Growth, thermal, and spectroscopic properties of a 2.911 μm Yb,Ho:GdYTaO4 laser crystal
Abstract
A promising 2.911 μm Yb,Ho:GdYTaO4 laser crystal was grown successfully by the Czochralski method for the first time. The crystal belongs to the monoclinic space group of I2/a (no. 15) and high crystalline quality is demonstrated by X-ray rocking curves. The effective segregation coefficient keff of Yb, Ho, and Y are 1.08, 0.96, and 0.9, respectively, all close to 1. Crystal density is measured to be 8.59 g cm−3 by the buoyancy method. Thermal property indicates that the Yb,Ho,Y:GdTaO4 crystal should be pumped along the c-axis in order to reduce the thermal lensing effect. Strong absorption in the range of 900–1000 nm and emission at 2911 nm are obtained in the as-grown crystal. In comparison with corresponding level lifetimes of Yb,Ho:YSGG, Tm,Ho:LuAG, Tm,Ho:YAG, and Ho:YAG, the Yb,Ho,Y:GdTaO4 crystal exhibits a relatively shorter lifetime of 7.298 ms for lower laser level 5I7 and longer lifetime of 419 μs for upper laser level 5I6, which are beneficial to realize population inversion and laser output.