3～5 μm 中红外激光处于大气的窗口波段，在光谱学、遥感、医疗、环保及**等诸多领域都有重要的应用价值和前景。因此对该波段激光器的研究是目前国际上的热门课题。简要介绍了3 种产生中红外激光的方法，分别为：基于非线性理论技术、量子级联技术以及晶体掺杂离子技术，并分别指出了它们的发展趋势。

3-5 μm mid-infrared wave band is in the atmosphere window, which has lots of promising applications on the spectroscopy, remote sensing, medical treatment, environmental protection and military affairs. So, it has been a hot topic around the world to research the lasers at this wave band. In this paper, we describe three ways to get the mid-infrared lasers: technology based on nonlinear theory, quantum cascade technology and doping ions in crystal technology. At last, we point out the trends of their developments respectively.