Light path system and method for evaluating fusion splicing quality of thulium-doped optical fiber containing base
By designing an optical path system for evaluating the welding quality of thulium-doped optical fibers containing a base, and utilizing the power change analysis of the thulium-doped fiber oscillator module and the return light monitoring module, the subjective errors in welding quality evaluation in the existing technology and the inability to accurately evaluate under normal laser operation are solved, thus achieving efficient and accurate welding quality evaluation.
Patent Information
- Application Number
- CN202510668872.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-23
- Publication Date
- 2025-09-12
AI Technical Summary
Existing fiber fusion splicing technology cannot achieve lossless splicing, resulting in poor splicing quality and affecting laser performance. In addition, existing detection methods have subjective errors and cannot accurately evaluate the splicing quality under normal laser operation.
An optical path system for evaluating the splicing quality of thulium-doped optical fibers with a base is designed. It includes a thulium-doped fiber oscillator module and a return light monitoring module. The quality of the melting point splicing is evaluated by analyzing the relative changes in the output power of the thulium-doped fiber oscillator module and the return light power of the return light monitoring module.
The accurate evaluation of the fusion splicing quality of the thulium-doped optical fiber containing the base is achieved, which reduces the detection cost, reduces the subjective error, and can be evaluated under the normal operating environment of the laser.
Smart Images
Figure CN120629157A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to an optical path system and method for evaluating the fusion splicing quality of a thulium-doped optical fiber containing a base, and belongs to the technical field of optical fiber fusion splicing. Background Art
[0002] The melting temperature of the base layer of thulium-doped optical fiber containing a base is lower than that of the core layer and cladding. When performing fiber end-face fusion splicing, if the fusion parameters are not good, the deformation of the base layer and the core layer / cladding of the active optical fiber end face will be inconsistent, resulting in significant changes in the stress distribution and refractive index distribution at the fusion point, which greatly affects the coupling of the fiber core light at the fusion point, and then causes output power fluctuations, affecting laser performance. Therefore, thulium-doped fiber lasers have extremely high requirements for the fusion quality of the melting point. At present, existing fiber fusion splicing technology cannot achieve lossless fusion. Both active and passive optical fibers need to be stripped of the coating before fusion splicing. Poor fusion quality leads to increased loss and light leakage at the fusion point, and significantly higher temperatures at and near the fusion point, further promoting changes in stress distribution and refractive index distribution at the fusion point. Local high temperature, stress and uneven refractive index distribution are not conducive to the stable operation of the fiber laser and may even cause the internal optical fiber to burn.
[0003] Traditional inspection methods rely primarily on visual observation of fiber fusion splice images, a method subject to subjective bias. Furthermore, due to the presence of the pedestal layer, the splicer is prone to false alarms such as thermal image spots and bubbles when splicing thulium-doped fiber containing the pedestal with passive fiber. Data such as splice loss and angle deviation displayed by the splicer are also inaccurate, making it impossible to accurately assess the quality of the fusion splice. Furthermore, existing fiber fusion splice quality testing devices are all standalone test systems, unable to accurately assess the fusion splice quality under normal laser operation. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide an optical path system and method for evaluating the fusion splicing quality of a thulium-doped optical fiber containing a base in response to the above-mentioned existing technology, thereby simplifying the operation, shortening the detection time, reducing the detection cost, and reducing subjective errors, so that the fusion splicing quality of the thulium-doped optical fiber containing a base can be accurately evaluated.
