The Research On The Key Cell Technology Of High Power Ytterbium Doped Fiber Laser With All-fiber Structure

In recent years,with the developments of high power fiber laser,the key fiber laser components have been becoming the bottleneck in power growth.This paper focus on the high power pump coupling components?fiber combiner and GTWave?,high power output components?cladding power stripping and fiber end-cup?which attract little attention before.We made some improvements for the component designing through combining theory and experiment,and proposed some new key technology.At last,the 2kW single-mode all-fiber oscillation had been fabricated.In terms of pump coupling components,firstly the new technics in fiber combiners and developments of typical fiber combiners were introduced.We summarized the typical fibers combination technics in the fiber combiner fabrication.Then we manufactured the7×1combiner with the coupling efficiency of 79.6%,based on the glass tube tapering technic utilizing the new CO₂-laser heat-source LZM-100.The GTWave coupling is better than the combiner with respect to high power pump coupling.Therefore we attempt to find the solutions through theoretical research.And the multimode coupling theory had been proved by means of experiments.We stressed on the influence of pump mode on the laser efficiency,and the efficiency and temperature contrast of?N+1?type and?1+1?type by the theory.The calculation shows that the?N+1?type GTWave and high-order mode pump contribute to the growth of laser efficiency.We offered some reasonable suggestions for the GTWave designing.In terms of laser output components,as to the cladding power stripping,firstly we summarized the new developments of three cladding power stripping technics,and calculated the stripping effects of cladding laser in different refractive index environments,which becomes the theory basis of components designing.The cladding power stripping had been optimized,and been compared with the traditional technics.The experiments show that the optimized scheme brings the falling of 3⁴?in the 30W cladding power.At last,we proposed two new cladding power stripping technics by means of evanescent wave effects.As to the fiber end-cap,after introducing whose work principles and structures,we analyzed the influence of output laser divergence angle on end-cap designing.Meanwhile,by means of the calculation of coreless-fiber end-cap return-light,the theory implies that the output angle has no obvious effect on the cladding-laser return-light loss,but obvious effect on the core-laser return-light loss.We completed the splicing of end-cap and fiber and finished the demonstration of 1.08kW.And the experimental results show that the output laser is almost the same with the 400?m coreless fiber end-cap.Besides,the high power fiber splicing technic,thermal dissipating technic and safety monitoring system have been studied.Firstly we studied the quality detection methods of high power fiber splicing,and analyzed the thermal phenomenon on the fusion point,and summarized the common technic schemes.Then the thermal dissipating technics in high power fiber laser had been analyzed.And we proposed the new modularized water-cooling schemes.A complete safety monitoring system in the high power fiber laser had been built up.At last,we established the 2kW single-mode oscillating structure fiber laser based on those key technics,with maximum output power of 2.01kW,laser efficiency of 82.5%,andM²?28?1.39.There are no obvious Mode Instability and Stimulated Raman phenomenons.