Manufacturing method of mode field adapter with high stripping ratio

Abstract

The invention belongs to the technical field of mode field adapter manufacturing, and discloses a high-stripping-ratio mode field adapter manufacturing method which comprises the following steps: providing a to-be-packaged optical fiber formed by at least performing cladding stripping, tapering and welding on an optical fiber I and an optical fiber II; a to-be-packaged optical fiber is placed in a groove-shaped shell provided with positioning pieces, the two positioning pieces are located at the two ends of the groove-shaped shell respectively, positioning grooves distributed in the axial direction are formed in the positioning pieces, and the two ends of the to-be-packaged optical fiber are placed in the positioning grooves of the positioning pieces respectively and covered and fixed by first glue; and the to-be-packaged optical fiber between the two positioning pieces is encapsulated by using second glue of which the refractive index is greater than the refractive index of the optical fiber cladding. According to the optical fiber mode field adapter, the packaging difficulty is reduced, the effect of cleanly stripping the cladding light is achieved, and the manufacturing time of the optical fiber mode field adapter with the cladding power stripping function is shortened.

Description

Technical Field

[0001] The invention belongs to the technical field of mode field adapter manufacturing, and in particular relates to a method for manufacturing a high stripping ratio mode field adapter. Background Art

[0002] The reverse mode field adapter (MFA) is one of the core components in the fiber laser. Its function is to reduce the fusion loss between the output fiber of the red light semiconductor laser (4 / 125, 7 / 125, 10 / 130 and other small core diameter and large NA fibers) and the passive fiber (14 / 250, 20 / 400 and other large core diameter and small NA fibers) to ensure a high pass rate of the red light. At the same time, a large amount of the pump light output by the front stage is still not absorbed after being absorbed by the active fiber (YDF) and injected into the back stage through the high reflective grating. If it is not processed, it will cause the back stage fiber device or the red light semiconductor laser to malfunction and burn. Therefore, if Figure 1 As shown, a cladding light stripper (CPS) is often set in front of the reverse MFA (reverse mode field adapter) to strip out this part of the pump light, so that the return light power transmitted to the red light semiconductor laser is ≤50 mw, which is a necessary condition for the long-term normal operation of the red light LD. This solution requires multiple devices such as MFA (reverse mode field adapter) and CPS (cladding light stripper) between the red light LD and HR (high reflection grating), and each device needs to be fused, which affects the red light insertion loss and reduces production efficiency. In order to facilitate the understanding of the English abbreviations of relevant technical terms in the prior art, the English interpretations of the relevant terms are: MPC is a fiber combiner, QBH is a type of laser output head, OC is a low reflection grating, HR is a high reflection grating, SMF is a single-mode fiber, MFA is a reverse mode field adapter, and CPS is a cladding light stripper.

[0003] Most existing solutions integrate red light LD-reverse MFA-CPS-HR, such as Figure 2 As shown, the number of welding points is reduced, the material cost is lowered, and the laser is made more compact. However, while the MFA-CPS integrated device is miniaturized, it also has obvious disadvantages: ① It is more difficult to manufacture; ② If it is burned or broken, it cannot be replaced and can only be remade. Therefore, the long-term reliability of the MFA-CPS integrated device is crucial.

[0004] For the MFA-CPS integrated device, the maximum pump light power injected through the passive optical fiber must be 100w, and the return light power transmitted to the red semiconductor laser must be ≤50mw. The manufacturing method of this type of fiber mode field adapter with cladding power stripping function is currently mostly through cladding stripping, taper, fusion, corrosion and glue fixation in the quartz tube. The cladding surface after corrosion changes from the original smooth plane to uneven pits, which does not meet the total reflection condition of cladding light transmission. The cladding light is scattered into space, so that after the 100w pump light passes through the MFA (reverse mode field adapter) and CPS (cladding light stripper) integrated device, the cladding light power output at one end of the red LD optical fiber is ≤50mw, ensuring the long-term stable operation of the red LD. However, this process method also has the following disadvantages: (1) In order to meet the high stripping ratio requirements (eg ≥ 33 dB), the existing fiber mode field adapter with cladding power stripping function takes a long time to manufacture, the process is complicated, and the mechanical strength of the optical fiber is reduced after corrosion and roughening.

[0005] (2) The stripped cladding light scatters into space, causing the temperature of the entire metal packaging slot shell to rise sharply, posing a potential threat to the long-term stability of the laser.

