Growth of a Gradient-Doped Single-Crystal Rod with Designable Distribution of Doped Ions by a Laser-Heated Pedestal Growth Method

The thermal effect of a diode pumped solid-state laser mainly caused by nonuniform thermal distribution is the significant bottleneck limiting the output power achievable. In this work, a novel strategy to synthesize YAG crystal thin rods with a designable axial dopant gradient based on the laser-heated pedestal growth (LHPG) method was developed. To make the pump light uniformly absorbed through the whole rod, the optimal doping concentration profile along the axis of single-crystal rods (SCRs) was theoretically deduced. Finite element simulation results demonstrated that the Nd:YAG crystal thin rods with a designed dopant gradient can significantly reduce heat loads under laser operation. Using the grown gradient doped SCRs as a gain medium, the laser diode pumped continuous-wave laser at similar to 1.06 mu m was achieved with the highest slope efficiency of 44% and a maximum output power of 6.46 W. Under the same conditions, the slope efficiency of the uniformly doped SCRs was 38.7% and the maximum output power was 4.95 W. The results show that the SCRs with gradient dopants possess better thermal management and superior laser performance. Significantly, this method also provides a new idea for realizing the controllable distribution of doped ions in crystal growth.