System and method for measuring extinction ratio of polarization maintaining optical fiber

Abstract

The invention discloses a polarization maintaining optical fiber extinction ratio measurement system and method, and relates to the technical field of optical fiber measurement. The polarization-maintaining optical fiber extinction ratio measuring system comprises a light source, a polarization-maintaining welding module and a polarization extinction ratio measuring module, the wavelength of the light source is the same as the working wavelength of the to-be-detected polarization maintaining fiber; the polarization-maintaining welding module is arranged between the output end of the light source and the input end of the polarization-maintaining optical fiber to be detected and is used for welding the two; the polarization extinction ratio measurement module is arranged on one side where the output end of the polarization-maintaining optical fiber to be measured is located, and the input end is connected with the output end of the polarization-maintaining optical fiber to be measured; and a processing section is arranged on the polarization maintaining optical fiber to be detected close to the output end. Based on the technical scheme disclosed by the invention, the extinction ratios of polarization-maintaining optical fibers of various sizes can be quickly and accurately measured, the deterioration influence of cladding laser and mode coupling on extinction ratio measurement can be reduced, the manual operation error is reduced, and the accuracy of the measurement result is improved, so that the measurement requirements of the extinction ratios of the polarization-maintaining optical fibers of different sizes are met.

Description

Technical Field

[0001] This invention relates to the field of optical fiber measurement technology, specifically to a polarization-maintaining fiber extinction ratio measurement system and method. Background Technology

[0002] Narrow-linewidth fiber lasers, with their high coherence, have significant application value in fields such as lidar, coherent communication, nonlinear frequency conversion, coherent beam combining, and spectral beam combining. In particular, linearly polarized narrow-linewidth fiber lasers, due to their even better coherence, offer advantages such as higher combining efficiency, higher conversion efficiency, and higher detection sensitivity, and have gradually become a key research focus for researchers in related fields.

[0003] Among them, polarization-maintaining fiber, as the most important fundamental component of narrow-linewidth fiber lasers, has polarization performance that is crucial to the laser's extinction ratio. With the development of applications, polarization-maintaining fiber has evolved from the thin-diameter fiber used in early fiber optic gyroscopes to the double-clad or multi-clad fiber used in current industrial laser fields, resulting in more varieties and more complex modes.

[0004] However, the lack of simple and efficient means to measure the extinction ratio of polarization-maintaining fibers of various sizes in related technologies has limited the application of polarization-maintaining fibers. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a polarization-maintaining fiber extinction ratio measurement system and method to solve the technical problem that existing technologies cannot simply and efficiently measure the extinction ratio of polarization-maintaining fibers of various sizes.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a polarization-maintaining fiber extinction ratio measurement system, comprising: A light source, the wavelength of which is the same as the operating wavelength of the polarization-maintaining fiber under test; A polarization-maintaining fusion splice module is disposed between the output end of the light source and the input end of the polarization-maintaining fiber under test, for connecting the output end of the light source and the input end of the polarization-maintaining fiber under test; and The polarization extinction ratio measurement module is located on the side where the output end of the polarization-maintaining fiber under test is located, and its input end is connected to the output end of the polarization-maintaining fiber under test. It is used to measure the extinction ratio of the polarization-maintaining fiber under test. Among them, a processing section is provided on the polarization-maintaining fiber under test near its output end. The processing section is used to reduce the influence of cladding light on the extinction ratio measurement.

[0007] In some embodiments, the light source is an incoherent linearly polarized light source, which is used to emit linearly polarized light with constant power as the optical signal, and the polarization extinction ratio of the linearly polarized light is greater than or equal to 25dB.

[0008] In some embodiments, the output arm of the incoherent linearly polarized light source is a standard single-mode polarization-maintaining fiber, wherein the core and cladding dimensions of the standard single-mode polarization-maintaining fiber are smaller than or equal to the core and cladding dimensions of the polarization-maintaining fiber under test.

[0009] In some embodiments, the center wavelength of the light source is: The first wavelength is used in measurements where the polarization-maintaining fiber under test is ytterbium-doped and uses related passive matching fibers; or The second wavelength is used for measurements where the polarization-maintaining fiber under test is ytterbium-doped and uses related passive matching fibers; or The third wavelength is used for measurements of polarization-maintaining fibers that are thulium-doped or thulium-holmium co-doped and related passive matching fibers.