[0006] (3) MFA (reverse mode field adapter) and CPS (cladding light stripper) are straightened and suspended in the glass tube and fixed with UV glue. During the process of inserting into the glass tube, the optical fiber is easy to contact with the glass tube, causing the surface of the bare fiber to become dirty. After the light passes through, a large amount of heat accumulates in the dirty area, causing the device to burn. At the same time, high-frequency vibration when the product passes over speed bumps during transportation, mechanical shock during handling, and stress release of glue at both ends after long-term use may all cause the optical fiber to break, paralyzing the laser system. Summary of the invention

[0007] In view of this, an object of the present invention is to provide a method for manufacturing a mode field adapter with a high stripping ratio, so as to solve the problems that the existing mode field adapter manufacturing process is complicated and the waste heat generated has a great impact on the overall performance.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions: A method for manufacturing a high stripping ratio mode field adapter comprises the following steps: Providing an optical fiber to be packaged which is formed by at least stripping the cladding, tapering and fusion splicing the optical fiber 1 and the optical fiber 2; The optical fiber to be packaged is placed in a slot-shaped housing provided with positioning members, wherein the two positioning members are respectively located at two ends of the slot-shaped housing, and the positioning members are provided with positioning grooves distributed along the axial direction, and the two ends of the optical fiber to be packaged are respectively placed in the positioning groove of one positioning member and are covered and fixed by the first glue; The optical fiber to be packaged between the two positioning members is potted with a second glue having a refractive index greater than that of the optical fiber cladding.

[0009] In a possible implementation, the optical fiber to be packaged includes two coating layer segments and a bare fiber segment located between the two coating layer segments, and the relationship between the coating layer segment and the bare fiber segment of the optical fiber to be packaged placed on the positioning piece satisfies: A / B>1 / 2, wherein A is the length of the bare fiber segment, and B is the length of the coating layer segment.

[0010] In a possible implementation, the length of the coating layer section and the bare fiber section of the optical fiber to be packaged placed on the positioning member are equal.

[0011] In a possible implementation, the step of placing the optical fiber to be packaged into a slot-shaped housing provided with positioning members, the two positioning members are respectively located at two ends of the slot-shaped housing, and the two ends of the optical fiber to be packaged are respectively placed in the positioning groove of one positioning member and are covered and fixed by the first glue, including the following method: Clean and disinfect the slotted housing and positioning parts; Fix the two positioning pieces at the two ends of the grooved housing respectively by using the third glue, and allow the third glue to cure; The two ends of the optical fiber to be packaged are straightened and placed on the positioning piece. The optical fiber to be packaged on the positioning piece includes a coating layer section and a bare fiber section. Then, a first glue with a low refractive index is used to cover the optical fiber to be packaged on the fixed positioning piece, and then the first glue is cured.

[0012] In a possible implementation, the cross-section of the groove-shaped shell is a C-shaped structure, the cross-section of the positioning member is a semicircular structure, and the positioning member is lower than the top end surface of the groove-shaped shell.

[0013] In a possible implementation, the groove-shaped housing is made of glass, and the positioning member is made of quartz.

