高功率中红外光纤激光光源在前沿科学研究、空间光通信、医学诊断与治疗、环境污染监测和光电对抗等领域有着重要应用。拉曼光纤激光光源输出波长灵活，原则上可以在光纤材料透过窗口范围内获得任意波长激光，是实现中红外激光输出的一种重要手段。目前，基于硫系玻璃光纤、氟化物玻璃光纤、碲酸盐玻璃光纤等中红外玻璃光纤材料，已实现工作波长位于3.77 μm的拉曼光纤激光器、平均输出功率为3.7 W的2231 nm拉曼光纤激光器和波长调谐范围覆盖2~4.3 μm的拉曼孤子激光光源。近期，笔者研究组制备出一种具有高热学和化学稳定性、高激光损伤阈值、大拉曼频移和高拉曼增益系数的氟碲酸盐玻璃光纤，并利用其作为非线性介质，先后实现了级联拉曼散射、级联拉曼光纤放大器、波长调谐范围覆盖1.96~2.82 μm的拉曼孤子激光以及波长为~4 μm的红移色散波，验证了氟碲酸盐玻璃光纤在中红外拉曼光纤激光光源研制方面的应用潜力。主要介绍了氟化物、硫化物及碲酸盐玻璃光纤材料的特点及相应的拉曼激光光源的相关研究进展，并对其未来发展趋势进行了展望。

We report an efficient mid-infrared extracavity optical parametric oscillator (OPO) based on the nonlinear crystal BaGa₄Se₇ pumped by a diode-side-pumped Q-switched Nd:Y₃Al₅O₁₂ (Nd:YAG) laser. The maximum pulse energy of 1.03 mJ at 4.25 μm is obtained with the repetition rate of 10 Hz and pulse width of 12.6 ns when the pump energy was 13.5 mJ, corresponding to an optical-to-optical conversion efficiency of 7.6% from 1.064 μm to 4.25 μm. The idler wave slope conversion efficiency was 12%. To the best of our knowledge, it is the highest reported conversion efficiency for the compact BaGa₄Se₇ OPO driven by the Nd:YAG laser.

We report here on a diode-pumped pulsed mid-infrared laser source based on gas-filled hollow-core fibers (HCFs) towards an all-fiber structure by the tapering method. The pump laser is coupled into an acetylene-filled HCF through a tapered single-mode fiber. By precisely tuning the wavelength of the diode to match different absorption lines of acetylene near 1.5 μm, mid-infrared emission around 3.1–3.2 μm is generated. With 2 m HCFs and 3 mbar acetylene gas, a maximum average power of 130 mW is obtained with a laser slope efficiency of ～24%. This work provides a potential scheme for all-fiber mid-infrared fiber gas lasers.

A dual-wavelength synchronously mode-locked homogeneously broadened bulk laser operating at 1985.6 and 1989 nm is presented for the first time, to the best of our knowledge, which delivers a maximum output power of 166 mW and a repetition rate of 85 MHz. The pulse duration was measured to be 16.8 ps by assuming a sech2 pulse shape. The recorded autocorrelation trace showed frequency beating signals with an interval of 3.8 ps and a full width at half-maximum duration of 2 ps, corresponding to an ultrahigh beating frequency of about 0.26 THz, which agrees well with the frequency difference of the emitted two spectral peaks. The results indicated that such a kind of dual-wavelength mode-locked Tm:YAlO₃ laser could be potentially used for generating terahertz radiations.

We demonstrate a Fe:ZnSe laser gain-switched by a ZnGeP₂ optical parametric oscillator (OPO) under the pulse repetition frequency of 1 kHz at room temperature. The 2.9 μm signal light of the OPO is employed as the pump for the Fe:ZnSe laser. The maximum output power of the Fe:ZnSe laser is 58 mW with the pulse duration of 2.7 ns under the incident pump power of 280 mW, corresponding to a peak pulse power of 21.5 kW and an optical-to-optical efficiency of 20.7%. The spectrum of the Fe:ZnSe laser has a range of 4030.2–4593.6 nm with a dip at 4187.1–4340.4 nm due to the absorption of CO₂.

Gold nanorods (GNRs) with two different aspect ratios were successfully utilized as saturable absorbers (SAs) in a passively Q-switched neodymium-doped lutetium lithium fluoride (Nd:LLF) laser emitting at 1.34 μm. Based on the GNRs with an aspect ratio of five, a maximum output power of 1.432 W was achieved, and the narrowest pulse width was 328 ns with a repetition rate of 200 kHz. But, in the case of the GNRs with the aspect ratio of eight, a maximum output power of 1.247 W was achieved, and the narrowest pulse width was 271 ns with a repetition rate of 218 kHz. Our experimental results reveal that the aspect ratios of GNRs have different saturable absorption effects at a specific wavelength. In other words, for passively Q-switched lasers at a given wavelength, we are able to select the most suitable GNRs as an SA by changing their aspect ratio.

Two-dimensional (2D) materials have attracted intense attention in photonics and optoelectronics for their excellent nonlinear characteristics and are applied for the generation of laser pulses. Here, an active–passive Nd:GdVO41.3 μm laser is realized by using an acousto-optic modulator and gold nanobipyramids absorber. The pulse width of 150.5 ns is obtained in the doubly Q-switched laser. The compression ratio and enhancement time are 82.6% and 16. The doubly Q-switched technology compresses the pulse width, improves the peak power, and stabilizes the pulse, illustrating that double modulation technology opens the door of controllable ultrafast lasers based on 2D materials.