A system for evaluating the quality of fusion of a thulium-doped fiber containing a base

Abstract

The utility model relates to a kind of evaluation optical path systems of base-containing thulium-doped fiber fusion quality, belong to optical fiber fusion technical field.It includes thulium-doped fiber oscillator module and return light monitoring module, the thulium-doped fiber oscillator module includes sequentially arranged pump light source, beam combiner assembly, high reflection grating, base-containing thulium-doped fiber, low reflection grating, cladding light stripper, light output port and second optical power meter, the output fiber of high reflection grating is connected with the input fiber of low reflection grating by base-containing thulium-doped fiber, forms the first melting point and second melting point of base-containing thulium-doped fiber;The return light monitoring module includes beam combiner assembly input end signal optical fiber, dichroic mirror and first optical power meter.The application structure is simple and convenient to operate, solves the subjective error of the fusion point fusion quality evaluation existing in the field of optical fiber fusion technology, long detection time and high detection cost problem, so that base-containing thulium-doped fiber melting point fusion quality can be accurately evaluated.

Description

Technical Field

[0001] This utility model relates to an optical path system for evaluating the splicing quality of thulium-doped optical fibers with a base, belonging to the field of optical fiber splicing technology. Background Technology

[0002] The melting temperature of the thulium-doped fiber fusion splice base layer is lower than that of the core and cladding layers. During fiber end-face fusion splicing, if the splicing parameters are poor, the deformation of the fusion layer and core / cladding layers at the active fiber end face will be inconsistent, leading to significant changes in stress and refractive index distribution at the splice point. This greatly affects the coupling of the fiber core light at the splice point, resulting in output power fluctuations and impacting laser performance. Therefore, thulium-doped fiber lasers have extremely high requirements for the splice quality at the fusion point. Currently, existing fiber fusion splicing technologies cannot achieve lossless splicing; both active and passive fibers require the removal of the coating layer before splicing. Poor splice quality leads to increased splice loss and light leakage, and significantly higher temperatures at and around the splice point, further promoting changes in stress and refractive index distribution at the splice point. Localized high temperatures, uneven stress and refractive index distribution are detrimental to the stable operation of fiber lasers and may even cause internal fiber burnout.

[0003] Traditional testing methods primarily rely on visual observation of fiber optic fusion splice images for judgment, which is inherently subjective. Furthermore, due to the presence of the base layer, fusion splicers are prone to false alarms such as thermal spots and air bubbles when splicing thulium-doped fiber with a base layer to passive fiber. The splice loss and angle deviation data displayed by the fusion splicer are also inaccurate, making it impossible to accurately assess the fusion splice quality. Additionally, existing fiber optic fusion splice quality testing devices are all independent testing systems, unable to accurately assess fusion splice quality under normal laser operating conditions. Summary of the Invention

[0004] The technical problem to be solved by this utility model is to provide an optical path system for evaluating the splice quality of thulium-doped optical fibers with a base, which simplifies operation, shortens detection time, reduces detection costs, and reduces subjective errors, so that the splice quality of thulium-doped optical fibers with a base can be accurately evaluated.

[0005] The technical solution adopted by this utility model to solve the above problems is as follows: an optical path system for evaluating the splicing quality of thulium-doped fiber with a base, including a thulium-doped fiber oscillator module and a return light monitoring module. The thulium-doped fiber oscillator module includes a pump light source, a bundle combiner assembly, a high-reflectivity grating, a thulium-doped fiber with a base, a low-reflectivity grating, a cladding light stripper, an optical output port, and a second optical power meter arranged in sequence. The output fiber of the high-reflectivity grating is connected to the input fiber of the low-reflectivity grating through the thulium-doped fiber with a base, forming the first melting point and the second melting point of the thulium-doped fiber with a base.

[0006] The pump light source is coupled to the input end of the high-reflectivity grating via a beam combiner assembly, and injected into the thulium-doped fiber with a base through the high-reflectivity grating. The high-reflectivity grating, the thulium-doped fiber with a base, and the low-reflectivity grating combine to form a resonant cavity. The pump light oscillates back and forth between the high-reflectivity grating and the low-reflectivity grating, and is absorbed and converted into laser light. Most of the laser light is output from the low-reflectivity grating end to the cladding light stripper, and then output as a single-mode laser light from the optical output port. The second optical power meter is used to monitor the change in single-mode laser power in real time.