[0014] In a possible implementation, the step provides an optical fiber to be packaged formed by at least stripping the cladding of the optical fiber 1 and the optical fiber 2, tapering and fusion splicing, including the following method: Use a stripper to strip a section of the outer cladding of optical fiber 1 near the middle of the mode field adapter, and at the same time strip the outer cladding of one end of optical fiber 2 near the middle of the mode field adapter; The middle section of optical fiber 1 is tapered by a tapering machine so that the diameter of the small diameter end of the middle section of optical fiber 1 after tapering is consistent with the bare fiber diameter of optical fiber 2; Cut the small diameter end of the middle section of the optical fiber 1 after taper and the adjacent end of the optical fiber 2 flat, and the cutting angle is required to be ≤0.5°; The cut optical fiber 1 and optical fiber 2 are fused together by a fiber fusion splicer, and the fusion point is heated. The fusion loss is detected during the heating process. When the fusion loss is less than 0.2dB, the heating is stopped and the encapsulated optical fiber is completed.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The method for making a high stripping ratio mode field adapter of the present invention, through the shell structure and packaging method of the mode field adapter, does not need to consider the problems of improper operation of personnel during the glass tube insertion process, electrostatic adsorption causing dirty bare fibers and heat accumulation during use, thereby reducing the difficulty of packaging; the MFA is centrally potted in a high-refractive index glue, and the optical fiber is not corroded, which can also play the role of cleanly stripping the cladding light, reducing the production time of the optical fiber mode field adapter with cladding power stripping function, and improving the mechanical strength (tensile and vibration resistance) and long-term reliability of the MFA-CPS integrated device. At the same time, the cladding light can be completely absorbed by the second glue with a high refractive index, rather than being scattered into space, reducing the impact of this part of waste heat on the performance of the whole machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the first existing laser optical path device; Figure 2 It is a structural schematic diagram of the existing second type of laser optical path device; Figure 3 A flowchart of a method for making a high stripping ratio mode field adapter; Figure 4 A three-dimensional view of a packaging structure of a mode field adapter for a method of manufacturing a mode field adapter with a high stripping ratio; Figure 5 A top view of a mode field adapter for a method of manufacturing a mode field adapter with a high stripping ratio; Figure 6 A cross-sectional view of a mode field adapter showing a method for manufacturing a mode field adapter with a high stripping ratio; Figure 7 It is a structural schematic diagram of the mode field adapter of comparative example 1; Figure 8 It is a structural schematic diagram of the mode field adapter of comparative example 2; Fig. 9 Schematic diagram of the stripping ratio test principle.

[0017] In the figure: 11-first low refractive index UV glue 1; 12-first passive optical fiber coating layer; 13-first passive optical fiber bare fiber; 14-first mode field adapter transition zone; 15-first mode field adapter waist zone; 16-red light LD output bare fiber hairing zone; 17-first red light LD output bare fiber; 18-first red light LD output optical fiber coating layer; 19-second low refractive index UV glue 1; 110-mode field adapter and cladding light stripper; 111-first quartz tube; 21-first low-refractive index UV glue 2; 22-second passive optical fiber coating layer; 23-second passive optical fiber bare fiber; 24-cladding light first section corrosion zone; 25-cladding light second section corrosion zone; 26-second mode field adapter transition zone; 27-second mode field adapter waist zone; 28-second red light LD output optical fiber bare fiber; 29-second red light LD output optical fiber coating layer; 210-second low-refractive index UV glue 2; 211-cladding light corrosion zone; 212-second quartz tube; 1-groove-shaped housing; 2-passive optical fiber coating; 3-positioning piece; 4-passive optical fiber bare fiber; 5-mode field adapter transition area; 6-red light LD output fiber bare fiber; 7-red light LD output fiber coating; 8-first low refractive index UV glue fixing area; 9-high refractive index UV glue fixing area; 10-second low refractive index UV glue fixing area. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with specific implementation methods.

[0019] In order to facilitate the understanding of the English abbreviations of the relevant technical terms of this application, the English explanations of the relevant terms are: MPC is a fiber beam combiner, QBH is a type of laser output head, OC is a low-reflection grating, HR is a high-reflection grating, SMF is a single-mode optical fiber, MFA is a reverse mode field adapter, and CPS is a cladding light stripper.

[0020] Please refer to Figure 3-Figure 6 As shown, a method for manufacturing a high stripping ratio mode field adapter according to an embodiment of the present application comprises the following steps: Step S100: providing an optical fiber to be packaged which is formed by at least stripping the cladding, tapering and fusion splicing an optical fiber 1 and an optical fiber 2.

[0021] In this step, the optical fiber 1 and the optical fiber 2 are stripped of cladding and taper, and then fusion spliced ​​to form the optical fiber to be packaged, which can be used as the adapter optical fiber of the mode field adapter. In other methods, the optical fiber to be packaged can also be prepared by adding other processes besides stripping of cladding, taper and fusion splicing, such as heating after fusion splicing to reduce fusion loss.

[0022] Step S200: Place the optical fiber to be packaged into a slotted housing provided with positioning pieces, wherein two positioning pieces are respectively located at two ends of the slotted housing, and the positioning pieces are provided with positioning grooves distributed along the axial direction, and the two ends of the optical fiber to be packaged are respectively placed in the positioning groove of a positioning piece and are covered and fixed by the first glue.

