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 I_2/a (no. 15) and high crystalline quality is demonstrated by X-ray rocking curves. The effective segregation coefficient k_eff 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.