Research On Key Components And System Technology Of High Power Fiber Laser

Medium and high-power fiber laser has a very broad application prospect in intelligent manufacturing field.At present,it has partially replaced other types of lasers and is applied in cutting,welding,cleaning,rust removal,drilling,3D printing and other manufacturing and processing fields.With the promotion of "Made in China 2025" strategic target,the development of domestic fiber laser is also accelerating.However,at present,medium and high-power fiber lasers are still heavily rely on imports,mainly due to the poor stability of domestic fiber lasers.Import dependence also leads to high intelligent manufacturing application cost of the technology,which slowdown its promotion.In order to improve the performance of domestic fiber lasers,this dissertation aims to development,improvement and optimization upstream optical fiber devices of fiber laser system,to provide solutions and technical support for improving the stability of domestic laser system.Stability of the fiber laser system is strong dependent on upstream components.Only after the performance of key components such as Laser Mirror Grating,Fiber Pump Combiner,Cladding Power Stripper,and Laser Output Caput are improved,can the complete laser system have better performance.First in this dissertation,the key components mentioned above are researched and developed.Then we do the further research on fiber laser system by building a single-mode kW level fiber laser and a multi-mode 10 kW level fiber laser system with the key components developed.We success to produce the high-power chirped fiber Laser Mirror Grating which power level for kilowatts,using a chirped phase mask and a pulsed excimer laser.The bandwidth of mirror grating is up to 2 nm,and the reflectivity is over 99.5%.The bandwidth of output coupling grating is up to 1nm,and the reflectivity is about 10%.The Fiber Pump Combiner is fabricated by means of tapering fiber bundle using hydrogen-oxygen flame.The high pumping coupling efficiency(99.8%)and the signal transmittance(> 95%)can be achieved under technical skill with matched fibers.The samples can be applied to fiber lasers with kilowatts or even higher power.In terms of Cladding Power Stripper technology,when the stripping power is less than 40 W,it is relatively simple to use the high refractive index dielectric cladding power stripper technique.When the stripping power is higher,reaching hundreds of watts,it needs to use the surface etching cladding power stripper scheme.The technology of Laser Output Caput was studied,and the standard QBH interface output cable was made successfully using the technology of quartz expanding beam.Optical fiber produced by nLight company,self-made Laser Mirror Grating,(18+1)×1 Pump Combiner,surface etching Cladding Power Stripper,QBH Laser Output Cable and other key devices were used to build a kW level laser platform for experimental research,and the laser output power obtained was 1050 W.Finally,6sets of 1.45 kW single-mode laser modules were combined with self-made fiber Laser Power Combiner to obtain 8.7 kW total output power.