[0023] In this step, the slot-shaped shell is an open structure, which is convenient for packaging operations. It can be a U-shaped structure or a square slot structure, and there is no limitation. This structure can facilitate the installation and fixation of the positioning parts, and also facilitate the formation of a fillable filling area between the positioning parts. Two positioning parts are provided and are respectively located at the two ends of the slot-shaped shell. The positioning grooves thereon can facilitate the accurate placement of the two ends of the optical fiber to be packaged and cover and fix them with the first glue. By fixing the MFA with an open shell structure and positioning parts, there is no need to consider problems such as improper operation of personnel during the glass tube insertion process, electrostatic adsorption causing the bare fiber to be dirty and causing heat accumulation during use, thereby reducing the difficulty of packaging. Specifically, the first glue uses low-refractive glue, which can reduce light loss and can play a role in fixing the two ends of the optical fiber to be packaged.

[0024] Step S300: using a second glue having a refractive index greater than the refractive index of the optical fiber cladding to potting the optical fiber to be packaged between the two positioning members.

[0025] In this step, the second glue is a high-refractive glue, and its refractive index is higher than the refractive index of the optical fiber cladding, which can also play the role of stripping the cladding light, thereby reducing the production time of the optical fiber mode field adapter with cladding power stripping function, and improving the mechanical strength (tensile and vibration resistance) and long-term reliability of the MFA-CPS integrated device. Through such a grooved shell structure, the encapsulation of the second glue is also more convenient. The high-refractive index second glue can also destroy the total reflection transmission condition of the cladding light, and the pump light will be completely absorbed by the high-refractive glue between the two positioning parts. The second glue can be a UV glue with a refractive index of 1.56 after UV curing, or a glue that meets the following conditions can replace the glue: no obvious absorption peak in the visible light and near-infrared bands, low stress after curing, good adhesion to glass materials, a refractive index of 1.56, and no significant change in glue performance after high-temperature and high-humidity storage, low-temperature storage, and high-low temperature impact.

[0026] Through the above technical solutions, the shell structure and packaging method of the mode field adapter do not need to consider problems such as improper operation of personnel during the glass tube, electrostatic adsorption causing bare fiber to be dirty and causing heat accumulation during use, which reduces the difficulty of packaging; the MFA is centrally potted in high-refractive index glue, and the optical fiber is not corroded, which can also play the role of cleanly stripping the cladding light, reducing the production time of the optical fiber mode field adapter with cladding power stripping function, and improving the mechanical strength (tensile and vibration resistance) and long-term reliability of the MFA-CPS integrated device. At the same time, the cladding light can be completely absorbed by the second glue with a high refractive index instead of being scattered into space, reducing the impact of this part of waste heat on the performance of the whole machine.

[0027] In one embodiment, the optical fiber to be packaged includes two coating layer segments and a bare fiber segment located between the two coating layer segments, and the relationship between the coating layer segment and the bare fiber segment of the optical fiber to be packaged placed on the positioning piece satisfies: A / B>1 / 2, wherein A is the length of the bare fiber segment, and B is the length of the coating layer segment.

[0028] In this way, the optical fiber to be packaged placed on the positioning piece can include a bare fiber segment. By extending the length of the bare fiber segment onto the positioning piece, the optical fiber coating can maintain a safe distance from the area sealed with the high refractive index second glue. This safe distance can avoid the influence of waste heat absorbed by the second glue on the optical fiber coating.

[0029] Preferably, the length of the coating layer section of the optical fiber to be packaged placed on the positioning member is equal to the length of the bare fiber section. Half bare fiber and half coating layer are more convenient for manufacturing and positioning length.

[0030] In an embodiment of the present application, step S200 includes the following method: Step S210: Clean and disinfect the grooved housing and the positioning parts.

[0031] In this step, the grooved housing and the positioning parts are cleaned and disinfected to improve the cleanliness of the grooved housing and the positioning parts, and to prevent stains from affecting light transmission. Specifically, the grooved housing and the positioning parts are placed in an ultrasonic cleaner filled with alcohol, and are taken out and blown dry after cleaning for 5 minutes.

[0032] Step S220: fix the two positioning members at the two ends of the groove-shaped housing respectively by using the third glue, and solidify the third glue.

[0033] In this step, the positioning piece and the groove-shaped shell are split structures. During production, it needs to be installed in the groove-shaped shell and fixed with a small amount of glue so that the positioning piece is stable in the groove-shaped shell. Specifically, the groove-shaped shell needs to be fixed before placement, for example, it can be placed on a fixed tooling that matches its size, and then a small amount of UV glue is applied to the bottom side of the positioning piece. Use tweezers to place the positioning piece at both ends of the groove-shaped shell, adjust the position so that the outer edge of the positioning piece is flush with the edge of the groove-shaped shell, and finally use ultraviolet light to irradiate the glue at both ends for 30 seconds so that the positioning piece is in close contact with the groove-shaped shell, so that the positioning piece can be installed.

