演讲摘要：

Mid-infrared fiber laser sources are beneficial for a broad range of applications, including scientific research, industry, biomedicine, etc. In recent years, 2μm band thulium-doped fiber laser has become more and more maturing, but the fluoride fiber laser with wavelength >2μm is still a hot research topic due to the limitations of key technologies and devices. Our research group has carried out corresponding work in thulium-doped fiber lasers，2.8μm and 3.5μm erbium-doped fluoride fiber lasers and their applications. Thulium-doped fiber laser: 2μm nanosecond and picosecond pulses were achieved by Q-switching and mode-locking technology and as a seed source, the pulses were amplified to over 100 watts by all fiber thulium-doped fiber amplifier. A mid-infrared supercontinuum (1.9 -4.1μm) was obtained with the output power of 10.67W pumped by a picosecond thulium-doped fiber laser and a 3.5μm erbium-doped fluoride fiber laser was achieved pump by a wavelength tunable thulium-doped fiber laser. In addition, we have achieved the transparent polymer welding without any absorber by the thulium-doped fiber laser. Fluoride fiber laser: Based on WSe2 saturable absorber mirror, a 2.8 μm mode-locked Er3+:ZBLAN mid-infrared fiber lasers were realized with an average output power of 360 mW, a repetition rate of 42.43 MHz, and a pulse duration of 21.26 ps. And we pump a segment of Er3+:ZBLAN fiber in a linear cavity oscillator by utilizing a home-made 2μm tunable fiber laser and a 973 nm laser diode. A continuous laser output with a center wavelength of 3456.3nm, a spectral width of 0.2nm, and a maximum output power of 781mW is achieved. Besides, our group has also tackled some key problems of mid-infrared fiber lasers such as the fusion splice technology of the soft glass fiber. We have achieved the fusion splice between ZBLAN fiber and ZBLAN fiber, ZBLAN fiber and silica fiber, passive ZBLAN fiber and chalcogenide fiber. And, in order to solve the influence of the fiber end reflection on the fiber laser system, we have also realized an AlF3 fiber-based end cap for a mid-infrared fiber laser. 中红外激光器在前沿科学研究、生物医疗、工业应用、环境监测、红外成像、光电对抗等诸多领域有着重要应用。近年来，2微米波段掺铥光纤激光器逐渐成熟，但波长>2 微米的氟化物光纤激光器由于关键技术及器件等问题的限制，仍为研究的热点问题。课题组在2掺铥光纤激光器及其应用、2.8μm及3.5μm掺铒氟化物光纤激光器等方面开展了相应的工作，并取得了一定的进展。 掺铥光纤放大器方面：采用调Q及锁模等方式分别实现了多种纳秒、皮秒量级2微米激光脉冲输出，并分别对其进行功率放大，实现了平均功率达百瓦的激光输出；并将其作为泵浦源，实现了1.9-4.1μm，10.67W超连续谱输出及3.5微米氟化物光纤激光输出；此外，采用掺铥光纤激光器也实现了无吸收剂的透明聚合物焊接。 在氟化物光纤激光器方面：采用自行开发的WSe2可饱和吸收镜，结合掺铒氟化物光纤，实现了中心波长2.8 μm、平均输出功率360 mW、脉冲宽度21.26 ps、重频42.43 MHz的锁模脉冲输出；结合自行研制的2 μm可调谐光纤激光器及973 nm半导体激光器，对掺铒氟化物光纤进行双波段泵浦，在线形腔结构下，实现了中心波长为3456.3 nm，功率为781 mW的连续激光输出。 此外，课题组还在软玻璃光纤熔接等中红外光纤激光器核心技术方面进行了一定的研究，实现了氟化物光纤和氟化物光纤、氟化物光纤和石英光纤、无源氟化物光纤和硫化物光纤之间的熔接；也实现了中红外光纤激光器所用的AlF3光纤“端帽”。