Method for testing gain fiber laser of high-power fiber laser

Abstract

The invention relates to a high-power fiber laser gain fiber laser test method, and belongs to the technical field of fiber lasers. The test method comprises the following steps: step 1, winding a to-be-tested gain optical fiber on a water cooling plate, and leaving two ends of the gain optical fiber; 2, stripping two passive optical fiber ends reserved on a laser, and outer cladding layers and coating layers on two end heads of a gain optical fiber to be measured; 3, the passive optical fiber core and the inner cladding are respectively welded with the gain optical fiber core and the inner cladding to form a welded optical fiber; 4, mixing and stirring the low-refractive-index AB glue to form AB mixed glue, and eliminating bubbles in the AB mixed glue; and step 5, pouring the AB mixed glue into a welding groove on the welding disc after bubble elimination, fixing the welding optical fiber on the welding disc, and arranging a welding point on the welding optical fiber in the welding groove. The device is convenient to operate, improves the test efficiency, reduces the test cost, improves the water cooling effect, and reduces the danger caused by the explosion point of the optical fiber fusion point.

Description

Technical Field

[0001] The present invention relates to a method for testing the laser of a gain fiber of a high-power fiber laser, belonging to the technical field of fiber lasers. Background Art

[0002] A fiber laser is a laser with a rare-earth element-doped fiber as the gain fiber. It has a high electro-optical conversion efficiency and good beam quality, and is widely used in the laser processing industry. A high-power fiber laser generally consists of devices such as a pump source, a passive fiber, a gain fiber (active fiber), a beam combiner, a grating, and a QBH. The fiber laser needs to fuse the fibers of each device together to connect the optical path, realize the conversion of electricity to light, and output laser. The gain fiber is the most core device of a high-power fiber laser. Before manufacturing a fiber laser, it is particularly important to test the laser performance of the gain fiber. Due to the relatively high input and output powers of high-power lasers, when testing the gain fiber, phenomena such as fiber burning and explosion points are likely to occur. Therefore, an efficient and safe testing method is required for the test.

[0003] Existing methods for testing the laser of a gain fiber: First, coil the gain fiber around a water-cooled plate and fix it. Then, fuse the two ends of the gain fiber with two segments of passive fibers on the laser, and use a fiber coating machine to coat the fusion point to protect the fusion point. A heat-conducting glue is applied to the surface of the water-cooled plate, and water flows through the inside to cool the gain fiber. Then, a laser test is carried out to observe whether the laser output power can reach the expected value, so as to judge whether the laser performance of the gain fiber is qualified.

[0004] The limitations of existing laser testing technologies are as follows: 1. High cost: After fusing the fibers together, the fusion point in the middle needs to be coated. Currently, domestic or imported coating machines on the market cost more than a hundred thousand yuan, bringing a relatively large cost pressure. In addition, the coating machine cures through an ultraviolet lamp, which is harmful to the human eyes after long-term use. A large amount of heat-conducting glue needs to be applied to the surface of the water-cooled plate, which also increases the detection cost.

[0005] 2. Low efficiency: The coating machine has unstable factors, reducing the detection efficiency; 3. Low water-cooling effect and low safety: The gain fiber is coiled around a water-cooled plate with water flowing through it for water cooling, and the water-cooling effect is not good. When there is an abnormality at the fiber fusion point, during the laser test, the temperature of the fusion point rises abnormally, and the fusion point is prone to explosion points and fiber burning, with low safety. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for testing the laser of a gain fiber of a high-power fiber laser in view of the above-mentioned existing technologies, which is convenient to operate, improves the test efficiency, reduces the test cost, improves the water-cooling effect, and reduces the danger caused by explosion points of fiber fusion points.

[0007] The technical solution adopted by the present invention to solve the above problems is: a method for testing the laser of a gain fiber of a high-power fiber laser, and the testing method includes the following steps: Step 1: Coil and fix the gain fiber to be tested on a water-cooled plate, leaving both ends of the gain fiber; Step 2: Strip the outer cladding and coating of the two ends of the passive fiber left on the laser, and the outer cladding and coating of both ends of the gain fiber to be tested; Step 3: Splice the passive fiber core and inner cladding with the gain fiber core and inner cladding respectively to form a spliced fiber; Step 4: Mix and stir the low-refractive-index AB glue to form an AB mixed glue, and eliminate the bubbles in the AB mixed glue; Step 5: Pour the degassed AB mixed glue into the welding groove on the welding plate, fix the spliced fiber on the welding plate, and the splicing point on the spliced fiber is arranged in the welding groove, and heat the welding plate; Step 6: After the AB mixed glue is cured, the welding plate, the spliced fiber and the water-cooled plate are integrated; then immerse the integrated part in water for cooling; Step 7: Perform laser testing on the gain fiber to complete the laser testing of the gain fiber.

[0008] In Step 1, the gain fiber to be tested is pasted on the water-cooled plate through a high-temperature-resistant tape.

[0009] In Step 4, the refractive index of the low-refractive-index AB glue is less than 1.6, and the refractive index of the AB mixed glue is lower than the refractive index of the inner cladding of the gain fiber to be tested.

