Influence of absorbing centers on the kinetics of accumulation of laser damage in lithium iodate and niobate crystals

An experimental investigation was made of the optical strength of α-LiIO₃ and LiNbO₃ crystals having different defect concentrations under repeated exposure to laser radiation at wavelengths of 1.06 and 0.53 μm. It was found that an increase in the defect concentration reduced the optical strength of LiNbO₃ crystals over the whole range of laser energy densities W. However, for α-LiIO₃ a tendency toward "strengthening" (increase in the optical strength) was observed, this being more appreciable at λ = 1.06 μm than at λ = 0.53 μm. The results indicate that laser damage under repeated and single exposure is due to absorbing centers.