Recent progress in mid-infrared laser technology

3 ～ 5 μm mid-infrared laser sources have significant applications in many fields and have been intensively studied by researchers.Main technical methods to generate mid-infrared laser radiation are reviewed in this paper,which are as follows: second harmonic generation of CO2 laser,first-overtone CO laser,optical parametric oscillator,DF laser,Fe2 +∶ ZnSe solid laser.The key techniques and problems of each method are concluded and analyzed.The technology tendencies of mid-infrared laser sources are summarized.