[0010] In some embodiments, the processing section is a coating removal section, on which a high-refractive-index filter layer is coated.

[0011] In some embodiments, the polarization-maintaining fusion splicing module is a polarization-maintaining fusion splicer, which includes: The identification module is used to identify the type of polarization-maintaining fiber under test; Alignment module, used to align the slow and fast axes of polarization-maintaining fiber; and Fusion splicing module, used for splicing polarization-maintaining optical fibers.

[0012] Secondly, the present invention also provides a method for measuring the extinction ratio of polarization-maintaining fiber, which, using the above-mentioned polarization-maintaining fiber extinction ratio measurement system, includes the following steps: The output end of the light source and the input end of the polarization-maintaining fiber under test are pre-processed. Align the output end of the light source with the input end of the polarization-maintaining fiber under test, and then fusion splice them together; Secondary preprocessing is performed on the area where the output end of the polarization-maintaining fiber under test is located. Connect the output end of the polarization-maintaining fiber under test to the polarization extinction ratio measurement module, and start the measurement.

[0013] In some embodiments, the first preprocessing includes: Remove the coating from the output end of the light source and cut the output end of the light source at the specified cutting angle; Remove the coating from the input end of the polarization-maintaining fiber under test, and cut the input end of the fiber at the specified cutting angle.

[0014] In some embodiments, the secondary preprocessing includes: The coating layer in a designated area on the polarization-maintaining fiber to be tested is stripped to form a coating stripping section. High-refractive-index adhesive is uniformly applied to the stripping section of the coating layer to achieve filter mold treatment; Remove the coating from the output end of the polarization-maintaining fiber under test, and cut the output end of the polarization-maintaining fiber under test at the specified cutting angle.

[0015] In some embodiments, the output end of the alignment light source is fused to the input end of the polarization-maintaining fiber under test, including: Adjust the distance between the output end of the light source and the input end of the polarization-maintaining fiber under test; Slow-axis alignment is performed between the output end of the light source and the input end of the polarization-maintaining fiber to achieve slow-axis light transmission of linearly polarized light. The output end of the light source is fused to the input end of the polarization-maintaining fiber under test; The distance between the output end of the light source and the input end of the polarization-maintaining fiber under test is less than 100 μm.

[0016] Compared with existing technologies, the present invention provides a polarization-maintaining fiber extinction ratio measurement system and method. This system uses a polarization-maintaining fusion splicing module to fuse the polarization-maintaining fiber under test with the output end of a light source, and connects the output end of the polarization-maintaining fiber under test to a polarization extinction ratio measurement module. Simultaneously, it performs pre-measurement processing on the processing section of the polarization-maintaining fiber under test. This system requires fewer components and is simple to operate. It can not only quickly and accurately measure the extinction ratio of polarization-maintaining fibers of various sizes, but also reduce the deteriorating effect of cladding laser and mode coupling on the extinction ratio measurement, reduce human error, and improve the accuracy of measurement results, thus meeting the measurement requirements of extinction ratios of polarization-maintaining fibers of different sizes. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of a polarization-maintaining fiber extinction ratio measurement system in one embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the stripped section of the polarization-maintaining optical fiber under test in one embodiment of the present invention; Figure 3 This is a schematic flowchart of a polarization-maintaining fiber extinction ratio measurement method in one embodiment of the present invention; Figure 4 This is a schematic diagram of a preprocessing step in one embodiment of the present invention; Figure 5 This is a schematic diagram of the secondary preprocessing process in one embodiment of the present invention.

[0018] Explanation of reference numerals in the attached diagram: 1. Light source; 11. Output arm; 2. Polarization-maintaining fusion splice module; 3. Polarization-maintaining fiber under test; 31. Coating stripping section; 4. Polarization extinction ratio measurement module. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0020] To address the aforementioned technical problems, this invention provides a polarization-maintaining fiber extinction ratio measurement system and method. This system can not only quickly and accurately measure the extinction ratio of polarization-maintaining fibers of various sizes, but also reduce the deteriorating effect of cladding laser and mode coupling on the extinction ratio measurement, reduce human error, and improve the accuracy of measurement results, thereby meeting the measurement requirements of extinction ratio of polarization-maintaining fibers of different sizes.

