Fabrication and kW ‐level MOPA laser output of planar waveguide YAG /Yb: YAG / YAG ceramic slab

Using the tape casting method combined with vacuum sintering and hot isostatic pressing, high‐quality planar waveguide YAG /10 at.%Yb: YAG / YAG ceramics were successfully prepared. For the sample presintered at 1750°C for 30 hours and then HIP ed at 1700°C for 3 hours in 200 MP a argon, the in‐line transmittance reached 82.5% at 400 nm and the average grain size was ~17.1 μm. The diffusion behaviors of Yb ions across the contact boundary between the cladding YAG layer and the core Yb: YAG layer were determined by Fick's second law. Then, a 1030 nm continuous‐wave ( CW ) Yb: YAG planar waveguide ceramic laser based on the structure of master oscillator power amplification ( MOPA ) was realized. After a single‐pass amplification, the maximum output of the ceramic slab (60 × 10 × 1 mm 3 ) reached 1251 W and the corresponding optical‐to‐optical efficiency was 30.0%, which is the highest output power of a Yb: YAG planar waveguide ceramic laser to the best of our knowledge.