[0034] Step S230: straighten both ends of the optical fiber to be packaged and place them on the positioning piece, the optical fiber to be packaged on the positioning piece includes a coating layer segment and a bare fiber segment, and then use a first glue with a low refractive index to cover the optical fiber to be packaged on the fixed positioning piece, and then cure the first glue.

[0035] In this step, the optical fibers at both ends of the optical fiber to be packaged are straightened and placed on two positioning pieces, half of which are optical fiber coating layers and half are bare fibers. Then, low-refractive-index UV glue is used to cover the optical fiber coating layer and bare fibers placed on the positioning pieces, and then the glue is irradiated with ultraviolet light for 30 seconds to firmly fix the optical fiber to be packaged.

[0036] In a preferred implementation structure of the trough shell and the positioning member, the cross-section of the trough shell is a C-shaped structure, the cross-section of the positioning member is a semicircular structure, and the positioning member is lower than the top end surface of the trough shell.

[0037] The C-shaped grooved housing can facilitate the packaging operation and the quick placement of the semicircular positioning piece with the same shape. At the same time, after being placed and fixed, the top end face or edge of the grooved structure is lower than the structural design, so that the first glue can be filled at a certain height to cover and fix the optical fiber to be packaged after it is placed, and the structural design is more reasonable. The positioning piece has a longer length in the axial direction, so that the area covered by the low-refractive index first glue can be more fully covered, so that the optical fiber coating layer and the high-refractive index second glue potting area maintain a safe distance.

[0038] In other embodiments, the grooved housing may also adopt other structures, such as a V-shape, and the corresponding positioning member may also adopt a structure with a matching triangular cross-section, which may also facilitate packaging operations.

[0039] Specifically, the groove-shaped housing is made of glass, and the positioning piece is made of quartz. Compared with the metal housing, the glass material has a lower temperature rise coefficient, lower cost, and lighter weight.

[0040] In one embodiment, step S100 includes the following method: Step S110: Use a stripper to strip a section of the outer cladding of the optical fiber 1 near the middle of the mode field adapter, and at the same time strip the outer cladding of one end of the optical fiber 2 near the middle of the mode field adapter; Step S120: taper the middle section of optical fiber 1 by a taper machine so that the diameter of the small diameter end of the middle section of optical fiber 1 after tapering is consistent with the bare fiber diameter of optical fiber 2; Step S130: Cutting the small diameter end of the middle section of the tapered optical fiber 1 and the adjacent end of the optical fiber 2 flat, with the cutting angle being required to be ≤0.5°; Step S140: The cut optical fiber 1 and optical fiber 2 are fused by an optical fiber fusion splicer, and the fusion point is heated. The fusion loss is detected during the heating process. When the fusion loss is less than 0.2 dB, the heating is stopped, and the encapsulated optical fiber is completed.

[0041] Through the above steps, an optical fiber to be packaged that can be used to make a mode field adapter can be obtained.

[0042] In order to better illustrate the effect and performance of a method for manufacturing a high stripping ratio mode field adapter according to an embodiment of the present application, the following comparative examples and embodiments are provided for comparative analysis: The core and cladding diameters of the red light output fiber are 4 μm and 125 μm respectively, and the core NA is 0.12; the core and cladding diameters of the passive optical fiber are 14 μm and 250 μm respectively, the core NA is 0.07, and the cladding NA is ≥ 0.46. The maximum pump light power injected through the passive optical fiber is 100 w, and the return light power transmitted to the red light semiconductor laser needs to be ≤ 50 mw.

[0043] Comparative Example 1: The following preparation method is used to prepare Figure 7 As shown, the method includes the following main steps: ① Use a middle section stripper to strip a section of the outer cladding near the middle of the 14 / 250 optical fiber, with a stripping length of no less than 15 cm; strip a section of the outer cladding near the end face of the 4 / 125 optical fiber.

[0044] ② Use a fusion taper machine to taper the middle section of the 14 / 250 optical fiber so that the diameter of the waist region 15 of the first mode field adapter after taper is 125 μm.