[0021] Example 1: Please see Figure 1 The present invention provides a polarization-maintaining fiber extinction ratio measurement system, including a light source 1, a polarization-maintaining fusion splicing module 2, and a polarization extinction ratio measurement module 4; wherein, the light source 1 can emit an optical signal with the same operating wavelength as the polarization-maintaining fiber 3 under test, the polarization-maintaining fusion splicing module 2 can fusion splice the output end of the light source 1 and the input end of the polarization-maintaining fiber 3 under test, and the polarization extinction ratio measurement module 4 can measure the extinction ratio of the polarization-maintaining fiber 3 under test.

[0022] In this embodiment, the light source 1 can be selected according to different types of light sources 1 as needed. However, in order to ensure the accuracy of the measurement results, the light source 1 can preferably be an incoherent linearly polarized light source. The incoherent linearly polarized light source can emit linearly polarized light with constant power as the light signal, and the polarization extinction ratio of the linearly polarized light emitted by it is preferably greater than or equal to 25dB.

[0023] Based on this, the output arm 11 of the incoherent linear polarization source can be a standard single-mode polarization-maintaining fiber, and the core and cladding dimensions of the standard single-mode polarization-maintaining fiber are preferably smaller than or equal to the core and cladding dimensions of the polarization-maintaining fiber 3 to be tested.

[0024] For example, in one embodiment, the core and cladding dimensions of the aforementioned standard single-mode polarization-maintaining fiber can be 6 μm and 125 μm, respectively.

[0025] At this time, the dimensions of the core and cladding of the polarization-maintaining fiber 3 to be tested should be greater than or equal to the above dimensions. The combination of dimensions can be any one of the following combinations: 6 / 125µm, 10 / 125µm, 20 / 125µm, 20 / 250µm, 25 / 250µm, 30 / 250µm, 20 / 400µm, 25 / 400µm, 30 / 400µm, 30 / 600µm, and 40 / 680µm.

[0026] Meanwhile, to further improve measurement accuracy, the center wavelength of the aforementioned incoherent linearly polarized light source can be determined according to the type of polarization-maintaining fiber 3 under test. In this case, the incoherent linearly polarized light source 1 can be selected from at least linearly polarized light sources 1 with center wavelengths of the first wavelength, the second wavelength, and the third wavelength, respectively.

[0027] The first wavelength can be 1064nm, that is, the corresponding light source 1 is a linearly polarized light source 1 with a center wavelength of 1064nm; at this time, the corresponding polarization-maintaining fiber 3 to be tested can be ytterbium-doped and related passive matching fiber.

[0028] The second wavelength can be 1550nm, that is, the corresponding light source 1 is a linearly polarized light source 1 with a center wavelength of 1500nm; at this time, the corresponding polarization-maintaining fiber 3 to be tested can be erbium-doped or erbium-ytterbium co-doped and related passive matching fiber.

[0029] The third wavelength can be 1940nm, which means that the corresponding light source 1 is a linearly polarized light element with a center wavelength of 1940nm; at this time, the corresponding polarization-maintaining fiber 3 to be tested can be thulium-doped or thulium-holmium co-doped and related passive matching fibers.

[0030] It is understood that the wavelength of the light source 1 should be the same as the operating wavelength of the polarization-maintaining fiber 3 under test, while the center wavelength of the light source 1 can be determined according to the type of the polarization-maintaining fiber 3 under test.

[0031] When the polarization-maintaining fiber 3 under test is ytterbium-doped and related passive matching fiber, a linearly polarized light source 1 with a center wavelength of 1064 nm can be selected; when the polarization-maintaining fiber 3 under test is erbium-doped or erbium-ytterbium co-doped and related passive matching fiber, a linearly polarized light source 1 with a center wavelength of 1550 nm can be selected; when the polarization-maintaining fiber 3 under test is thulium-doped or thulium-holmium co-doped and related passive matching fiber, a linearly polarized light source 1 with a center wavelength of 1940 nm can be selected.

