Investigation of Bulk Laser Damage in Borate Crystals for High-Power all Solid-State UV Lasers

摘要

High-power solid-state UV lasers are in high demand because of the convenient operation procedure. An effective technique for UV generation is cascaded sum-frequency generation pumped by the output of near-IR solid state lasers. The major challenge to such a UV laser seems to depend on the ability and reliability of the nonlinear optical (NLO) crystals that employed for frequency up conversion. The recent development of borate materials such as CsLiB_6O_(10)(CLBO) and □-BaB_2O_4(BBO) have permitted an improved UV generation. In this work, we have investigated the bulk laser damage and the light scatter from bulk defects in CLBO and BBO crystals. Measurement of the laser damage threshold was performed by using a 266 nm laser operating with single shot mode that has a pulse width of 0.75 ns. For the CLBO crystals, the highest damage threshold obtained was 25.4 GW/cm~2, and the mean value of the damage threshold ranged from about 15 to 20 GW/cm~2. These values were higher than that of fused silica 10.4 GW/cm~2. In addition, light scatter from bulk defects was evaluated by using a technique of light scattering tomography (LST). The comparison with BBO crystal and LST results will be presented.