1.06kW 13GHz线宽全光纤激光器

分析了高功率光纤激光器中受激布里渊散射(SBS)效应的抑制方法。研究表明,利用宽带噪声源高速相位调制展宽光谱的方法对于抑制SBS十分有效,可实现kW级用于光谱组束的数10GHz高功率光纤激光子束。通过理论计算线宽与SBS阈值的关系,并分析噪声相位调制各参数对SBS阈值提升的影响,优化了光纤激光器设计参数。通过宽带噪声高速相位调制的方法,展宽单频种子源线宽至13GHz,通过两级预放大至10 W后,使用20/400μm掺Yb光纤最终实现了中心波长1064nm、线宽13GHz、最高功率1.06kW的激光输出,光束质量M21.2,光-光转换效率86%,实验过程未观测到模式不稳定性现象。进一步扩宽噪声源频带,加大调制深度,有望实现更高功率的窄线宽光纤激光输出。

1.06 kW 13 GHz linewidth all fiber laser

The suppression methods of stimulated Brillouin scattering (SBS) in high power fiber laser are analyzed. The results indicate broadening the spectrum with high speed phase modulation is one of the most effective ways to suppress SBS. With a broadband noise generator, kW level several 10 GHz linewidth fiber lasers, which are suitable for spectral beam combining, can be easily developed. On purpose of optimizing the parameters of the fiber laser, we calculate the relationship between the laser linewidth and the SBS threshold. At the same time, the effect of noise modulation parameters on spectral broadening is analyzed by numerical calculation. By broadband noise high speed phase modulation, the linewidth of the seed is broadened to 13 GHz. With a two-stage amplifying, the power is enhanced to 10 W. A 20/400 m commercial Yb-doped fiber is used in the final stage amplifier, which convinces central wavelength 1064 nm, linewidth 13 GHz, maximum power 1.06 kW fiber laser. The M2 is better than 1.2 and the O-O efficiency is 86%. During the whole experimental process, the mode instability is not observed. By broadening the bandwidth of the noise generator or enhancing the modulation depth, a higher power narrow linewidth fiber laser can be expected.