The self-quenching mechanism of the H4 and F4 levels of Tm:YAG crystals can generate two-photon excitation at the upper level, potentially making it an efficient way for lasers to achieve high quantum efficiency. Tm:YAG crystals are widely used in lidar and other atmospheric detection fields because of their operating wavelength of 2013nm. The fluorescence lifetime of Tm in Tm:YAG crystal is twice as long as that of Tm:YAP crystal, the emission cross-sectional area of Tm:YAG crystal is slightly lower than that of Tm:YAP crystal, and the peak absorption band is 785nm, which is more suitable for semiconductor diode pumping.