[0007] The return light monitoring module includes a signal fiber at the input end of the combiner assembly, a dichroic mirror, and a first optical power meter. One end of the signal fiber at the input end of the combiner assembly is beveled to suppress end-face reflection. A small portion of the laser light is reflected back to the signal fiber at the input end of the combiner assembly after being reflected from the end faces and fusion splices in the laser optical path. The return light output from the signal fiber at the input end of the combiner assembly is filtered by the dichroic mirror 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.

[0008] The pump light source is provided with n, and the bundle combiner assembly includes n pump optical fibers, 1 signal optical fiber and 1 output optical fiber.

[0009] Compared with existing technologies, the advantages of this invention are as follows: A system and method for evaluating the fusion splice quality of thulium-doped fiber with a base, which evaluates the fusion splice quality by analyzing the relative change between 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, solving the problems of large subjective errors, long detection time, and high detection costs in the field of fiber optic fusion splice quality evaluation, thus enabling accurate evaluation of the fusion splice quality of thulium-doped fiber with a base. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of an optical path system for evaluating the splicing quality of thulium-doped optical fibers with a base, according to an embodiment of the present invention.

[0011] Figure 2 This is a graph showing the relationship between laser power and reflected light power.

[0012] In the figure, 1 is the first optical power meter, 2 is the dichroic mirror, 3 is the pump source, 4 is the beam combiner, 5 is the high-reflectivity grating, 6 is the first melting point, 7 is the thulium-doped fiber with the base, 8 is the second melting point, 9 is the low-reflectivity grating, 10 is the cladding light stripper, 11 is the optical output port, and 12 is the second optical power meter. Detailed Implementation

[0013] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0014] like Figure 1As shown, this embodiment of an optical path system for evaluating the splice quality of thulium-doped fiber with a base includes a thulium-doped fiber oscillator module and a return light monitoring module.

[0015] The thulium-doped fiber oscillator module includes, in sequence, six pump light sources 3, a (6+1)×1 combiner 4, a high-reflectivity grating 5, a thulium-doped fiber with a base 7, a low-reflectivity grating 9, a cladding stripper 10, an optical output port 11, and a second optical power meter 12. The (6+1)×1 combiner comprises six pump fibers, one signal fiber, and one output fiber. The output fiber of the high-reflectivity grating 5 is connected to the input fiber of the low-reflectivity grating 9 through the thulium-doped fiber 7 with a base, forming the first melting point 6 and the second melting point 8 of the thulium-doped fiber 7 with a base. Six pump light sources 3 are coupled to the input end of the high-reflectivity grating 5 through a (6+1)×1 combiner 4 and injected into the thulium-doped fiber 7 with a base through the high-reflectivity grating 5. The high-reflectivity grating, the thulium-doped fiber with a base, and the low-reflectivity grating are combined to form a resonant cavity. The pump light oscillates back and forth between the high-reflectivity grating and the low-reflectivity grating and is absorbed and converted into laser light. Most of the laser light is output from the low-reflectivity grating end to the cladding light stripper 10, and then output as a single-mode laser light from the optical output port 11. The second optical power meter is used to monitor the change of single-mode laser power in real time.

[0016] The return light monitoring module includes a (6+1)×1 bundle combiner input signal fiber, a dichroic mirror 2, and a first optical power meter 1. The free end of the (6+1)×1 bundle combiner input signal fiber is beveled at an 8° angle to suppress end-face reflection. A small portion of the laser light is reflected back to the (6+1)×1 bundle combiner input signal fiber after reflection from the end faces and splice points in the laser optical path. The return light output from the (6+1)×1 bundle combiner input signal fiber is filtered by the dichroic mirror to remove the pump light before being 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. The splice quality is evaluated by analyzing the relative change between the single-mode laser power of the thulium-doped fiber oscillator module and the return light power of the return light monitoring module.