[0032] Based on this, the power and polarization extinction ratio of the linearly polarized light emitted by the incoherent linearly polarized light source can be not specifically limited. For example, in one embodiment, the power of the linearly polarized light emitted by the light source 1 can be constant at 1mW, and its polarization extinction ratio can be 28dB.

[0033] Please see Figure 1 In this embodiment, the polarization-maintaining fusion splicing module 2 is disposed between the output end of the light source 1 and the input end of the polarization-maintaining fiber 3 to be tested, and is mainly used to splice the output end of the light source 1 and the input end of the polarization-maintaining fiber 3 to be tested.

[0034] Specifically, the polarization-maintaining fusion splicing module 2 can be a polarization-maintaining fusion splicer, which can be equipped with an identification module, an alignment module, and a splicing module. The identification module can identify the type of the polarization-maintaining fiber 3 under test, the alignment module can align the fast axis and slow axis of the polarization-maintaining fiber, and the splicing module can be used to perform splicing of the polarization-maintaining fiber.

[0035] It should be noted that the specific structure of the polarization-maintaining welding machine is existing technology in this field and is not the focus of this invention, so it will not be described in detail here.

[0036] In this embodiment, the polarization extinction ratio measurement module 4 can be a polarization extinction ratio tester, which can be a complete polarization extinction ratio tester or a polarization extinction ratio test system, and can measure the polarization extinction ratio of the linearly polarized light input therein.

[0037] In this way, based on the fusion splicing of the output end of the light source 1 and the input end of the polarization-maintaining fiber 3 under test, the output end of the polarization-maintaining fiber 3 under test is connected to the input end of the polarization extinction ratio tester; with the help of the linearly polarized light emitted by the incoherent linearly polarized light source, the extinction ratio of the polarization-maintaining fiber 3 under test can be measured.

[0038] Please see Figure 2 In this embodiment, to further improve the accuracy of the measurement results, a processing section can also be set on the polarization-maintaining fiber 3 to be tested.

[0039] Specifically, the processing section can be located near the output end of the polarization-maintaining fiber 3 under test, specifically 10 cm from the output end of the polarization-maintaining fiber 3 under test, and the length of the processing section can be 10 cm. On this processing section, the coating layer on the polarization-maintaining fiber 3 under test is stripped off, forming a coating stripping section 31. High-refractive-index adhesive can be uniformly coated on the coating stripping section 31 to form a high-refractive-index adhesive filter layer (not shown in the figure).

[0040] By setting a processing section on the polarization-maintaining fiber 3 under test, removing the coating layer of the processing section, and coating the stripped section 31 to form a high-refractive-index adhesive filter layer, the polarization-maintaining fiber 3 under test is subjected to filter mode treatment. In actual measurement, the high-refractive-index adhesive filter layer can reduce the deteriorating effect of cladding laser and mode coupling on extinction ratio measurement, thereby helping to improve the accuracy of measurement results.

[0041] It should be noted that the specific position and length of the processing segment on the polarization-maintaining fiber 3 under test can be flexibly adjusted as needed, and no specific limitation is required. Similarly, the material of the high-refractive-index adhesive mentioned above is also not specifically limited, as long as its effective refractive index is greater than the effective refractive index of the inner cladding on the polarization-maintaining fiber.

[0042] Example 2: Please see Figure 3Based on the above measurement system, the present invention also provides a method for measuring the extinction ratio of polarization-maintaining fiber, comprising the following steps: A preprocessing step is performed on the output end of light source 1 and the input end of the polarization-maintaining fiber 3 under test; Align the output end of the light source 1 with the input end of the polarization-maintaining fiber 3 under test, and then fusion splice them together; Secondary preprocessing is performed on the area where the output end of the polarization-maintaining fiber 3 under test is located. Connect the output end of the polarization-maintaining fiber 3 to the polarization extinction ratio measurement module 4, and start the measurement.

