Investigation of bulk laser damage threshold of lithium niobate single crystals by Q-switched pulse laser

Bulk laser damage threshold of 2-in.-diam. MgO-doped LiNbO3 crystals grown using the Czochralski technique has been measured using a Q-switched Nd3+:LiYF4 laser. The threshold showed dependence on the crystal quality. The highest bulk laser damage threshold (14 J/cm2 at 1.053 μm wavelength with 1-ns pulse width) was obtained in the LiNbO3 crystal doped with 1 mol % of MgO. The lowering of bulk laser damage threshold was observed in the crystals doped with MgO at more than 3 mol %. These crystals contained the local aggregations of MgO which increased the scattering centers and decreased the transparency.