Abstract: The gradient-doped Nd: YAG laser crystals were successfully grown in this work, and the concentration distribution of Nd3+ along the crystal growth direction was measured. The temperature distribution of the gradient-doped Nd:YAG crystals and uniformly doped Nd:YAG crystals at steady state under end-pumped condition were simulated through numerical calculations, and it was shown that gradient-doping is an effective method to alleviate the thermal effect of crystals. The laser properties of the Φ3 mm × 40 mm round rod and 1 mm × 10 mm × 12 mm slab structure were further studied. It was found that the maximum output power of the Φ3 mm × 40 mm rod is 7.04 W when the transmission rate of output mirror is 7.5% and the pumping power is 16.05 W, corresponding to an optical-to-optical efficiency of 45.5% and a slope efficiency of 48.4%. While for the slab laser, when the ttransmission rate of the output mirror for 946 nm and 1064 nm laser is 4.5% and 7.5% respectively, the maximum output power is 2.65 W and 4.06 W respectively, and the optical-to-optical efficiency is 25.46% and 41.16% respectively. In addition, the experimental results of different pumping directions also show that pumping gradient-doped crystals from low concentration direction can improve pumping uniformity and enhance laser performance.

Key words: laser techniques, laser crystal, gradient-doping, thermal effect, laser performance