[0045] ③ Cut the 14 / 250 optical fiber after taper at the waist area 15 of the first mode field adapter, and cut the end face of the 4 / 125 optical fiber flat. The optical fiber cutting angle is required to be ≤0.5°; ④Use CO 2 After the fiber optic fusion splicer fuses the cut 14 / 250 and 4 / 125 optical fibers, the fusion point needs to be further heated to make the fusion loss less than 0.2dB. The specific heating method is: 2 Light is passed through the fiber fusion splicer, the output power is monitored by a power meter, and then the laser is turned on to heat the area near the melting point. The heating is stopped when the loss of the mode field adapter meets the preset value.

[0046] ⑤ Use glass frosting to corrode the cladding of the first mode field adapter transition area 14, the first mode field adapter waist area 15 and part of the red light LD output bare fiber area 16 for 15 minutes (stripping ratio ≥ 33 dB), and then use pure water to rinse the corrosive paste. The cladding surface after corrosion changes from the original smooth plane to uneven pits, which does not meet the total reflection conditions of cladding light transmission. The cladding light is scattered into space, so that after the 100w pump light passes through the MFA and CPS integrated device, the cladding light power output at one end of the red light LD fiber is ≤50mw, ensuring the long-term stable operation of the red light LD.

[0047] ⑥ Then use low-refractive index UV glue to irradiate with ultraviolet light for 30 seconds to straighten and suspend the first passive optical fiber coating 12, the first passive optical fiber bare fiber 13, the first mode field adapter transition zone 14, the first mode field adapter waist zone 15, the red light LD output bare fiber haired area 16, the first red light LD output bare fiber 17, and the first red light LD output optical fiber coating 18 in the first quartz tube 111.

[0048] The lengths of the above regions are shown in Table 1 below: Table 1

[0049] Combination Figure 7 As shown, the two ends of the optical fiber in the first quartz tube 111 are fixed by a first low-refractive index UV glue 11 and a second low-refractive index UV glue 19 respectively, and the corroded and roughened area corresponds to the mode field adapter and the cladding light stripper 110.

[0050] Comparative Example 2: The following preparation method is used to prepare Figure 8 As shown, the method includes the following main steps: ① Use a middle section stripper to strip a section of the outer cladding near the middle of the 14 / 250 optical fiber, with a stripping length of no less than 15 cm; strip a section of the outer cladding near the end face of the 4 / 125 optical fiber.

[0051] ② Use a fusion taper machine to taper the middle section of the 14 / 250 optical fiber so that the diameter of the waist region 27 of the second mode field adapter after tapering is 125 μm; ③ Cut the tapered 14 / 250 optical fiber flat at the waist area 27 of the second mode field adapter, and cut the 4 / 125 optical fiber flat. The cutting angle is required to be ≤0.5°; ④Use CO 2 After the fiber optic fusion splicer fuses the cut 14 / 250 and 4 / 125 optical fibers, the fusion point needs to be further heated to make the fusion loss less than 0.2dB. The specific heating method is: 2 Light is passed through the fiber fusion splicer, and the output power is monitored by a power meter. Then the laser is turned on to heat the area near the melting point. When the loss of the mode field adapter meets the preset value, the heating is stopped. ⑤ Use glass frosting to corrode the second-segment corrosion zone 25 of the cladding light for 2 h (to make its stripping ratio ≥33 dB), and corrode the first-segment corrosion zone 24 of the cladding light for 10 min (due to the deep extent of the second-segment corrosion zone 25 of the cladding light, a large amount of scattered return light is transmitted to the input stripping port while the cladding light is stripped by the second segment. The function of the first-segment corrosion zone 24 of the cladding light is to strip the return light and reduce the temperature of the input coating layer), and then use pure water to rinse the corrosion paste. The cladding surface after corrosion changes from the original smooth plane to uneven pits, which does not meet the total reflection condition of cladding light transmission. The cladding light is scattered into space, making the cladding light power output from one end of the red light LD optical fiber ≤50 mw, ensuring the long-term stable operation of the red light LD.

[0052] ⑥ Then use low-refractive index UV glue to irradiate with ultraviolet light for 30 seconds, and straighten the second passive optical fiber coating 22, the second passive optical fiber bare fiber 23, the cladding light first section corrosion zone 24, the cladding light second section corrosion zone 25, the second mode field adapter transition zone 26, the second mode field adapter waist zone 27, the second red light LD output optical fiber bare fiber 28, and the second red light LD output optical fiber coating 29 and fix them in the second quartz tube 212.

