To overcome Yb lasing,a kilowatt-level 1535 nm fiber laser is utilized to in-band pump an Er:Yb co-doped fiber(EYDF)amplifier.The output power of a 301 W narrow-linewidth EYDF amplifier operating at 1585 nm,with 3 dB ...To overcome Yb lasing,a kilowatt-level 1535 nm fiber laser is utilized to in-band pump an Er:Yb co-doped fiber(EYDF)amplifier.The output power of a 301 W narrow-linewidth EYDF amplifier operating at 1585 nm,with 3 dB bandwidth of 150 pm and M^(2)<1.4,is experimentally demonstrated.To the best of our knowledge,it is the highest output power achieved in L-band narrow-linewidth fiber amplifiers with good beam quality.Theoretically,a new ion transition behavior among energy levels for in-band pumping EYDF is uncovered,and a spatial-mode-resolved nonlinearityassisted theoretical model is developed to understand its internal dynamics.Numerical simulations reveal that the reduction in slope efficiency is significantly related to excited-state absorption(ESA).ESA has a nonlinear hindering effect on power scaling.It can drastically lower the pump absorption and slope efficiency with increasing pump power for in-band pumped EYDF amplifiers.Meanwhile,optimized approaches are proposed to improve its power to the kilowatt level via in-band pumping.展开更多
基金supported by the National Natural Science Foundation of China(Nos.62122040,62075113 and 61875103)。
文摘To overcome Yb lasing,a kilowatt-level 1535 nm fiber laser is utilized to in-band pump an Er:Yb co-doped fiber(EYDF)amplifier.The output power of a 301 W narrow-linewidth EYDF amplifier operating at 1585 nm,with 3 dB bandwidth of 150 pm and M^(2)<1.4,is experimentally demonstrated.To the best of our knowledge,it is the highest output power achieved in L-band narrow-linewidth fiber amplifiers with good beam quality.Theoretically,a new ion transition behavior among energy levels for in-band pumping EYDF is uncovered,and a spatial-mode-resolved nonlinearityassisted theoretical model is developed to understand its internal dynamics.Numerical simulations reveal that the reduction in slope efficiency is significantly related to excited-state absorption(ESA).ESA has a nonlinear hindering effect on power scaling.It can drastically lower the pump absorption and slope efficiency with increasing pump power for in-band pumped EYDF amplifiers.Meanwhile,optimized approaches are proposed to improve its power to the kilowatt level via in-band pumping.
