light in the reverse direction into the output fiber of the forward pump combiner, measuring the power P1 of the first output simulated return light returning from the input fiber of the pump combiner using a first laser power meter, and measuring the power P2 of the second output simulated return light returning from the pump input fiber of the pump combiner using a second laser power meter, in order to obtain the first splitting ratio coefficient γ1 and the second splitting ratio coefficient γ2 of the input fiber and the pump input fiber of the forward pump combiner for the first simulated return light, respectively.

5. The fiber laser-based return light testing method as described in claim 4, characterized in that, Specifically, step S12 involves: inputting a second simulated return light in reverse from the output fiber of the side-coupled bundler, and measuring the power P3 of the third output simulated return light returned from the side pump fiber of the side-coupled bundler using a third laser power meter, in order to obtain the third splitting ratio coefficient γ3 of the side pump fiber of the side-coupled bundler for the second simulated return light.

6. The fiber laser-based return light testing method as described in claim 5, characterized in that, Step S15 specifically involves: applying the standard fiber laser to the processing platform, adjusting the processing parameters of the standard fiber laser in the processing application, measuring the first returned optical power P4 of the input fiber through the forward-pumped combiner using the first laser power meter, measuring the second returned optical power P5 of the single pump input fiber through the forward-pumped combiner using the second laser power meter, measuring the third returned optical power P6 of the side-pumped fiber actually passing through the side-coupled combiner using the third laser power meter, and measuring the working output current I of the standard fiber laser during the processing using a current detector. 测 To obtain the total return light coefficient γ 总 The return light coefficient γ of the fiber core 芯 γ, the reflective coefficient of the cladding 包 .

7. The fiber laser-based return light testing method as described in claim 6, characterized in that, Step S15 further includes: obtaining the total return optical power P of the standard optical fiber based on the first splitting ratio coefficient γ1, the second splitting ratio coefficient γ2, the third splitting ratio coefficient γ3, the first return optical power P4, the second return optical power P5, and the third return optical power P6. 总 The return optical power P of the fiber core 芯 and the cladding return optical power P 包 ;in, 8. The fiber laser-based return light testing method as described in claim 7, characterized in that, In step S15, based on the ratio β between the output laser power P0 of the standard fiber laser and its input current I0, and the working output current I during the processing of the standard fiber laser... 测 The total return optical power P of the standard optical fiber 总 The return optical power P of the fiber core 芯 and the cladding return optical power P 包 The total retroreflection coefficient γ 总 The return light coefficient γ of the fiber core 芯 γ, the reflective coefficient of the cladding 包 They respectively satisfy the following relations:

9. The fiber laser-based return light testing method as described in claim 8, characterized in that, Step S16 specifically involves: replacing the standard fiber laser with the actual fiber laser being processed, controlling the output laser of the actual fiber laser according to the same processing parameters, and monitoring the output laser power P of the actual fiber laser using a fourth laser power meter. 加 And according to the total retroreflection coefficient γ 总 The return light coefficient γ of the fiber core 芯 γ, the reflective coefficient of the cladding 包 To obtain the total return optical power P of the actual processed fiber laser. 总回 The return optical power P of the fiber core 芯回 and the cladding return optical power P 包回 It satisfies the following relationship: P 总回 = P 加 ×γ 总 ,P 芯回 = P 加 ×γ 芯 , P 包回 = P 加 × γ 包 。 10. The fiber laser-based backlight testing method according to any one of claims 3 to 9, characterized in that, The process also includes the following steps: S17, repeating steps S15 and S16 using different processing parameters to obtain the total return optical power P of the actually processed fiber laser under different processing parameters. 总回 'The return optical power P of the fiber core' 芯回 'and the cladding return optical power P 包回 '.

Images