[0005] The technical solution adopted by the present invention to solve the above-mentioned problem is: an optical path system for evaluating the fusion splicing quality of a thulium-doped fiber containing a base, comprising a thulium-doped fiber oscillator module and a return light monitoring module. The thulium-doped fiber oscillator module comprises a pump light source, a beam combiner assembly, a high-reflection grating, a thulium-doped fiber containing a base, a low-reflection grating, a cladding light stripper, an optical output port, and a second optical power meter arranged in sequence. The output fiber of the high-reflection grating is connected to the input fiber of the low-reflection grating via the thulium-doped fiber containing a base, thereby forming a first melting point and a second melting point of the thulium-doped fiber containing a base; The pump light source is coupled to the input end of the high-reflection grating through a beam combiner assembly and injected into the thulium-doped fiber containing the base through the high-reflection grating. The high-reflection grating, the thulium-doped fiber containing the base and the low-reflection grating form a resonant cavity. The pump light oscillates back and forth between the high-reflection grating and the low-reflection grating and is absorbed and converted into laser light. Most of the laser light is transmitted from the low-reflection grating end to the cladding light stripper and then output as single-mode laser light from the optical output port. The second optical power meter is used to monitor the changes in the single-mode laser power in real time. The return light monitoring module includes a signal optical fiber at the input end of the beam combiner component, a dichroic mirror and a first optical power meter. One end of the signal optical fiber at the input end of the beam combiner component is a beveled surface to suppress end face reflection; a small portion of the laser is reflected by each end face and fusion point in the laser optical path and then returns to the signal optical fiber at the input end of the beam combiner component. The return light output by the signal optical fiber at the input end of the beam combiner component is input to the dichroic mirror for filtration and then transmitted to the first optical power meter. The first optical power meter is used to collect the return light power of the thulium-doped fiber oscillator module.
[0006] There are n pump light sources, and the beam combiner assembly includes n pump optical fibers, one signal optical fiber and one output optical fiber.
[0007] A method for evaluating the fusion splicing quality of a thulium-doped optical fiber containing a base, the method comprising the following steps: Step 1: Perform special discharge calibration on the thulium-doped fiber with base and the passive fiber to be spliced to determine the initial splicing power; Step 2: Cut a section of thulium-doped fiber containing a base, coil it on a water-cooled heat sink, and sequentially strip the coating, cut the end faces, and clean the fusion section of the two ends of the thulium-doped fiber containing the base, the high-reflection grating output end, and the low-reflection grating input end; Step 3: The two ends of the processed thulium-doped optical fiber containing the base are respectively fused and coated and cured with the high-reflection grating output end and the low-reflection grating input end to form the first melting point and the second melting point; and the fusion quality of the first melting point and the second melting point is pre-evaluated; Step 4: Check all devices and optical paths on the laser platform. After confirming that they are correct, turn on the laser. Gradually increase the pump light source power output from zero until the pump light source outputs full power. During this period, the second optical power meter records the laser power of the thulium-doped fiber oscillator module. The first optical power meter records the return light power of the return light monitoring module.
[0008] Step 5: Draw a laser power-return light power relationship curve with laser power as the horizontal axis and return light power as the vertical axis. If the laser power-return light power relationship is linear, the data test is normal. Perform a linear fit on the laser power-return light power relationship curve. By comparing the slope of the laser power-return light power fitting curve, the welding quality of the melting point can be evaluated. When the slope of the curve is less than 0.015, it is judged that the melting point welding quality is excellent; When 0.015≤the slope of the curve<0.03, the melting point welding quality is judged to be qualified; When the slope of the curve is ≥0.03, the melting point welding quality is judged to be unqualified.
[0009] Compared with existing technologies, the present invention offers the following advantages: an optical path system and method for evaluating the splice quality of a thulium-doped fiber containing a base, which evaluates the quality of the splice by analyzing the relative changes in the output power of a thulium-doped fiber oscillator module and the return light power of a return light monitoring module. This application, with its simple structure and convenient operation, addresses the issues of large subjective errors, long testing times, and high testing costs associated with splice quality assessment in the field of optical fiber splicing technology, enabling accurate evaluation of the splice quality of thulium-doped fibers containing a base. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Figure 1 Schematic diagram of an optical path system for evaluating the fusion splicing quality of a thulium-doped optical fiber containing a base according to an embodiment of the present invention; Figure 2 is the relationship curve between laser power and return light power; In the figure, 1 is the first optical power meter, 2 is the dichroic mirror, 3 is the pump light source, 4 is the beam combiner, 5 is the high-reflection grating, 6 is the first melting point, 7 is the thulium-doped fiber with base, 8 is the second melting point, 9 is the low-reflection grating, 10 is the cladding light stripper, 11 is the optical output port, and 12 is the second optical power meter. DETAILED DESCRIPTION
[0011] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.
