The Research On Cladding Power Stripper In Fiber Laser

As the rapid development of fiber laser,we require increasingly higher performance of Cladding Power Stripper(CPS)when stripping off useless cladding light.Index-matching glue is traditionally used to treat double-cladding fiber and produce CPS,while texturing is widely adopted in the manufacturing CPS.In this paper,we collaborate the mentioned methods to treat double-cladding fiber,and get unpackaged CPS naked fiber.Moreover,we design the CPS heat sink using So lid works CAD and simulate the corresponding thermal effect via Comsol.Finally,we apply the integral CPS into the fiber laser system and test.Our main contributions are listed as follows:Treat 20/400 double-cladding fiber with different speed of cladded texturing.After the micro-observation of the texturing surface,texturing and applying with index-matching glue,and access the treated optical fiber to LD laser system as well as fiber laser system to conduct the pre-test.The micro-observation indicated that the texturing effect is even,and there is no observation of optical fiber fracture.LD laser pre-experiment showed that the corresponding extinction ratio of cladding light of the treated optical fiber are 12.22-20.OdB respectively.Specifically,the first experimental unit meltdown under the stripping power of 90W.We chose the second experimental unit to test and get the result that the uniformity of optical stripping is good with the loss of fiber core signal around 0.001dB.The results demonstrate that using both texturing and index-matching glue to treat the double-cladding fiber is able to get satisfactory CPS naked fiber.Comprehensively considering the size of unpackaged CPS naked fiber and the framework of fiber laser air-cooling plate and water-cooling plate,we design the CPS heat sink via CAD.After verifying the boundary conditions,solving the equations and parameters such as material attributes,we imported the model into Comsol and used finite element meshdividing to do the simulation.Under steady working condition,the results indicate that:when the stripping power is 150W and under water cooling,the maximal temperature of CPS is 335K if the material of heat sink is Ferrum,while the temperature is 322K if the material of heat sink is 6063 Aluminum;when the stripping power is 100W,the material is 606 Aluminum and under air cooling,the maximal temperature of CPS is 330K and 345K respectively under the structure with fin surfaces and without fin surfaces.Generally,the tolerable maximal temperature of double-cladding fiber coating thereon and index-matching glue is around 333.5K,thus,the simulation results verify the structure of heat sink and confirm the heat sink material is 6063 Aluminum alloy.Merging the standard packaged CPS into 1000W continues fiber laser and 500W pulse fiber laser respectively,the testing results show that the insertion loss of CPS is 0.001dB and 0-0.001dB,the extinction ratio of cladding light is 19.12dB and 19.35dB,the reverse loss is 19.88dB and 20.05dB respectively in the different lasers.We adjusted the parameters based on the above results and optimized the CPS heat sink via adjusted simulation model.Through the increase of radiating area of the bottom surface of heat sink,the results indicated that the temperature of CPS decreased by 7 to 10 C under the stripping power of 150W.When the maximum stabilized operating temperature of heat sink is 333.5K,the stripping power is greater than 350W.Therefore,the packaged CPS is suitable for Kilowatt class Commercial Fiber Laser,the adjusted model is also instructive for the further optimization of CPS heat sink.