High-power narrow-linewidth rare-earth-doped fiber lasers, which are well known for their high beam quality and high efficiency properties, have rapidly developed in the last decade, due to the needs of a vast range of applications such as nonlinear frequency conversion, and incoherent spectral beam combination to further scale up the total output power of fiber lasers. At the same time, many efforts have also been made to extend the operating wavelength of narrow-linewidth fiber laser toward the longer mid-infrared wavelength region, which was motivated by a large number of promising applications such as atmosphere monitoring, and pump source for mid-infrared optical parametric oscillator. In most cases, thulium-doped fiber lasers operate efficiently in a wavelength range of 1.8–2.1 µm, which could be considered as being one of the most important sources of narrow-linewidth laser radiation that has been developed and intensively investigated in the last several years. Here, we demonstrate a high-power narrow-linewidth continuous-wave thulium-doped all-fiber laser based on master-oscillator power-amplifier (MOPA) configuration. The MOPA yields 342 W of narrow-linewidth laser output at the central wavelength of 2000.3 nm with a 3-dB spectral bandwidth of 90 pm. The beam quality factor is measured to be M 2 of<1.15 at an output power of 300 W. No indication of stimulated Brillouin scattering could be observed at the highest output power level, and the output power is only currently limited by 793 nm available pump power. This kind of high-power narrow-linewidth thulium-doped all-fiber MOPA represents a promising achievement in the generation of high-power laser source via incoherent spectral beam combination.%报道了一个全光纤主振荡功率放大结构的窄线宽连续掺铥光纤激光器,该激光器由窄线宽连续掺铥光纤激光种子源和两级包层抽运掺铥光纤放大器组成.自制的窄线宽掺铥光纤激光种子源经过两级高功率包层抽运掺铥光纤放大器之后,最高平均输出功率为342 W,掺铥光纤功率放大器的斜率效率为56%,输出激光的中心波长为2000.3 nm,3 dB光谱带宽仅为90 pm.在放大过程中,功率放大器的反向监测端没有观察到受激布里渊散射效应,输出功率仅受限于当前可用的793 nm半导体抽运源的功率.据我们所知,该结果为目前国际上2µm波段全光纤结构窄线宽激光器所产生的最高输出功率.
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