Research Advances in Side-Pumped Solid-State Lasers in the 2 µm Region

Lasers operating in the 2 µm spectral region have significant application value and development potential in fields such as lidar, medical surgery, and mid-infrared nonlinear optics because they are located in the atmospheric absorption window and coincide with a strong absorption peak of water molecules. This article first briefly introduces the energy level characteristics and commonly used crystal matrices of Tm³⁺, Ho³⁺ and Tm³⁺/Ho³⁺ codoped systems, and then reviews the research progress of 2 µm side-pumped solid-state lasers based on these ions and matrices. This review summarizes the research progress of 2 µm side-pumped solid-state lasers, categorized by operating mode and gain medium. Particular attention is given to the mature advantages of Tm-doped garnet lasers in high average power output and the potential of Tm/Ho-codoped fluoride lasers in high-energy, high-beam-quality pulse output. Finally, this paper further reviews the development of side-pumped laser structures and offers a prospective outlook on the future development of 2 µm region side-pumped lasers.