3 μm~5 μm中红外激光处于大气窗口波段，对应着众多原子或分子的特征吸收峰，在医疗诊断、大气环境监测、空间通信以及光电对抗等诸多领域具有非常重要的应用价值。在这些应用领域，人们往往要求光源拥有窄谱宽和快速波长调谐功能，而窄谱宽激光具有较小的谱宽、能量集中，是满足这些应用的理想光源。总结了实现窄谱宽3 μm~5 μm中红外激光输出的Fe2+/Cr2+离子掺杂固体激光器和氟化物光纤激光器谱宽压缩技术，以量子级联激光器为例，展示了几种激光稳频的措施，重点阐述了结构紧凑、全固化的中红外光参量振荡器的调谐原理和压缩谱宽所采取的技术，对课题组在窄谱宽光参量振荡器方面的研究工作进行了介绍，并对窄谱宽中红外激光技术的研究前景进行了展望。

3 μm~5 μm is one of the transmission windows of the atmosphere, including many atoms or molecules’ characteristic absorption peaks. 3 μm~5 μm laser souses have wide applications, such as medical diagnosis, environmental monitoring, spectral analysis, military countermeasure, and so on. In these application fields, light sources are often required to have narrow linewidth and wavelength tuning capability. Narrow-linewidth laser is an ideal light source for these applications due to its small spectrum range and concentrative energy. The technology of narrow-linewidth of 3 μm~5 μm laser were summarized, including the linewidth compression method of the Fe2+/Cr2+ ion-doped solid-state laser and fluoride fiber laser, and several methods of quantum cascade laser frequency stabilization were discussed. The compact and all-solid-state mid-infrared optical parametric oscillator was mainly introduced. And the related research work of our group on the narrow linewidth of an optical parametric oscillator was introduced. Finally, the research prospect of the narrow-linewidth mid-infrared laser has been prospected.