2 μm band laser has broad application prospects in many fields due to its unique wavelength absorption characteristics. Water molecules have a strong absorption peak near 1.94um, making 2 μm band laser safe for human eyes and suitable for applications such as remote sensing detection, laser radar, and other fields, which can detect water vapor, wind speed, etc. in the atmospheric environment. At the same time, the penetration depth of 2 μm band laser into human tissue is shallow, making it a precise “scalpel” and having good hemostatic effect. It has been applied in medical fields such as laser lithotripsy, soft tissue cutting, and urinary system treatment. 2 μm band laser is in the high atmospheric transmittance window, with low scattering loss and strong penetration ability for smoke and other substances, suitable for space communication. 2 μm band laser is also an important pump source for 3 ~ 5 μm band mid-infrared optical parametric oscillators, which has important application prospects in mid-infrared active detection, security and optoelectronic countermeasures. Most transparent organic materials have strong absorption in the mid-infrared 2 μm band, and 2 μm laser has high processing efficiency for cutting, welding, marking, etc. of plastics.