[0043] In actual measurement, it is necessary to first determine the size and model of the polarization-maintaining fiber 3 to be tested, and then select a suitable light source 1 based on the size and model of the polarization-maintaining fiber 3 to be tested.

[0044] It is understandable that in practical applications, the dimensions and specifications of polarization-maintaining fibers exist according to corresponding national and industry standards; based on these standards, the dimensions and specifications of polarization-maintaining fibers can be determined in advance. Based on the dimensions and specifications of the polarization-maintaining fiber, a suitable light source 1 can be selected. The factors to consider when selecting light source 1 include at least the following: Firstly, the light source 1 is preferably an incoherent linearly polarized light source, and the incoherent linearly polarized light source can emit linearly polarized light with constant power.

[0045] By employing an incoherent linearly polarized light source, not only can a polarization reference be accurately provided, improving the accuracy of polarization-related parameter measurements, but background interference can also be suppressed, increasing the signal-to-noise ratio and measurement sensitivity. Furthermore, the incoherence can avoid interference noise, ensuring measurement stability.

[0046] Secondly, the wavelength of the light source 1 should be consistent with the working wavelength of the polarization-maintaining fiber 3 to ensure the measurement effect.

[0047] For example, in one embodiment, the wavelength of the incoherent linearly polarized light source and the operating wavelength of the polarization-maintaining fiber 3 under test can both be 1064 nm. Of course, the wavelength of the light source 1 and the operating wavelength of the polarization-maintaining fiber 3 under test can also be other wavelengths, depending on the actual parameters of the operating wavelength of the polarization-maintaining fiber 3 under test.

[0048] Third, depending on the different materials of the polarization-maintaining fiber 3 to be tested, light sources 1 with different center wavelengths can be selected.

[0049] For example, when the polarization-maintaining fiber 3 under test is ytterbium-doped and related passive matching fiber, a linearly polarized light source 1 with a center wavelength of 1064 nm can be selected; when the polarization-maintaining fiber 3 under test is erbium-doped or erbium-ytterbium co-doped and related passive matching fiber, a linearly polarized light source 1 with a center wavelength of 1550 nm can be selected; when the polarization-maintaining fiber 3 under test is thulium-doped or thulium-holmium co-doped and related passive matching fiber, a linearly polarized light source 1 with a center wavelength of 1940 nm can be selected.

[0050] Fourth, the output arm 11 of the light source 1 can be a standard single-mode polarization-maintaining fiber, and the dimensions of its core and cladding are preferably smaller than or equal to the dimensions of the core and cladding on the polarization-maintaining fiber 3 to be tested.

[0051] For example, when the core and cladding dimensions of the aforementioned standard single-mode polarization-maintaining fiber are 6µm and 125µm respectively, the core and cladding dimension combinations of the polarization-maintaining fiber 3 under test that can be used for measurement can be any one of the following combinations: 6 / 125µm, 10 / 125µm, 20 / 125µm, 20 / 250µm, 25 / 250µm, 30 / 250µm, 20 / 400µm, 25 / 400µm, 30 / 400µm, 30 / 600µm, and 40 / 680µm.

[0052] It should be noted that other parameters of light source 1 (such as the power and polarization extinction ratio of the linearly polarized light emitted by the incoherent linearly polarized light source) can be flexibly set as needed, and no specific limitation is required. For example, in one embodiment, the light signal of the incoherent linearly polarized light source can be linearly polarized light with a constant power of 1mW, and its polarization extinction ratio can be 28dB.

[0053] Please see Figure 4 After selecting light source 1, the above step "preprocessing the output end of light source 1 and the input end of the polarization-maintaining fiber 3 under test" can be started; the preprocessing operation specifically includes: Remove the coating layer from the output end of light source 1 and cut the output end of light source 1 at the specified cutting angle; Remove the coating layer from the input end of the polarization-maintaining fiber 3 under test, and cut the input end of the polarization-maintaining fiber 3 under test at the specified cutting angle.

[0054] As explained above, the output arm 11 of the incoherent linearly polarized light source is a standard single-mode polarization-maintaining fiber. By removing the coating layer from the output end of the light source 1 and the input end of the polarization-maintaining fiber 3 under test, and cutting the fibers on both sides at a specified angle, the transmission of linearly polarized light in the fibers on both sides can be optimized.

