Pulsed optical damage threshold of potassium niobate

We have determined the optical damage threshold of orthorhombic potassium niobate under pulsed laser irradiation for wavelengths of 1054 and 527 nm and pulse durations of 700 and 500 ps, respectively. Six uncoated crystals and two crystals with antireflection coating were tested. The single-shot damage thresholds varied between 4.1 J/cm(2) at 527 nm (lowest value observed) and 26.4 J/cm(2) at 1054 nm (the highest value observed). The threshold fluence was found to depend on the polarization direction of the incident radiation with respect to the crystal axes.