A brief introduction: Nd: YAG single crystal is the most important laser crystal, widely used in industrial, medical, and scientific fields. The main advantages are: low light output threshold, high gain, high efficiency, and low 1064 nm loss; At the same time, Nd: YAG has high optical quality, good thermal conductivity, resistance to thermal shock, and high mechanical strength, making it the most suitable and commercialized laser crystal for continuous, pulsed, and mode-locked lasers. Nd: YAG crystals are also widely used in various solid-state laser systems, such as frequency doubled continuous waves, high-energy Q-switches, inverted cavities, and so on.