[0055] It should be noted that the specified cutting angle can be determined as needed. For example, in one embodiment, the cutting angles of the output end of the light source 1 and the input end of the polarization-maintaining fiber 3 under test can both be specified as 1°.

[0056] After completing one preprocessing step, the above step of "aligning the output end of the light source 1 with the input end of the polarization-maintaining fiber 3 under test, and splicing them together" specifically includes: Position the output end of light source 1 and the input end of the polarization-maintaining fiber 3 under test on opposite sides of the polarization-maintaining fusion splicer, and then start the polarization-maintaining fusion splicer. The polarization-maintaining fusion splicer not only aligns the slow axis of the output end of light source 1 with the input end of the polarization-maintaining fiber 3 under test, but also performs fusion splicing between the two.

[0057] It is understood that the polarization-maintaining fusion splicer used in this embodiment can have three functions: polarization-maintaining fiber type identification, automatic alignment of slow and fast axes, and polarization-maintaining fiber fusion splicing.

[0058] With the help of polarization-maintaining fiber type identification, the polarization-maintaining fusion splicer can automatically adjust alignment and splicing parameters. Based on this, through the automatic alignment function, the polarization-maintaining fusion splicer can automatically align the slow axis of the output end of light source 1 with the input end of the polarization-maintaining fiber 3 under test, ensuring slow-axis light transmission of linearly polarized light. After alignment, the polarization-maintaining fusion splicer can splice the output end of light source 1 and the input end of the polarization-maintaining fiber 3 under test.

[0059] It is important to note that when fusion splicing the output end of light source 1 and the input end of the polarization-maintaining fiber 3 under test, the distance between them can be flexibly controlled to ensure efficient transmission of linearly polarized light. For example, in one embodiment, the distance between the output end of light source 1 and the input end of the polarization-maintaining fiber 3 under test can be controlled to be less than 100 μm. Of course, the distance can also be controlled within other numerical ranges as needed, and no specific limitation is made.

[0060] Please see Figure 5 After aligning and splicing the input end of light source 1 with the input end of the polarization-maintaining fiber 3 under test, the above step "secondary preprocessing of the area where the output end of the polarization-maintaining fiber 3 under test" can be performed. The secondary preprocessing includes the following operations: The coating layer on the polarization-maintaining fiber 3 to be tested is stripped from a designated area to form the coating stripping section 31. High-refractive-index adhesive is uniformly applied to the coating layer stripping section 31 to achieve filter mold treatment; Remove the coating layer from the output end of the polarization-maintaining fiber 3 under test, and cut the output end of the polarization-maintaining fiber 3 under test at the specified cutting angle.

[0061] In practice, the coating can be stripped from a designated area near the end of the polarization-maintaining fiber 3 under test to form a stripped section 31. After stripping, a high-refractive-index adhesive can be uniformly applied to the stripped section 31 to achieve filter treatment. Then, the coating at the output end of the polarization-maintaining fiber 3 under test can be further stripped, and the output end of the polarization-maintaining fiber 3 under test can be cut at a specified cutting angle.

[0062] It is understood that the purpose of the aforementioned designated area is to define the specific location of the coating stripping section 31, which can be flexibly specified as needed. For example, in one embodiment, the designated area can be a region 10cm away from the output end of the polarization-maintaining fiber 3 under test, with an extension length of 10cm.

[0063] The aforementioned high-refractive-index adhesive refers to an adhesive or gel-like material with a high refractive index. Its specific refractive index parameter can be determined based on the effective refractive index of the quartz inner cladding on the polarization-maintaining fiber 3 under test, and is not specifically limited. For example, in one embodiment, the effective refractive index of the quartz inner cladding on the polarization-maintaining fiber 3 under test is 1.452; in this case, the high-refractive-index adhesive used can be a liquid, and its effective refractive index can be 1.492.

[0064] The coating removal and cutting operations at the output end of the polarization-maintaining fiber 3 under test can be performed in accordance with the operations at the input end of the polarization-maintaining fiber 3 under test described above, and will not be repeated here.

