180 W单频全光纤激光器

高功率单频光纤激器在相干探测、功率光谱合成等方面具有广泛的应用前景。分析了高功率单频光纤激光器中受激布里渊散射效应的抑制方法，研究了放大级特性对受激布里渊散射效应的影响。采用线宽为70 kHz的单频光纤激光器作为种子源，经两级光纤放大，实现了中心波长1 064.1 nm、线宽70 kHz、最高功率为180 W的单频全光纤激光输出，光-光转换效率71.1%，光束质量Mx2=1.2，My2=1.21。分析了改变放大级特性前后输出功率提升的原因，认为改变放大级的温度分布减小了受激布里渊散射效应的增益系数，提高了输出激光的受激布里渊散射阈值，促使改变放大级温度分布后的输出功率大幅提高。该激光器的输出功率仅受限于泵浦功率，进一步提高泵浦功率，有望实现更高功率的单频光纤激光输出。

180 W single frequency all fiber laser

High power single frequency fiber lasers are extensively applied in coherent detection and power spectrum beam combination etc. The suppressing method of stimulated Brillouin scattering was analyzed. The influences of amplification level on stimulated Brillouin scattering were studied. A single frequency fiber laser with linewidth of 70 kHz was used as seed source. And through two stage amplified, the central wavelength of 1 064.1 nm, linewidth of 70 kHz and power of 180 W were achieved respectively. The optical-optical efficiency is 71.1%. And the beam quality is Mx2=1.2 and My2=1.21. The output power before and after changing amplifier characteristic was compared. And the reason that output power increased was analyzed. The stimulated Brillouin scattering gain coefficient was reduced by varying amplifier temperature distribution. Then stimulated Brillouin scattering threshold was promoted. Finally, this makes the output laser power increase greatly after varying amplifier temperature distribution. The output power of this laser is only limited by pump power. If the pump power is increased, the higher power of single frequency all fiber laser will be achieved.