3D Printing of gradient-doped Yb:YAG laser ceramics by leveraging active mixing

Gradient-doped laser ceramics by 3D printing method have great potentials for high-power laser applications. However, it is challenging for fabricating such type of gain media since different component slurries, as prepared offline, are inconvenient to be precisely fabricated by traditional methods. To address these issues, a facile approach for additive manufacturing of high-power laser ceramics has been proposed for the gradient structure fabrication. First, a material extrusion-based 3D printing device with a home-made active mixing module has been developed to fabricate gradient-doped Yb: YAG(Y3Al5O12) laser ceramics using only two slurries with different doping concentrations. Following that, the active mixing module has been systematically investigated to obtain different Yb doped concentrations of printing slurries with uniform element distribution. By measuring the switching delay volume between different components, the proper volume adjustment has enabled the Yb concentration distribution of green bodies to be consistent with the
designed profile in the 3D process. Finally, multi-component (0-5-10-5-0 at. % Yb: YAG) green bodies have been printed, and experimental tests have been conducted to evaluate the performances of these gradient-doped laser ceramics. Results have shown that the gradient-doped ceramic has obtained 82.1% in-line transmittance at 1100 nm (4.6 mm thickness, along with the doping concentration gradient) and the average Yb ions diffusion distance across the interface has been fitted in the range of 20 to 30 μm. Finally, a 1030 nm laser output with an output power of 4.5 W with a slope efficiency of 41.3% has been achieved pumped with 940 nm laser diode. This study has provided useful insights into developing various types of gradient rare earth doped laser ceramics for high-power laser applications.