[0053] The lengths of the above regions are shown in Table 2 below: Table 2

[0054] Combination Figure 8 As shown, the two ends of the optical fiber in the second quartz tube 212 are fixed by the first low-refractive index UV glue 21 and the second low-refractive index UV glue 210 respectively, and the corroded area corresponds to the cladding light corroded area 211.

[0055] The packaging method of the present application is used to package the optical fibers to be packaged that have been fused in Comparative Example 1 and Comparative Example 2, respectively. The packaging method includes the following steps: Step 1: Place the slotted housing and positioning parts into an ultrasonic cleaner filled with alcohol, clean for 5 minutes, then take them out and blow dry.

[0056] Step 2: Place the slot-shaped shell on a fixed fixture that matches its size, apply a small amount of UV glue on the bottom side of the locating piece, use tweezers to place the locating piece on both ends of the slot-shaped shell, adjust the position so that the outer edge of the locating piece is flush with the edge of the slot-shaped shell, and finally use ultraviolet light to irradiate the glue on both ends for 30 seconds to make the locating piece in close contact with the slot-shaped shell.

[0057] The third step is to straighten the optical fibers (14 / 250, 4 / 125) at both ends of the optical fiber to be packaged and place them on two positioning pieces. Half of the positioning piece is the optical fiber coating layer and the other half is the bare fiber. Use low-refractive-index UV glue to cover the optical fiber coating layer and bare fiber placed on the positioning piece, and then irradiate the glue with ultraviolet light for 30 seconds to firmly fix the MFA.

[0058] The fourth step is to use glue with a refractive index greater than that of the optical fiber cladding to completely encapsulate the optical fiber between the two positioning pieces. The glue model is NOA61, and the refractive index after UV curing is 1.56.

[0059] In this way, the package structure can be combined with Figure 4-Figure 6 As shown, two positioning members 3 are fixed on the inner side of the slot-shaped shell, and the two positioning members 3 are lower than the top edge of the slot-shaped shell to facilitate glue covering to fix the two ends of the optical fiber to be packaged, one end of the optical fiber to be packaged includes a passive optical fiber coating layer 2 and a passive optical fiber bare fiber 4, and the other end includes a red light LD output fiber bare fiber 6 and a red light LD output fiber coating layer 7, between the passive optical fiber bare fiber 4 and the red light LD output fiber bare fiber 6 is a mode field adapter transition area 5, the space area between one positioning member 3 and the top edge of the slot-shaped shell 1 is a first low refractive index UV glue fixing area 8, the area between the two positioning members 3 is a high refractive index UV glue fixing area 9, and the space area between the other positioning member 3 and the top edge of the slot-shaped shell 1 is a second low refractive index UV glue fixing area 10.

[0060] When the laser is running, the pump light that is not absorbed by the YDF is transmitted to the MFA device through the passive optical fiber cladding. The high refractive index glue of the packaging structure destroys the total reflection transmission condition of the cladding light, and the pump light is completely absorbed by the high refractive index glue between the two positioning parts.

[0061] The packaging scheme is used to package the optical fibers to be packaged that have been fused in Comparative Example 1 and Comparative Example 2, respectively. That is, the above packaging method is used to replace step 5 and step 6 in Comparative Example 1 and Comparative Example 2. In this way, four schemes can be obtained, namely, Comparative Example 1, Comparative Example 2, and Example 1 and Example 2 packaged by the embodiment scheme of the present application. The stripping ratio, manufacturing time, and mechanical properties of these four MFA integrated CPS devices are compared (the stripping ratio test method is as follows Fig. 9 ), the comparison results are shown in Table 3. 50 samples of each type were made, and the mechanical properties were evaluated by the failure ratio of samples after vibration test (10-60 Hz, amplitude 0.5 mm, 48 h), high and low temperature shock (-40℃-85℃, temperature conversion time ≤3 min, shock 1000 times).

