Influence of XeCl laser irradiation on the laser damage threshold of the Nd:YAG crystal

摘要

A thin disc Nd: YAG crystal sample was irradiated with 500 pulses of XeCl laser (λ = 308 nm, τ = 20 ns) at ～ 100 mJ/cm~2 laser fluence and 25 Hz repetition rate. The UV-Vis-NIR and additional absorption spectra of the sample showed that optical transmission of the Nd:YAG crystal increased in ultraviolet and visible regions due to elimination of some oxygen vacancies of the crystal following the irradiation. Increase in laser damage threshold of the Nd:YAG crystal sample subsequent to annihilation of oxygen vacancies was obtained by the laser damage threshold experiment. The laser damage thresholds of the irradiated and un-irradiated crystals were measured using 30ns, 1,064 nm single longitudinal mode, TEMoo pulses of a passively Q-switched Nd: YAG laser. The laser damage threshold of the irradiated crystal (after dividing by 3~(1/2) to scale for pulse duration of 10 ns) was obtained to be 501 ± 50 J/cm~2. It is nearly five times as high as that of un-irradiated Nd:YAG crystal, which was found to be 102 ± 15 J/cm~2.