Stimulated Raman scattering in a double cladding optical fiber is studied with a continuous wave laser used as a pump source. Under various launch conditions, pump modes are differently excited. Considering the mode c...Stimulated Raman scattering in a double cladding optical fiber is studied with a continuous wave laser used as a pump source. Under various launch conditions, pump modes are differently excited. Considering the mode coupling effect among the pump modes, the evolution of the power in the Stokes modes is studied. The results show that the scattered waves （the Stokes waves） in the fiber core with 9%tm diameter and 0.14 NA could propagate predominantly in the fundamental mode of the fiber by carefully adjusting the pump light launching conditions.展开更多
Stimulated Raman scattering(SRS) effect is considered to be one of the main obstacles for power scaling in general-type fiber lasers. Different from previous techniques that aim at suppressing SRS, nonlinear fiber amp...Stimulated Raman scattering(SRS) effect is considered to be one of the main obstacles for power scaling in general-type fiber lasers. Different from previous techniques that aim at suppressing SRS, nonlinear fiber amplifier(NFA), which manipulates and employs the SRS for power scaling in rare-earth-doped fiber, is under intensive research in recent years.In this paper, the authors will present an all-round study on this new kind of high-power fiber amplifier. A theoretical model is proposed based on the rate equation and amplified spontaneous emission(ASE), with random noise taken into account. By numerical solving of the theoretical model, the power scaling potential, heat analysis and advantages in suppressing the undesired backscattering light are quantificationally analyzed for the first time. Then two different types of high-power NFAs are demonstrated individually. Firstly, a laser diode pumped NFA has reached kilowatt output power,and the results agree well with theoretical predictions. Secondly, a tandem-pumped NFA is proposed for the first time and validated experimentally, in which 1.5 kW output power has been achieved. The authors also briefly discuss several new issues relating to the complex nonlinear dynamics that occur in high-power NFAs, which might be interesting topics for future endeavors.展开更多
We report a 2 kW all-fiberized Raman fiber amplifier with efficient brightness enhancement based on the graded-index fiber.The maximum power output reaches up to 2.034 kW centered at 1130 nm,with a conversion efficien...We report a 2 kW all-fiberized Raman fiber amplifier with efficient brightness enhancement based on the graded-index fiber.The maximum power output reaches up to 2.034 kW centered at 1130 nm,with a conversion efficiency of 79.35%with respect to the injected pump power.To the best of our knowledge,this is the highest conversion efficiency obtained for any Raman laser system using graded-index fiber.An optimized fiber combiner adopting graded-index fiber as the pigtail fiber was fabricated,enabling the preservation of the seeding brightness in the core-pumped Raman fiber amplifier,and further enhancing the ultimate brightness of the output laser after amplification.At the maximum power output,the beam quality parameter M2 is 2.8,corresponding to a signal-to-pump brightness enhancement factor of 11.2.As far as we know,we obtain the highest brightness enhancement among Raman fiber lasers of over 100 W,and the best beam quality for graded-index Raman fiber lasers of over 150 W.展开更多
Employing the technique of symmetry reduction of analytic method, we solve the Ginzburg-Landau equation with varying nonlinear, dispersion, gain coefficients, and gain dispersion which originates from the limiting eff...Employing the technique of symmetry reduction of analytic method, we solve the Ginzburg-Landau equation with varying nonlinear, dispersion, gain coefficients, and gain dispersion which originates from the limiting effect of transition bandwidth in the realistic doped fibres. The parabolic asymptotic self-similar analytical solutions in gain medium of the normal GVD is found for the first time to our best knowledge. The evolution of pulse amplitude, strict linear phase chirp and effective temporal width are given with self-similarity results in longitudinal nonlinearity distribution and longitudinal gain fibre. These analytical solutions are in good agreement with the numerical simulations. Furthermore, we theoretically prove that pulse evolution has the characteristics of parabolic asymptotic self-similarity in doped ions dipole gain fibres.展开更多
在基于大模场面积的高功率光纤放大器中,随着放大激光功率的提升而出现的高阶模激发现象,将会导致放大激光的光束质量严重下降。以光纤模式的弯曲损耗特性为基础,研究了光纤弯曲半径对高功率全光纤放大器高阶模激发阈值特性的影响。搭...在基于大模场面积的高功率光纤放大器中,随着放大激光功率的提升而出现的高阶模激发现象,将会导致放大激光的光束质量严重下降。以光纤模式的弯曲损耗特性为基础,研究了光纤弯曲半径对高功率全光纤放大器高阶模激发阈值特性的影响。搭建了掺镱全光纤窄线宽高功率主振荡放大系统,设计了不同弯曲半径的水冷光纤盘,进行了相应对比实验。通过优化光纤盘半径,成功抑制了高功率光纤放大器中的高阶模激发,得到了千瓦量级的近单模激光输出,在输出功率为1.31 k W时光束质量因子M2约为1.4。展开更多
文摘Stimulated Raman scattering in a double cladding optical fiber is studied with a continuous wave laser used as a pump source. Under various launch conditions, pump modes are differently excited. Considering the mode coupling effect among the pump modes, the evolution of the power in the Stokes modes is studied. The results show that the scattered waves （the Stokes waves） in the fiber core with 9%tm diameter and 0.14 NA could propagate predominantly in the fundamental mode of the fiber by carefully adjusting the pump light launching conditions.
