近年来，携带轨道角动量的涡旋光束在激光加工、光学微粒操纵、超分辨成像、大容量光通信等领域应用广泛，目前已在稀土掺杂光纤激光器中得到了广泛研究。基于声致光纤光栅，实验搭建了全光纤结构拉曼光纤激光器，实现LP₀₁模与LP₁₁模的有效调控，并进一步通过偏振控制实现环形径向偏振光和拓扑荷数l=±1的涡旋光束输出，最高输出功率~70 W，中心波长为1134 nm。文中提出的激光器有利于拓宽涡旋光束输出波段，在多维光通信、光场和物质相互作用等领域具备较大研究价值和应用潜力。

量子亏损对高功率光纤激光器内的废热产生和光光转换效率具有重要影响，光纤激光器输出功率的提升过程可以视为不断与量子亏损作斗争的过程。文中梳理了近年来1 μm波段低量子亏损光纤激光的重要进展，重点介绍了稀土掺杂增益和拉曼增益两种体制的光纤激光器在实现低量子亏损输出方面的相关工作。在稀土掺杂光纤激光器中，采用级联泵浦、多组分掺杂、强泵浦等技术可降低激光器的量子亏损，其中量子亏损≤1%的掺镱光纤激光器已实现400 mW功率输出。在拉曼光纤激光器中，通过采用特殊掺杂、泵浦光谱调控、增益竞争抑制等技术，量子亏损≤1%的拉曼光纤激光器已实现百瓦级功率输出，并成功验证包层泵浦方案的可行性，表明其在实现高功率低量子亏损输出方面具有重要潜力。

An all-fiberized random distributed feedback Raman fiber laser (RRFL) with LP11 mode output at 1134 nm has been demonstrated experimentally, where an intracavity acoustically induced fiber grating is employed for modal switching. The maximum output power of LP11 mode is 93.8 W with the modal purity of 82%, calculated by numerical mode decomposition technology based on stochastic parallel-gradient descent algorithm. To our best knowledge, this is the highest output power with high purity of LP11 mode generated from the RRFL. This work may pave a path towards advanced fiber lasers with special temporal and spatial characteristics for applications.

In this work, an all-fiberized and narrow-linewidth fiber amplifier with record output power and near-diffraction-limited beam quality is presented. Up to 6.12 kW fiber laser with the conversion efficiency of approximately 78.8% is achieved through the fiber amplifier based on a conventional step-index active fiber. At the maximum output power, the 3 dB spectral linewidth is approximately 0.86 nm and the beam quality factor is M_x² = 1.43, M_y² = 1.36. We have also measured and compared the output properties of the fiber amplifier employing different pumping schemes. Notably, the practical power limit of the fiber amplifier could be estimated through the maximum output powers of the fiber amplifier employing unidirectional pumping schemes. Overall, this work could provide a good reference for the optimal design and potential exploration of high-power narrow-linewidth fiber laser systems.