Effect of Strontium Ion on the Growth and Second-HarmonicGeneration Properties of GdCa₄O(BO₃)₃Crystal

Large sized and optical quality GdCa₄O(BO₃)₃(GdCOB) crystal with calcium partially substituted by strontium (Sr) ions was grown for the first time. The x-ray powder diffraction shows that the Sr ion has an effect on the cell parameters of the GdCOB crystal. Second-harmonic generation (SHG) experiments were performed on the Sr:GdCOB and GdCOB crystals along the spatial phase-matching direction. The results show that the cw green laser output power is 1.04W when the laser diode pump power is 10W in the Nd:YVO₄/Sr:GdCOB intracavity laser. Considering the slope efficiency of Nd:YVO₄ and the fundamental laser in cavity, the intracavity SHG conversion efficiency of the GdCOB crystal is 21% while it is 24% for the Sr:GdCOB crystal, the SHG conversion efficiency is improved by 14%. The effect of the Sr ions on the nonlinearity of the GdCOB crystal is also discussed by using the anion group theory.