[0012] like Figure 1 As shown, in this embodiment, an optical path system for evaluating the fusion quality of a thulium-doped optical fiber with a base includes a thulium-doped optical fiber oscillator module and a return light monitoring module. The thulium-doped fiber oscillator module includes six pump light sources 3, a (6+1)×1 beam combiner 4, a high-reflection grating 5, a thulium-doped fiber with a base 7, a low-reflection grating 9, a cladding light stripper 10, an optical output port 11, and a second optical power meter 12. The (6+1)×1 beam combiner includes six pump fibers, one signal fiber, and one output fiber. The output fiber of the high-reflection grating 5 is connected to the input fiber of the low-reflection grating 9 through the thulium-doped fiber 7 containing the base, forming the first melting point 6 and the second melting point 8 of the thulium-doped fiber 7 containing the base; the six pump light sources 3 are coupled to the input end of the high-reflection grating 5 through the (6+1)×1 combiner 4, and are injected into the thulium-doped fiber 7 containing the base through the high-reflection grating 5. The high-reflection grating, the thulium-doped fiber containing the base and the low-reflection grating are combined to form a resonant cavity. The pump light oscillates back and forth between the high-reflection grating and the low-reflection grating and is absorbed and converted into laser light; most of the laser light is transmitted from the low-reflection grating end to the cladding light stripper 10, and then outputs single-mode laser light from the optical output port 11. The second optical power meter is used to monitor the changes in the single-mode laser power in real time.
[0013] The return light monitoring module includes a (6+1)×1 combiner input signal fiber, a dichroic mirror 2, and a first optical power meter 1. The free end of the (6+1)×1 combiner input signal fiber is beveled at an 8° angle to suppress end-face reflection. A small amount of laser light is reflected from various end faces and the fusion point in the laser optical path and then returns to the (6+1)×1 combiner input signal fiber. The return light output from the (6+1)×1 combiner input signal fiber is filtered out of the pump light by the dichroic mirror and then transmitted to the first optical power meter, which is used to collect the return light power of the thulium-doped fiber oscillator module. The quality of the melting point fusion splice is evaluated by analyzing the relative changes in the single-mode laser power of the thulium-doped fiber oscillator module and the return light power of the return light monitoring module.
[0014] A method for evaluating the fusion splicing quality of a thulium-doped optical fiber containing a base comprises the following steps: Step 1: Perform special discharge calibration on the thulium-doped fiber with base and the passive fiber to be spliced to determine the initial splicing power; Step 2: Cut a section of thulium-doped fiber containing a base, coil it on a water-cooled heat sink, and sequentially strip the coating, cut the end faces, and clean the fusion section of the two ends of the thulium-doped fiber containing the base, the high-reflection grating output end, and the low-reflection grating input end; Step 3: The two ends of the processed thulium-doped optical fiber containing the base are respectively welded and coated and cured with the high-reflection grating output end and the low-reflection grating input end to form the first melting point and the second melting point; the welding quality of the first melting point and the second melting point is preliminarily evaluated according to the parameters such as cutting angle, optical fiber angle, welding loss, thermal image curve and angle deviation displayed by the welding machine.
[0015] Step 4: Check all devices and optical paths on the laser platform. After confirming that they are correct, turn on the laser. Gradually increase the pump light source power output from zero until the pump light source outputs full power. During this period, the second optical power meter records the laser power of the thulium-doped fiber oscillator module. The first optical power meter records the return light power of the return light monitoring module.
[0016] Step 5: Draw the laser power-return light power relationship curve with laser power as the horizontal axis and return light power as the vertical axis. When the laser power-return light power is linear, the data test is normal. Perform a linear fit on the laser power-return light power relationship curve. By comparing the slope of the laser power-return light power fitting curve, the welding quality of the melting point is evaluated.
[0017] like Figure 2 As shown, the blue curve slope is greater than 0.03, the melting point welding quality is unqualified, and the first melting point 6 and the second melting point 8 need to be re-welded; 0.015≤the red curve slope is less than 0.03, the melting point welding quality is qualified, and the next test can be carried out; the black curve slope is less than 0.015, the melting point welding quality is excellent, the laser power is qualified, and the first melting point 6 and the second melting point 8 are located.
