Fabrication and laser performance of planar waveguide LuAG/Yb:LuAG/LuAG ceramics

Planar waveguide LuAG/10 at.%Yb:LuAG/LuAG laser ceramics were fabricated by the tape casting method combined with the vacuum pre-sintering and hot isostatic pressing (HIP) post-treatment. The morphologies of the raw materials, tapes and green bodies were observed. The microstructure, optical transmittance and the Yb³⁺ ions distribution of the LuAG/10 at.%Yb:LuAG/LuAG ceramics with different pre-sintering temperatures after HIP post-treatment were mainly studied. The experimental results showed that the average grain size and in-line transmittance of the HIPed ceramics increased with the increase of pre-sintering temperature. For the LuAG/10 at.%Yb:LuAG/LuAG ceramics pre-sintered at 1825 °C for 20 h and then HIPed at 1700 °C for 3 h under 200 MPa Ar atmosphere, the in-line transmittance of the sample with the thickness of 2 mm was about 74% at 1100 nm and the maximum diffusion distance of Yb³⁺ was about 166 μm. The bulk and grain boundary diffusion coefficients of Yb³⁺ ions for the samples pre-sintered at 1775 °C–1825 °C after HIP post-treatment were calculated by Fick's second law by using the LA-ICP-MS. What's more, CW laser at 1030 nm was demonstrated and the maximum output power of 0.4 W with a slop efficiency of 9.4% was achieved.