采用棒管法制备了低羟基含量的Tm3+/Ho3+共掺氟碲酸盐微结构光纤。当使用波长为1 560 nm的激光器泵浦 Tm3+/Ho3+共掺光纤时, 处于Tm3+基态3H6的电子被激发至3F4能级, 进一步通过Tm3+和Ho3+间的能量传递过程3F4→3H6(Tm3+): 5I8→5I7(Ho3+)(能量失配为745 cm-1)布居Ho3+的5I7能级, 5I7能级上的电子向5I8能级跃迁发射出2.1 μm的光。使用1 560 nm光纤激光器作为泵浦源, 18 cm 长的Tm3+/Ho3+氟碲酸盐微结构光纤作为增益介质, 获得了波长为2 063 nm的激光输出。所得激光的斜率效率为12.9%, 激光阈值为163 mW, 未饱和的最大输出功率为40 mW。研究结果表明, Tm3+/Ho3+共掺氟碲酸盐微结构光纤可用于制作2.1 μm光纤激光器。

Tm3+/Ho3+ co-doped fluorotellurite microstructure fibers with low concentration of —OH were fabricated by using a rod-in-tube method. Pumped by 1 560 nm fiber laser, electron at Tm3+:3H6 jump to Tm3+: 3F4, and then energy transfer from Tm3+ to Ho3+ can occure for the reason of small energy gap (745 cm-1) between Tm3+:3F4 and Ho:5I7, fluorescence at ~2.1 μm can be obtained with the transition from level of Ho3+:5I7 to Ho3+:5I8. By using a 1 560 nm Er3+ doped fiber laser as the pump source, an all-fiber lasing at 2 063 nm is obtained from a 18 cm Tm3+/Ho3+ co-doped fluorotellurite microstructure fiber. The corresponding slope efficiency is about 12.9%, the threshold is 163 mW, and the maximum unsaturated laser output power is 40 mW. The results indicate that the Tm3+/Ho3+ doped fluorotellurite microstructure fiber is a promising gain medium for 2.1 μm fiber laser.