基金supported by the Natural Science Foundation of Hunan Province,China(No.2018JJ2474)the Huo Yingdong Education Foundation of China
文摘Stimulated Raman scattering(SRS) effect is considered to be one of the main obstacles for power scaling in general-type fiber lasers. Different from previous techniques that aim at suppressing SRS, nonlinear fiber amplifier(NFA), which manipulates and employs the SRS for power scaling in rare-earth-doped fiber, is under intensive research in recent years.In this paper, the authors will present an all-round study on this new kind of high-power fiber amplifier. A theoretical model is proposed based on the rate equation and amplified spontaneous emission(ASE), with random noise taken into account. By numerical solving of the theoretical model, the power scaling potential, heat analysis and advantages in suppressing the undesired backscattering light are quantificationally analyzed for the first time. Then two different types of high-power NFAs are demonstrated individually. Firstly, a laser diode pumped NFA has reached kilowatt output power,and the results agree well with theoretical predictions. Secondly, a tandem-pumped NFA is proposed for the first time and validated experimentally, in which 1.5 kW output power has been achieved. The authors also briefly discuss several new issues relating to the complex nonlinear dynamics that occur in high-power NFAs, which might be interesting topics for future endeavors.
基金supported by Huo Yingdong Education Foundation(No.151062)Hunan Provincial Innovation Construct Project(No.2019RS3017)National Natural Science Foundation of China(Nos.11704409 and 61605246)。
文摘We report a 2 kW all-fiberized Raman fiber amplifier with efficient brightness enhancement based on the graded-index fiber.The maximum power output reaches up to 2.034 kW centered at 1130 nm,with a conversion efficiency of 79.35%with respect to the injected pump power.To the best of our knowledge,this is the highest conversion efficiency obtained for any Raman laser system using graded-index fiber.An optimized fiber combiner adopting graded-index fiber as the pigtail fiber was fabricated,enabling the preservation of the seeding brightness in the core-pumped Raman fiber amplifier,and further enhancing the ultimate brightness of the output laser after amplification.At the maximum power output,the beam quality parameter M2 is 2.8,corresponding to a signal-to-pump brightness enhancement factor of 11.2.As far as we know,we obtain the highest brightness enhancement among Raman fiber lasers of over 100 W,and the best beam quality for graded-index Raman fiber lasers of over 150 W.
基金Supported by the Natural Science Foundation of Guangdong Province under Grant No 04010397.
文摘Employing the technique of symmetry reduction of analytic method, we solve the Ginzburg-Landau equation with varying nonlinear, dispersion, gain coefficients, and gain dispersion which originates from the limiting effect of transition bandwidth in the realistic doped fibres. The parabolic asymptotic self-similar analytical solutions in gain medium of the normal GVD is found for the first time to our best knowledge. The evolution of pulse amplitude, strict linear phase chirp and effective temporal width are given with self-similarity results in longitudinal nonlinearity distribution and longitudinal gain fibre. These analytical solutions are in good agreement with the numerical simulations. Furthermore, we theoretically prove that pulse evolution has the characteristics of parabolic asymptotic self-similarity in doped ions dipole gain fibres.
文摘在基于大模场面积的高功率光纤放大器中,随着放大激光功率的提升而出现的高阶模激发现象,将会导致放大激光的光束质量严重下降。以光纤模式的弯曲损耗特性为基础,研究了光纤弯曲半径对高功率全光纤放大器高阶模激发阈值特性的影响。搭建了掺镱全光纤窄线宽高功率主振荡放大系统,设计了不同弯曲半径的水冷光纤盘,进行了相应对比实验。通过优化光纤盘半径,成功抑制了高功率光纤放大器中的高阶模激发,得到了千瓦量级的近单模激光输出,在输出功率为1.31 k W时光束质量因子M2约为1.4。