[0065] It should be noted that by removing the coating layer and applying a high-refractive-index filter to a designated area on the polarization-maintaining fiber 3 under test, the deteriorating effect of cladding laser and mode coupling on the extinction ratio test can be reduced, thereby improving the accuracy of the measurement results.

[0066] After completing the above-mentioned secondary preprocessing, the above steps can be performed: "Connect the output end of the polarization-maintaining fiber 3 to the polarization extinction ratio measurement module 4 and start the measurement."

[0067] In actual operation, after completing the filter mode treatment in the designated area of ​​the polarization-maintaining fiber 3 under test, and after removing the coating and cutting the end of the output end of the polarization-maintaining fiber 3 under test, the output end of the polarization-maintaining fiber 3 under test can be connected to the polarization extinction ratio tester, so that the light source 1, the polarization-maintaining fiber 3 under test, the polarization-maintaining fusion splicer and the polarization extinction ratio tester can form a complete measurement system.

[0068] After the incoherent linearly polarized light source is activated, the linearly polarized light emitted by it can be transmitted along its output arm 11 and the polarization-maintaining fiber 3 to the polarization extinction ratio tester. The polarization extinction ratio tester can detect the intensity distribution of linearly polarized light in different directions and calculate the extinction ratio.

[0069] It should be noted that, based on the above measurement system, this measurement method can measure the extinction ratio of polarization-maintaining optical fibers of various sizes.

[0070] For example, in one measurement experiment, light source 1 used an incoherent linearly polarized light source with a wavelength of 1064nm. The polarization extinction ratio of light source 1 was 28dB, while the corresponding standard single-mode polarization-maintaining fiber had a size of 6 / 125μm (the size combination of the core and cladding). At this time, the corresponding polarization-maintaining fiber 3 to be tested included three sizes: 10 / 125µm, 20 / 400µm, and 25 / 400µm.

[0071] In actual measurements, each type of polarization-maintaining fiber under test can be measured three times. The final measurement results are as follows: When the size of the polarization-maintaining fiber 3 under test is 10 / 125µm, the extinction ratio measurements of the three tests are 25.6dB, 25.2dB and 25.5dB, respectively. When the size of the polarization-maintaining fiber 3 under test is 20 / 400µm, the extinction ratio measurements of the three tests are 20.2dB, 20.4dB and 20.2dB, respectively. When the size of the polarization-maintaining fiber 3 under test is 25 / 400µm, the extinction ratio measurements for the three tests are 16.6dB, 16.4dB, and 16.3dB, respectively.

[0072] Based on the above experimental results, it can be found that, based on the above measurement system and combined with the measurement method, the measurement error fluctuation of the extinction ratio of polarization-maintaining fiber of any size and model is less than 0.5dB. The measurement operation is simple and the measurement results are accurate.

[0073] In summary, this invention reduces the deteriorating impact of cladding laser and mode coupling on extinction ratio testing by stripping the coating layer and applying a high-refractive-index filter to a designated area on the polarization-maintaining fiber 3 under test. Furthermore, leveraging the high stability of the incoherent linearly polarized light source ensures that the extinction ratio of the input linearly polarized light does not deteriorate with distance transmission. Based on this, the polarization-maintaining fusion splicer's alignment function is used to maintain the slow-axis output of the linearly polarized light, achieving rapid and accurate measurement of the extinction ratio of polarization-maintaining fibers of various sizes. The measurement results are closer to the actual performance in polarization-maintaining fiber applications.

[0074] Therefore, the measurement system provided by this invention has a simple structure and is easy to operate. Combined with the corresponding measurement method, it also has the advantages of minimal human error and high reliability.

[0075] In the description of this application, it should be noted that the terms "upper" and "lower," etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0076] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0077] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A polarization-maintaining fiber extinction ratio measurement system, characterized in that, include: A light source, the wavelength of which is the same as the operating wavelength of the polarization-maintaining fiber under test; A polarization-maintaining fusion splice module is disposed between the output end of the light source and the input end of the polarization-maintaining fiber under test, and is used to connect the output end of the light source and the input end of the polarization-maintaining fiber under test. as well as The polarization extinction ratio measurement module is located on the side where the output end of the polarization-maintaining fiber under test is located, and its input end is connected to the output end of the polarization-maintaining fiber under test. It is used to measure the extinction ratio of the polarization-maintaining fiber under test. Among them, a processing section is provided on the polarization-maintaining fiber under test near its output end. The processing section is used to reduce the influence of cladding light on the extinction ratio measurement.