[0010] In Step 4, the bubbles in the AB mixed glue are eliminated by a defoaming centrifuge, and the elimination time is greater than 30 s.

[0011] In Step 5, the welding groove is opened in the center of the welding plate, and clamping grooves are symmetrically opened on both sides of the welding groove. The clamping grooves communicate with the welding groove. The gain fiber and the passive fiber are respectively arranged in the clamping grooves and fixed on the welding plate through a high-temperature-resistant tape.

[0012] A heating sheet is arranged at the bottom of the welding plate in Step 5, and the heating sheet heats the welding plate to cure the AB mixed glue.

[0013] The temperature of the heating sheet is 140°C - 160°C.

[0014] A temperature sensor is arranged below the welding plate in Step 5. The temperature sensor is signal-connected to the laser. The temperature sensor detects the temperature of the splicing point of the spliced fiber. When the temperature of the splicing point is abnormal, the laser makes an emergency stop reaction.

[0015] The temperature sensor is a patch temperature sensor.

[0016] Compared with the prior art, the advantages of the present invention are as follows: a method for testing the laser of a high-power fiber laser gain fiber 1. The fusion point of the fusion spliced optical fiber is fixed and protected by the cooperation of the fusion splicing tray and the AB mixed glue, eliminating the need for coating with a coater. The operation is simple, improving the efficiency and reducing the production cost. 2. Using a low-refractive heat-curing glue to replace the ultraviolet-curing glue, eliminating the harm caused by the ultraviolet lamp. 3. Changing the water-cooling method by directly immersing the one-piece in water, improving the water-cooling effect and reducing the risk of explosion at the fusion point of the fusion spliced optical fiber. 4. The fusion splicing tray is equipped with a temperature sensor, which can detect the temperature of the fusion point, and the laser will stop power supply immediately in case of abnormality. Description of the Drawings

[0017] Figure 1 It is the operation flow chart of a method for testing the laser of a high-power fiber laser gain fiber according to an embodiment of the present invention; Figure 2 It is the three-dimensional view of the laser; Figure 3 It is the cross-sectional view of the gain fiber; Figure 4 It is the fusion splicing schematic diagram of the gain fiber and the passive fiber; Figure 5 It is the schematic diagram of the gain fiber wound on the water-cooling plate; Figure 6 It is the schematic diagram of the fusion splicing tray; Figure 7 It is the schematic diagram of the one-piece; In the figure, 1 is the laser, 2 is the passive fiber, 3 is the gain fiber, 3.1 is the core, 3.2 is the inner cladding, 3.3 is the outer cladding, 3.4 is the coating layer, 3.5 is the end of the gain fiber, 4 is the water-cooling plate, 5 is the fusion splicing tray, 5.1 is the fusion splicing groove, 5.2 is the clamping groove, 6 is the patch temperature sensor, and 7 is the fusion point. Detailed Embodiment

[0018] The present invention will be further described in detail below in conjunction with the embodiments of the drawings.

[0019] As Figure 1 shown, a method for testing the laser of a high-power fiber laser gain fiber in this embodiment includes the following steps: Step 1: Wind the gain fiber 3 to be tested around the water-cooling plate 4, leaving both ends of the gain fiber 3, and then paste the gain fiber to be tested on the water-cooling plate with a high-temperature resistant tape, as Figure 5 shown.

[0020] Step 2: As shown in Figure 2 , strip the outer cladding, coating layer of the two ends of the passive optical fiber 2 left on the laser 1, and the outer cladding and coating layer of the two ends of the gain optical fiber 3 to be measured. As shown in Figure 3 , the gain optical fiber respectively includes a core 3.1, and an inner cladding 3.2, an outer cladding 3.3 and a coating layer 3.4 are sequentially arranged on the core 3.1 from inside to outside. The passive optical fiber structure is the same as that of the gain optical fiber.

[0021] Step 3: As shown in Figure 4 , splice the core of the passive optical fiber and the inner cladding with the core of the gain optical fiber and the inner cladding respectively to form a spliced optical fiber and complete the loop connection.

[0022] Step 4: Mix and stir the low-refractive-index AB glue to form an AB mixed glue, and the refractive index of the AB mixed glue is lower than that of the inner cladding of the gain optical fiber; then use a defoaming centrifuge to eliminate the bubbles in the AB mixed glue, and the elimination time is 40 s to avoid air bubble cavities after the AB mixed glue cures.

[0023] Step 5: As shown in Figure 6 , pour the defoamed AB mixed glue into the welding groove 5.1 on the welding plate 5. The welding groove 5.1 is opened at the center of the welding plate 5. Card slots 5.2 are symmetrically opened on both sides of the welding groove 5.1, and the card slots communicate with the welding groove. A heating sheet is provided at the bottom of the welding plate 5. Place the gain optical fiber and the 3 passive optical fibers 2 in the card slots 5.2 respectively, and place the splicing point 7 of the spliced optical fiber in the welding groove 5.1, and then fix the gain optical fiber and the passive optical fiber on the welding plate with a high-temperature resistant tape. After completion of the fixing, heat the heating sheet and heat the welding plate to cure the AB mixed glue.