[0062] Table 3

[0063] From the comparison of the data in Table 3, it can be seen that Example 1 and Example 2 use a C-shaped open grooved housing and positioning parts to fix the MFA, so there is no need to consider problems such as improper operation of personnel during the glass tube insertion process, electrostatic adsorption causing the bare fiber to be dirty and causing heat accumulation during use, which reduces the difficulty of packaging. The MFA is centrally potted in a high-refractive index glue, and the optical fiber is not corroded, which can also play the role of cleanly stripping the cladding light, reducing the production time of the optical fiber mode field adapter with cladding power stripping function, and improving the mechanical strength (tensile and vibration resistance) and long-term reliability of the MFA-CPS integrated device. At the same time, compared with the existing solution, the cladding light of this solution is completely absorbed by the high-refractive index glue instead of being scattered into space, reducing the impact of this part of waste heat on the performance of the whole machine.

[0064] The above are only preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention, and the protection scope of the present invention should be based on the scope defined by the claims. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for manufacturing a high stripping ratio mode field adapter, characterized in that: The following steps are involved: Providing an optical fiber to be packaged which is formed by at least stripping the cladding, tapering and fusion splicing the optical fiber 1 and the optical fiber 2; The optical fiber to be packaged is placed in a slot-shaped housing provided with positioning members, wherein the two positioning members are respectively located at two ends of the slot-shaped housing, and the positioning members are provided with positioning grooves distributed along the axial direction, and the two ends of the optical fiber to be packaged are respectively placed in the positioning groove of one positioning member and are covered and fixed by the first glue; The optical fiber to be packaged between the two positioning members is potted with a second glue having a refractive index greater than that of the optical fiber cladding.

2. A method for manufacturing a high stripping ratio mode field adapter as claimed in claim 1, characterized in that: The optical fiber to be packaged includes two coating layer segments and a bare fiber segment located between the two coating layer segments. The relationship between the coating layer segment and the bare fiber segment of the optical fiber to be packaged placed on the positioning piece satisfies: A / B>1 / 2, wherein A is the length of the bare fiber segment and B is the length of the coating layer segment.

3. A method for manufacturing a high stripping ratio mode field adapter as claimed in claim 2, characterized in that: The length of the coating layer section and the bare fiber section of the optical fiber to be packaged placed on the positioning piece are equal.

4. A method for manufacturing a high stripping ratio mode field adapter as claimed in claim 1, characterized in that: The step of placing the optical fiber to be packaged into a slot-shaped housing provided with positioning members, wherein the two positioning members are respectively located at two ends of the slot-shaped housing, and the two ends of the optical fiber to be packaged are respectively placed in the positioning groove of one positioning member and are covered and fixed by the first glue, including the following method: Clean and disinfect the slotted housing and positioning parts; Fix the two positioning pieces at the two ends of the grooved housing respectively by using the third glue, and allow the third glue to cure; The two ends of the optical fiber to be packaged are straightened and placed on the positioning piece. The optical fiber to be packaged on the positioning piece includes a coating layer section and a bare fiber section. Then, a first glue with a low refractive index is used to cover the optical fiber to be packaged on the fixed positioning piece, and then the first glue is cured.

5. The method for manufacturing a high stripping ratio mode field adapter according to claim 1, characterized in that: The cross section of the groove-shaped shell is a C-shaped structure, the cross section of the positioning piece is a semicircular structure, and the positioning piece is lower than the top end surface of the groove-shaped shell.

6. A method for manufacturing a high stripping ratio mode field adapter as claimed in claim 1, characterized in that: The groove-shaped housing is made of glass, and the positioning piece is made of quartz.

7. A method for manufacturing a high stripping ratio mode field adapter as claimed in claim 1, characterized in that: The step provides an optical fiber to be packaged, which is formed by at least stripping the cladding of the optical fiber 1 and the optical fiber 2, tapering and fusion splicing, including the following method: Use a stripper to strip a section of the outer cladding of optical fiber 1 near the middle of the mode field adapter, and at the same time strip the outer cladding of one end of optical fiber 2 near the middle of the mode field adapter; The middle section of the optical fiber 1 is tapered by a tapering machine so that the diameter of the small diameter end of the middle section of the optical fiber 1 after tapering is consistent with the bare fiber diameter of the optical fiber 2; Cut the small diameter end of the middle section of the optical fiber 1 after taper and the adjacent end of the optical fiber 2 flat, and the cutting angle is required to be ≤0.5°; The cut optical fiber 1 and optical fiber 2 are fused together by a fiber fusion splicer, and the fusion point is heated. The fusion loss is detected during the heating process. When the fusion loss is less than 0.2dB, the heating is stopped and the encapsulated optical fiber is completed.

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