Influence of surface roughness on laser-induced damage of Nd:YAG transparent ceramics

Highly transparent 2 at.% Nd:YAG ceramics were prepared by a solid-state reaction sintering method using commercial high-purity powders of α-Al2O3, Y2O3 and Nd2O3. For the Nd:YAG ceramics sintered at 1750 °C for 50 h, a dense and pore-free microstructure with average grain size of about 15 μm was obtained, whose in-line transmittances reached 84.2% at 1064 nm and 81.7% at 400 nm, respectively. As the surface conditions of Nd:YAG ceramic influence the laser behavior significantly, especially the laser-induced damage, the interaction between laser and Nd:YAG ceramics was mainly investigated. Three kinds of Nd:YAG ceramics with different surface roughness were prepared by different polishing processes. It was found that the surface roughness influenced the laser-induced damage threshold significantly. In addition, we also calculated the laser-induced damage threshold and observed the damage morphology of ceramics.