[0024] Step 6: As shown in Figure 7 , after the AB mixed glue cures, make the welding plate, the spliced optical fiber and the water-cooled plate into an integral part; then directly immerse the integral part in a water basin filled with water for cooling.

[0025] Step 7: Perform a laser test on the gain optical fiber to complete the laser test of the gain optical fiber.

[0026] The refractive index of the low-refractive-index AB glue in the above Step 4 is less than 1.6.

[0027] The temperature of the above heating sheet is 150 °C.

[0028] A patch temperature sensor 6 is provided below the splice tray in step five. The temperature sensor 6 is signal-connected to the laser 1. The patch temperature sensor 6 detects the temperature of the fusion point 7 of the spliced optical fiber. If there is an abnormality at the fusion point of the spliced optical fiber, the temperature of the fusion point will increase significantly during the laser test. After the temperature sensor detects the abnormality, the laser makes an emergency stop reaction and cuts off the power supply in time. If there is an explosion point at the fusion point, since the integral part is immersed in water, the water plays an isolation role and provides protection.

[0029] In this application, the fusion point of the spliced optical fiber is arranged in the splice groove, and the fusion point is fixed to the splice tray by curing the AB mixed glue, which plays a role of fixing and protecting. There is no need to use a coater for coating. The operation of this application is simple, which improves the test efficiency and reduces the production cost. The splice tray, the spliced optical fiber and the water-cooling plate are directly immersed in water, which improves the water-cooling effect and reduces the danger brought by the explosion point of the fusion point of the spliced optical fiber; the splice tray is equipped with a temperature sensor, which can detect the temperature of the fusion point, and the laser makes an emergency stop and cuts off the power supply in case of abnormality.

[0030] In addition to the above embodiments, the present invention also includes other implementation manners. Any technical solutions formed by equivalent transformation or equivalent substitution shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for testing the laser of a high-power fiber laser gain fiber, characterized in that: The described test method includes the following steps: Step 1: Coil and fix the gain optical fiber to be tested on the water-cooled plate, leaving both ends of the gain optical fiber exposed; Step 2: Strip the outer cladding and coating of the two ends of the passive optical fiber left on the laser, and the outer cladding and coating of both ends of the gain optical fiber to be tested; Step 3: Fuse the core and inner cladding of the passive optical fiber with the core and inner cladding of the gain optical fiber respectively to form a fused optical fiber; Step 4: Mix and stir the low-refractive-index AB glue to form an AB mixed glue, and eliminate the bubbles in the AB mixed glue; Step 5: Pour the degassed AB mixed glue into the fusion groove on the fusion tray, fix the fused optical fiber on the fusion tray, and place the fusion point on the fused optical fiber in the fusion groove, and heat the fusion tray; Step 6: After the AB mixed glue cures, make the fusion tray, the fused optical fiber and the water-cooled plate into an integral part; then immerse the integral part in water for cooling; Step 7: Conduct a laser test on the gain optical fiber to complete the laser test of the gain optical fiber.

2. The high-power fiber laser gain fiber laser test method according to claim 1, characterized in that: In Step 1, the gain optical fiber to be tested is pasted on the water-cooled plate by a high-temperature resistant tape.

3. A high-power fiber laser gain fiber laser testing method according to claim 1, characterized in that: In Step 4, the refractive index of the low-refractive-index AB glue is less than 1.6, and the refractive index of the AB mixed glue is lower than the refractive index of the inner cladding of the gain optical fiber to be tested.

4. A method for testing the laser of a high-power fiber laser gain fiber according to claim 1, characterized in that: In Step 4, the bubbles in the AB mixed glue are eliminated by a defoaming centrifuge, and the elimination time is greater than 30 s.

5. A method for testing the laser of a high-power fiber laser gain fiber according to claim 1, characterized in that: In Step 5, the fusion groove is opened in the center of the fusion tray, card slots are symmetrically opened on both sides of the fusion groove, the card slots communicate with the fusion groove, the gain optical fiber and the passive optical fiber are respectively arranged in the card slots, and are fixed on the fusion tray by a high-temperature resistant tape.

6. A high-power fiber laser gain fiber laser testing method according to claim 1, characterized in that: A heating sheet is arranged at the bottom of the fusion tray in Step 5, and the heating sheet heats the fusion tray to cure the AB mixed glue.

7. A method for testing the laser of a high-power fiber laser gain fiber according to claim 6, characterized in that: The temperature of the heating sheet is 140°C - 160°C.

8. A high-power fiber laser gain fiber laser test method according to claim 1, characterized in that: A temperature sensor is arranged below the fusion tray in Step 5, the temperature sensor is signal-connected to the laser, the temperature sensor detects the temperature of the fusion point of the fused optical fiber, and when the temperature of the fusion point is abnormal, the laser makes an emergency stop reaction.

9. A high-power fiber laser gain fiber laser test method according to claim 8, characterized in that: The temperature sensor is a patch temperature sensor.

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