2. The polarization-maintaining fiber extinction ratio measurement system according to claim 1, characterized in that, The light source is an incoherent linearly polarized light source, which is used to emit linearly polarized light with constant power as the optical signal, and the polarization extinction ratio of the linearly polarized light is greater than or equal to 25dB.

3. The polarization-maintaining fiber extinction ratio measurement system according to claim 2, characterized in that, The output arm of the incoherent linearly polarized light source is a standard single-mode polarization-maintaining fiber, and the core and cladding dimensions of the standard single-mode polarization-maintaining fiber are smaller than or equal to the core and cladding dimensions of the polarization-maintaining fiber under test.

4. The polarization-maintaining fiber extinction ratio measurement system according to claim 1, characterized in that, The center wavelength of the light source is: The first wavelength is used in measurements where the polarization-maintaining fiber under test is ytterbium-doped and uses related passive matching fibers; or The second wavelength is used for measurements where the polarization-maintaining fiber under test is ytterbium-doped and uses related passive matching fibers; or The third wavelength is used for measurements of polarization-maintaining fibers that are thulium-doped or thulium-holmium co-doped and related passive matching fibers.

5. The polarization-maintaining fiber extinction ratio measurement system according to claim 1, characterized in that, The processing section is a coating removal section, on which a high-refractive-index filter layer is coated.

6. The polarization-maintaining fiber extinction ratio measurement system according to claim 1, characterized in that, The polarization-maintaining fusion splicing module is a polarization-maintaining fusion splicer, which includes: The identification module is used to identify the type of polarization-maintaining fiber under test; Alignment module, used to align the slow and fast axes of polarization-maintaining fiber; and Fusion splicing module, used for splicing polarization-maintaining optical fibers.

7. A method for measuring the extinction ratio of polarization-maintaining optical fiber, characterized in that, The polarization-maintaining fiber extinction ratio measurement system as described in any one of claims 1-6 includes the following steps: The output end of the light source and the input end of the polarization-maintaining fiber under test are pre-processed. Align the output end of the light source with the input end of the polarization-maintaining fiber under test, and then fusion splice them together; Secondary preprocessing is performed on the area where the output end of the polarization-maintaining fiber under test is located. Connect the output end of the polarization-maintaining fiber under test to the polarization extinction ratio measurement module, and start the measurement.

8. The method for measuring the extinction ratio of polarization-maintaining optical fiber according to claim 7, characterized in that, The first preprocessing includes: Remove the coating from the output end of the light source and cut the output end of the light source at the specified cutting angle; Remove the coating from the input end of the polarization-maintaining fiber under test, and cut the input end of the fiber at the specified cutting angle.

9. The method for measuring the extinction ratio of polarization-maintaining optical fiber according to claim 7, characterized in that, The secondary preprocessing includes: The coating layer in a designated area on the polarization-maintaining fiber to be tested is stripped to form a coating stripping section. High-refractive-index adhesive is uniformly applied to the stripping section of the coating layer to achieve filter mold treatment; Remove the coating from the output end of the polarization-maintaining fiber under test, and cut the output end of the polarization-maintaining fiber under test at the specified cutting angle.

10. The method for measuring the extinction ratio of polarization-maintaining optical fiber according to claim 7, characterized in that, The output end of the alignment light source is connected to the input end of the polarization-maintaining fiber under test, and then fused together, including: Adjust the distance between the output end of the light source and the input end of the polarization-maintaining fiber under test; Slow-axis alignment is performed between the output end of the light source and the input end of the polarization-maintaining fiber to achieve slow-axis light transmission of linearly polarized light. The output end of the light source is fused to the input end of the polarization-maintaining fiber under test; The distance between the output end of the light source and the input end of the polarization-maintaining fiber under test is less than 100 μm.

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