Research on 2 μm laser based on a novel step concentration Tm: YAG crystal

This study employs step concentration technology to significantly reduce the severe thermal effects experienced by Tm: YAG crystals under high-power pumping. Firstly, the thermal distribution and thermal stress of Tm: YAG crystals with three different step concentrations are simulated respectively. It has been observed that the thermal conduction and distribution within the crystal vary with the concentration and length of the crystal. In the experiment, the output performance of LD-pumped Tm: YAG lasers with three different step concentrations was compared. In the continuous operation, the measured slope efficiencies were 35.34 %, 38.34 %, and 40.82 %, respectively. In the Q-switching operation, the slope efficiencies were 10.32 %, 10.87 %, and 12.56 % at the repetition frequency of 300 Hz, and the beam quality factor M2 was 1.63,1.52 and 1.46, respectively.