报道了一种基于玻璃分相技术制备大尺寸(直径为3 mm,长度为270 mm)掺镱(Yb ³⁺)石英玻璃芯棒,进而制备大芯径(纤芯直径为80 μm,外包层直径为400 μm)掺Yb ³⁺双包层光纤的新技术。实验测试了光纤的折射率剖面、Yb ³⁺吸收谱以及背景损耗,并演示了其激光性能。结果表明:该光纤的纤芯折射率分布均匀,数值孔径约为0.065;Yb ³⁺的掺杂浓度(质量分数)为1.22%,在976 nm处的吸收系数为6.5 dB/m,在793 nm处的背景损耗为0.03 dB/m;基于主控振荡器的功率放大器结构,光纤在976 nm半导体激光器抽运下实现了1080 nm激光输出,光纤长度为2.5 m,斜率效率达到78%,最大激光输出功率为300 W。玻璃分相技术为制备大尺寸、高均匀性有源石英玻璃芯棒提供了新的技术路径,在制备大芯径高掺杂光纤及具有复杂纤芯结构的有源光纤方面具有巨大潜力。

A novel technique, for the fabrication of large size Yb 3+ doped silica glass rod with a diameter of 3 mm and a length of 270 mm and thus a large-core double-clad fiber with a diameter of 80 μm and an outer cladding layer diameter of 400 μm by the glass phase-separation technology, is reported. The refractive index profile, Yb 3+ absorption spectrum and background loss are experimentally tested, and the laser performances are also demonstrated. The results show that the refractive index distributes uniformly within the active fiber core of this fiber and the the numerical aperture is about 0.065. The doping concentration of Yb 3+ (mass fraction) is 1.22%, the absorption coefficient at 976 nm is 6.5 dB/m, and the background loss at 793 nm is 0.03 dB/m. Based on the power amplifier structure of the master oscillator, the lasing output at 1080 nm is realized for this fiber when pumped by a diode laser at 976 nm, where the fiber length is 2.5 m, the slope efficiency is 78%, and the maximum laser output power is 300 W. The glass phase-separation technique provides a novel technique route to fabricate the active silica glass core rods with large size and high uniformity, which has a high potential in the fabrication of heavily doped extra-large-core fibers and active fibers with a complex core structure.