Crystal growth and laser properties of gradual concentration Nd-doped yttrium aluminum garnet serial crystals

The laser crystals of Nd:YAG and Nd:GdYAG with gradual concentration were grown successfully by a Kyropoulos Similar Method. The concentration of boule part of the three grown crystals were 0.17 -0.38 at% Nd: YAG, 0.95 -2.86 at% Nd:YAG, and 0.18 -0.32 at% Nd:GdYAG, respectively. Meanwhile, the absorption co-efficients of boule part of the three crystals increased gradually along the growth direction near 808 nm. Three crystal rods with dimensions of CYRILLIC CAPITAL LETTER EF 3 x 40 mm were processed from boule part of the grown crystals. The laser performance of the three rods under different transmittance output mirrors and different pump directions were characterized. The optimal laser slope efficiency of 0.17 similar to 0.38 at% Nd:YAG and 0.18 -0.32 at% Nd:GdYAG were 52.8% and 55.0%, respectively, when the transmittance of the output mirror was 15%. And the optimal laser slope efficiency of 0.95 similar to 2.86 at% Nd:YAG was 47.4%, under a 30% transmittance output mirror. Moreover, when the high concentration end is the pump incident end, the laser slope efficiency is reduced. The results show that the laser efficiency can be greatly improved, when pumping along the low concentration end. The gradual concentration crystal is helpful to improve the laser performance.