Study on the improvement of ultraviolet damage characteristics of DKDP crystal by dual-wavelength laser conditioning

In order to study the influence of dual-wavelength laser conditioning on the ultraviolet damage characteristics of DKDP crystals, 3 ω (355nm) and 1 ω (1064nm) lasers with different energy ratios were used in DKDP crystals laser conditioning simultaneously. In the case of single-wavelength laser conditioning, 3 ω lasers scan DKDP in raster scanning with increasing energy density lower than crystal damage threshold. In the case of dual-wavelength laser conditioning, the DKDP is irradiated by 3 ω and 1 ω at the same time with different fluence ratios. In the same DKDP region, 1 ω fluence is a constant and 3 ω fluence is varied. The damage characteristics of the samples under 3 ω irradiation (evaluated by damage probability curve and damage density) are obtained by 1-on-1 irradiation. The experimental results show that: (1) Compared with the 3 ω conditioning, the dual-wavelength laser conditioning can improve the damage resistance of DKDP crystals with ultraviolet damage significantly; (2) The best laser conditioning performance is obtained with the fluence of 1 ω equaling 8.8 J/cm² in this paper, here the maximum 3 ω zero probability damage threshold of DKDP crystal is 29.6 J/cm². (3) Under the simultaneous conditioning of dual-wavelength lasers, 1 ω , which fluence is far below the self-damage threshold, participates in the conditioning process, indicating that there is an energy coupling effect between wavelengths.