[0018] The quality of the melting point splice is evaluated by analyzing the relative changes in the output power of the thulium-doped fiber oscillator module and the return light power of the return light monitoring module. This application has a simple structure and is easy to operate. It solves the problems of large subjective errors, long detection time and high detection costs in the field of optical fiber fusion splicing technology in the evaluation of melting point splice quality, and enables accurate evaluation of the melting point splice quality of thulium-doped optical fibers containing bases.
[0019] In addition to the above embodiments, the present invention also includes other implementation methods. Any technical solutions formed by equivalent transformation or equivalent replacement should fall within the scope of protection of the claims of the present invention.
Claims
1. An optical path system for evaluating the splicing quality of a thulium-doped optical fiber containing a base, characterized by: The invention comprises a thulium-doped fiber oscillator module and a return light monitoring module. The thulium-doped fiber oscillator module comprises a pump light source, a beam combiner assembly, a high-reflection grating, a thulium-doped fiber containing a base, a low-reflection grating, a cladding light stripper, a light output port, and a second optical power meter, which are arranged in sequence. The output fiber of the high-reflection grating is connected to the input fiber of the low-reflection grating through the thulium-doped fiber containing a base, forming a first melting point and a second melting point of the thulium-doped fiber containing a base. The pump light source is coupled to the input end of the high-reflection grating through a beam combiner assembly and injected into the thulium-doped fiber containing the base through the high-reflection grating. The high-reflection grating, the thulium-doped fiber containing the base and the low-reflection grating form a resonant cavity. The pump light oscillates back and forth between the high-reflection grating and the low-reflection grating and is absorbed and converted into laser light. Most of the laser light is transmitted from the low-reflection grating end to the cladding light stripper and then output as single-mode laser light from the optical output port. The second optical power meter is used to monitor the changes in the single-mode laser power in real time. The return light monitoring module includes a signal optical fiber at the input end of the beam combiner component, a dichroic mirror and a first optical power meter. One end of the signal optical fiber at the input end of the beam combiner component is a beveled surface to suppress end face reflection; a small portion of the laser is reflected by each end face and fusion point in the laser optical path and then returns to the signal optical fiber at the input end of the beam combiner component. The return light output by the signal optical fiber at the input end of the beam combiner component is input to the dichroic mirror for filtration and then transmitted to the first optical power meter. The first optical power meter is used to collect the return light power of the thulium-doped fiber oscillator module.
2. The optical path system for evaluating the fusion splicing quality of a thulium-doped optical fiber containing a base according to claim 1, characterized in that: There are n pump light sources, and the beam combiner assembly includes n pump optical fibers, one signal optical fiber and one output optical fiber.
3. A method for evaluating the fusion splicing quality of a thulium-doped optical fiber containing a base according to any one of claims 1 to 2, characterized in that: The evaluation method comprises the following steps: Step 1: Perform special discharge calibration on the thulium-doped fiber with base and the passive fiber to be spliced to determine the initial splicing power; Step 2: Cut a section of thulium-doped fiber containing a base, coil it on a water-cooled heat sink, and sequentially strip the coating, cut the end faces, and clean the fusion section of the two ends of the thulium-doped fiber containing the base, the high-reflection grating output end, and the low-reflection grating input end; Step 3: The two ends of the processed thulium-doped optical fiber containing the base are respectively fused and coated and cured with the high-reflection grating output end and the low-reflection grating input end to form the first melting point and the second melting point; and the fusion quality of the first melting point and the second melting point is pre-evaluated; Step 4: Check all components and optical paths on the laser platform. After confirming that they are correct, turn on the laser. Gradually increase the pump light source power output from zero until the pump light source outputs full power. During this period, the second optical power meter records the laser power of the thulium-doped fiber oscillator module. The first optical power meter records the return light power of the return light monitoring module. Step 5: Draw a laser power-return light power relationship curve with laser power as the horizontal axis and return light power as the vertical axis. If the laser power-return light power relationship is linear, the data test is normal. Perform a linear fit on the laser power-return light power relationship curve. By comparing the slope of the laser power-return light power fitting curve, the welding quality of the melting point can be evaluated. When the slope of the curve is less than 0.015, it is judged that the melting point welding quality is excellent; When 0.015≤the slope of the curve<0.03, the melting point welding quality is judged to be qualified; When the slope of the curve is ≥0.03, the melting point welding quality is judged to be unqualified.