Polarized 10-ns frequency-doubled Nd:YAG laser-induced damage to titanium-doped sapphire

In the present paper, the experimental results of a 10 ns, 532 nm Q-switched Nd:YAG laser- induced surface and bulk damage of uncoated, polished Ti:sapphire (Ti:3+:Al2O3) single crystal, grown by the Induction Thermal Field Up-shift Method in our laboratory, are reported. It is found that the measured thresholds of both surface damage and bulk breakdown strongly varied not only with the Ti3+ ion doping concentrations of the tested sample but also with the crystallographic direction of the crystal, whose exact nature has not been previously identified. It is also observed that in the same conditions the surface damage threshold is much lower than the bulk damage threshold. The surface damage is the main cause to laser-induced damage of Ti:sapphire single crystal. In addition, the relative damage morphology and the possible explanation for these experimental results are given.