[0017] A method for evaluating the splicing quality of thulium-doped optical fibers with a substrate includes the following steps:

[0018] Step 1: Perform special discharge correction on the thulium-doped fiber with base and the passive fiber that need to be fused to determine the initial fusion power;

[0019] Step 2: Cut a section of thulium-doped fiber with a base, coil it on a water-cooled heat sink plate, and then strip the coating layer, cut the end face, and clean the splice section at both ends of the thulium-doped fiber with a base, the high-reflection grating output end, and the low-reflection grating input end in sequence.

[0020] Step 3: The two ends of the processed thulium-doped fiber with the base are fused and coated with the high-reflection grating output end and the low-reflection grating input end, respectively, to form the first melting point and the second melting point; the fusion quality of the first melting point and the second melting point is pre-evaluated based on the cutting angle, fiber angle, fusion loss, thermal image curve and angle deviation displayed by the fusion splicer.

[0021] Step 4: Check all components and optical paths on the laser platform. After confirming that everything is correct, turn on the laser. Gradually increase the pump source power output from zero until the pump source outputs full power. Record the laser power of the thulium-doped fiber oscillator module during this period using the second optical power meter. Record the return light power of the return light monitoring module using the first optical power meter.

[0022] Step 5: Plot the laser power-return light power relationship curve with laser power as the x-axis and return light power as the y-axis. When the laser power-return light power relationship curve is linear, the data test is normal. Perform linear fitting on the laser power-return light power relationship curve and evaluate the fusion quality of the melting point by comparing the slope of the fitted curve.

[0023] like Figure 2 As shown, if the slope of the blue curve is >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; if the slope of the red curve is 0.015≤0.03, the melting point welding quality is qualified, and the next test can be carried out; if the slope of the black curve is <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 need to be located.

[0024] The fusion splice quality 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 features a simple structure and convenient operation, solving the problems of large subjective errors, long detection time, and high detection costs in the field of fiber optic splicing quality evaluation, thus enabling accurate evaluation of the fusion splice quality of thulium-doped fibers with a base.

[0025] In addition to the above embodiments, this utility model also includes other implementation methods. All technical solutions formed by equivalent transformation or equivalent substitution should fall within the protection scope of the claims of this utility model.

Claims

1. An evaluation optical path system for a fusion splice quality of a thulium-doped fiber containing a pedestal, characterized by: The system includes a thulium-doped fiber oscillator module and a return light monitoring module. The thulium-doped fiber oscillator module includes a pump light source, a bundle combiner assembly, a high-reflectivity grating, a thulium-doped fiber with a base, a low-reflectivity grating, a cladding light stripper, an optical output port, and a second optical power meter arranged in sequence. The output fiber of the high-reflectivity grating is connected to the input fiber of the low-reflectivity grating through the thulium-doped fiber with a base, forming the first melting point and the second melting point of the thulium-doped fiber with a base. The pump light source is coupled to the input end of a high-reflectivity grating via a beam combiner assembly, and then injected into a thulium-doped fiber with a base through the high-reflectivity grating. The high-reflectivity grating, the thulium-doped fiber with a base, and the low-reflectivity grating combine to form a resonant cavity. The pump light oscillates back and forth between the high-reflectivity grating and the low-reflectivity grating, absorbing and converting it into laser light. Most of the laser light is output from the low-reflectivity grating end to the cladding stripper, and then output as a single-mode laser light from the optical output port. The second optical power meter is used to monitor the change in single-mode laser power in real time. A small portion of the laser light is reflected back to the signal fiber at the input end of the combiner assembly after passing through the end face and fusion splice in the laser optical path. The return light monitoring module filters the return light output from the signal fiber at the input end of the combiner assembly and collects the return light power.

2. The optical path system for evaluating the splice quality of thulium-doped optical fibers with a base according to claim 1, characterized in that: The return light monitoring module includes a signal fiber at the input end of the combiner assembly, a dichroic mirror, and a first optical power meter. One end of the signal fiber at the input end of the combiner assembly is beveled to suppress end-face reflection. The dichroic mirror filters the return light, and the first optical power meter is used to collect the return light power of the thulium-doped fiber oscillator module.

3. The optical path system for evaluating the splice quality of thulium-doped optical fibers with a base according to claim 1, characterized in that: The pump light source is provided with n, and the bundle combiner assembly includes n pump optical fibers, 1 signal optical fiber, and 1 output optical fiber.

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